Vehicle and Automotive Engineering 4

We can see a rise in the number of smart vehicles in the last past few years. These types of cars are usually or, in other words, they are physically work as intelligent as robots. Intelligent vehicles have become an important part as they are equipped with intelligent agents that give services to human beings. It is approximated that over 1 billion cars travel the streets and roads of the world today. With such traffic, it is apparent that there are many situations where the driver has to react quickly. As Intelligent vehicles are connected to a large amount of data, these data may be dimensionally decreased and kept as latent data. Then, when needed, they can be reconstructed and used. The aim of the current paper is an approach to the implementation of an unsupervised autoencoder technique in intelligent vehicles. The autoencoders have significant importance as they detect and recognize unknown data. In this case, we can say the autoencoders may replace labelled supervised neural networks if they learn effective encoding (data representation).

At the industrial level, great progress has been achieved since the deployment of communication systems. These technologies have succeeded in recent decades, allowing the emergence of growing user needs in terms of accessibility, speed, amount of data and energy consumption. Thanks to communication systems, the intelligence embedded in objects could ensure their connectivity and respond to a need for control or monitoring. The main aim is not only to improve user connectivity but also to connect billions of objects between them. These connected objects are physical elements, autonomous electronic/digital devices, capable of communicating with each other, thus enabling a revolution in technology that brings more ambitious innovations in different areas of application such as medicine, industry, environment or security. Since the appearance of the Industry 4.0 concept, wireless communication became a significant tool to shift to this paradigm, where the machines and robots started to be controlled remotely. Until now, wireless digital data transmissions are based mainly on the modulation of electromagnetic waves (in a very wide range of frequencies and according to various methods). For example, in the industry, we can directly transmit data by radio waves using a radio modem in association with an adequate communication protocol or in association with certain network technology, which adapts to it. Among these different possibilities, we can distinguish the WiFi and ZigBee technologies, all the technologies used by the cellular networks of mobile telephony, and technologies exploited to communicate with the satellites. We can also consider RFID technology (Radio-Frequency IDentification) which is essentially used as a proximity interface for the purpose of identification and traceability. Apart from industrial applications, we can find Bluetooth networks, the radio local loop (BLR), Wimax and WUSB (Wireless USB). This paper presents a case study on the RF communication of remote-control toy vehicles. The paper will be divided into three parts. The first part highlights a literature review of RF communications and their use in the remote control. The second part mainly describes our measurement system and the used vehicles. Finally, we will show the results of our measurements and show the direction to substitute the remote controllers of the vehicles for building a centralized control for multiple vehicles.

It is well known that all the physical devices that surround us, in our daily life are nonlinear systems, the meaning in which the change of the output is not proportional to the change of the input, which results from changes in variables over time, to model such system with the aim to control it, was always an issue for the researchers, where from the literature review, many methods and solutions were created in order to facilitate the task. One of the most efficient approximations was linearizing the system and using linear or nonlinear controllers, so the theoretical part can be more friendly to handle it, the model still is far from reality, therefore it can contain errors and not reliably responds as the real environment. The paper is based on the nonlinear controller system. The controller is embedded with the nonlinear model predictive tool with the aim to track the path executed by the quadrotor. The paper is divided into three sections, the first section highlights a literature review about the efficiency of the linear and nonlinear controllers in the automation and control field, focusing on the nonlinear controllers. In the second section a case study of the nonlinear predictive control application for Tello quadrotor is presented. Finally, the simulation results are discussed, and a comparison is made to understand the potential of using a nonlinear controller instead of a linear one.

Today the automotive industry is making great strides toward driverless driving. Vehicle manufacturers, as well as well-known development service providers, have already developed a large number of concepts and design studies for fully automatic vehicles. In the future, there will be no more limits to driverless driving. However, a fully autonomous vehicle must also protect its occupants in the event of an accident. The driver becomes a passenger, no longer having to take part in driving the vehicle. The big challenge for the future is how the seat that can be rotated in the front row of a car will have an impact on the future passenger safety system. The aim of the research is to build a simulation model that will allow us to study the area. It is absolutely necessary to use a real test to validate the simulations. To investigate the influence of swivel seats on the restraint systems, the seat positions to be analyzed must first be narrowed down. The area examined extends from 0˚, which corresponds to the current driver’s seat position, to the 180˚ position, in which the driver’s view is directed towards the rear. In order to limit the number of variants that are examined, the angle steps are limited. As part of this research, the 0˚, 30˚, 60˚, 90˚, 135˚, 180˚ positions of the seat are examined in more detail and examinations are carried out on the basis of these variants.

This paper deals with the implementation of a system for signaling the approach of vehicles using a distinguished signal within other vehicles. According to the literature processing, the two main warning systems of emergency vehicles, i.e., the light and sound signal, may not be sufficient. Literature processing also covers vehicle communication technologies and important relationships with DMRS technology. The paper also contains an example of an application described for LTE-V technology and details existing transceiver technologies, such as transmission at conventional car radio frequencies. Taking into account cost-effectiveness, the system used in the paper consists of a radio transceiver using a frequency of 433 MHz, Arduino development platforms, and input and output devices. A joystick was installed on the transmitter side to test the operation of the system, while four LEDs were installed on the receiving side to simulate directions. Electronic circuits containing the Arduino platform have been designed and constructed in order to perform the RF communication among the receiver and transmitter.

Our cars make our everyday life much easier. With their help, in a day full of programs, we can get anywhere on time without carrying our packages on our own. In our rushing world, there is the probability that even if we have enough time to get there somewhere, we will hurry, which leads to inattention or worse case an accident. Car manufacturers have a huge amount of research projects to install driver-assistance safety electronics into our cars that, even if they are not driving, instead of the driver, alert to an accident and help to avoid a stutter or a life-threatening accident. According to the Hungarian Central Statistical Office (KSH), research on car manufacturers has brought significant results, as while in 1990 there were nearly 37,000 accidents involving personal injuries on the roads, in 2020 there were only 18,000 such accidents. However, in addition to these active and passive safety features, we need to be aware of and follow the written and unwritten rules of road safety. However, the number of passenger cars has increased so significantly in the last 20–25 years—but especially in the last two years due to the coronavirus epidemic—as roads are characterized by such a high degree of congestion that pedestrians and cyclists require much more attention from participants. This way it is important children receive proper education on the rules of walking or cycling at nursery school and preschool age. The aim of the study is to enumerate and present the platforms that help children to learn, know and deepen the rules of safe traffic.

In the premium vehicle category, real-time online internet connection has become a standard in recent years. This trend is likely to spread completely in the automotive industry in the coming years.This fact offers a lot of new options in the field of vehicle maintenance (and predictive maintenance).Another possible use case may be remote diagnostics of in-use vehicles on the market, analysis of their online data and thereby an extension of the product development process after SOP.An additional new option may be to automatically collect, evaluate and generate of onboard diagnostics data to report to different authorities. E.g. OBFCM (onboard fuel consumption) or IUMPR j3 (in use monitoring performance ratio) field reports.In vehicle production, during the test drive, it could be possible to read and log of measurement data of the finished vehicle’s control units online Another application may be to test vehicles online during the production process e.g. to read of DTC’s (diagnostics trouble codes) during technical tests or to monitor of SoC (state of charge) of battery online while moving vehicles within the factory.

In collaboration with safety, security, infocommunication and transport science, self-driving vehicles are going to transform the future of the transport technology. Due to technological innovations and specificities, new risks and vulnerabilities are emerging in terms of modern road vehicles and more increasingly in terms of autonomous vehicles. These vulnerabilities should be addressed at the design stage already. Autonomous vehicles just as manufacturers of intelligent and networked cyber-physical systems, are supposed to meet the interoperability requirements and consider security threats and safety hazards at the same time.The autonomy level of the vehicles is increasing therefore, they are becoming more and more similar to a rolling computer, evaluating and using more and more information, retrieving information from their environment with their sensors and from each other or gathering it from track elements. Based on this incoming data intelligent vehicle systems are able to identify potential hazards.Irrespective of the communication channel, protocol or information gathering solution, the vehicles must be protected from external threats also by allowing access only to authorized users, ensuring the possibility that the traffic information can be processed, retrieved, and examined retroactively in addition to the security risks of information, communication.The research in this study summarizes the safety solutions from the past and present and the solutions expected in the short and long term.

The relationships used to calculate the contact ratio of Gleason spiral bevel gears are not published or the formulas found are of an empirical nature, and the theoretical background of which is unknown. Since the spiral bevel gears have a localized contact pattern, the actual contact ratio depends on the shape and size of the contact pattern. In the known formulae, no reference was made to this consideration. To solve the uncertainty, we have developed a method that gives a general interpretation of the contact ratio. It is based on the operation of the gear pair and is suitable for taking into account the localized contact pattern.

A delayed dynamic model of vehicle lateral motion system is established to investigate the vehicle dynamics under time delay and to optimize the effect of time delay. The dynamic model is based on the non-linear 2-dimensional vehicle equation of motions and includes an active PD torque controller with feedback time delay. The wheel rotational dynamics and the longitudinal-lateral tyre force coupling are also modelled regarding the deformation delay induced by tyre elasticity. Phase plane analysis is carried out to acquire the handling and stability properties of the uncontrolled vehicle, and on this basis, the stability analysis of the delayed system is conducted and summarized in the stability chart of two control parameters, which shows the effects of time delay on vehicle system in various driving conditions and handling characteristics. Finally, simulations validate that the stability analysis for the controlled system dynamics and the eigenvalue-based optimization method performs effectively, which can be used for many considerations in vehicle delayed systems both from theoretical and practical viewpoints.

With the recent advancements of the fourth industrial revolution, many sensors are implemented into the products that collect the data and monitor their performance. The measurement data can be stored with the numerical models as a digital twin, and these can serve as a virtual replica of a physical object or process. These digital twins can improve the design and optimization process. The paper uses an open-source tool, the Digital-Twin-Distiller, which can encapsulate the realized finite element analysis of a model into a web application, which can be integrated easily into an optimization chain or any other business process. The paper proposes a numerical model and cogging torque analysis of an interior permanent magnet synchronous machine. The paper examines the effect of two parameters of the magnet groove shape on the cogging torque of the Prius 2004 motor model. It was found that the cogging torque of the motor is highly dependent on the shape of the flux barrier, even with minor changes. On the other hand, the wedge between the two magnets does not affect cogging torque much.

The application of metal foam in the vehicle industry is not a novelty. Owing to the strict emission and consumption requirements, the use of composites and metal foams can be useful for reducing the mass for car manufacturers. Along with sustainability, higher safety features are also expected by the users in the case of new vehicles. This requirement also confirms the necessity of the metal foam application in the vehicle structure since the porous feature results in high absorbed energy by the low mass. The present study is a prework of subsequent development of a special crumple Crushbox part of the vehicle front, which is working on the principle of radial constrained foam compression. In this study discussed compression experiments confirm the fact, that the energy absorbed capacity of a metal foam can be improved in different radial constrained applications. The significant absorbed energy difference can be expected due to the increase in the densification region.

The focus of this paper is on the analysis of the degree of freedom and mobility of a tilting table with parallel kinematics using the mechanism module of parametric software. Parallel kinematics is also used in many places in the automotive industry, for certain workpieces where the orientation movements change only in a narrow range (e.g., draft angles of casting tools), then the workspace constraints of the unit with a parallel kinematic chain can be disregarded, and placement of body parts in the automotive industry. The paper presents an analytical calculation of the degree of freedom and mobility of a tilting table with parallel kinematics using the modified Chebyshev – Grübler – Kutzbach formula. The result of the analytical calculation will be verified with parametric software. This is significant because the Chebyshev – Grübler – Kutzbach formula ignores the geometrical characteristics of the structure during analysis. The model of the investigated structure consists of solid parts created with parametric software. The mechanism modul of the parametric software provides an opportunity to analyse the kinematic properties of the investigated structure. The purpose of the studies on the kinematics of the mechanism is to verify the validity of the analytical calculations.

The fuel consumption of autobuses is significantly influenced by the different losses, such as air resistance, tyre rolling resistance of tire and other losses (bearing losses, losses in the drive, gearbox, etc.). The main goal of my current research is to work out indirect methods of measurement via experiments carried out with Mercedes-Benz REFORM 501 autobus to define rolling resistance, one of the most decisive losses. During the evaluating of measurements, I used a special method because the power values were determined based on the power characteristic curve of OM 936/260 kW engine of the bus. During my calculations, I considered the losses due to rolling resistance and air resistance and other losses due to the use of additional auxiliaries furthermore, the losses in the drive elements of the vehicle (3% of the used engine power) were considered as constant. Later on, the defined values will serve as input data for modelling the vehicle energetics calculations.

The paper aims to study the constructive solutions for an adder and distribution box used in the transmission of a heavy truck used in oil drilling. The main problem that needs to be studied is to reduce the vibrations of this structure and the study of an optimal solution, from the point of view of operation but also of the production price. The adder and distribution box is a complex part of the trucks and is very noisy. Experimental tests come to validate the model used for the mechanical study of the structure. The symmetry of the structure also allows the simplification of the model used. The design, taking into account the concrete conditions of the rocks (accidentally and randomly appeared at the level of technological equipment) in which it is drilled, would lead to technical solutions - obviously unsatisfactory - for the production of sum box constructions adapted to various local conditions drilling, eliminating or greatly reducing the particularly important economic aspects of engineering construction. The new solution found and proposed to the designers is presented in the paper.

External helical gears play an important role in the development of drive chains. Powertrain gears are expected to show a minimum level of vibration and noise level. The most significant source of vibration excitation and noise is the contact zone. Effects of errors caused by the manufacture, assembly and load are also displayed in the zone of contact. In this article, we will focus our investigation only on error-free gears (free from manufacturing, assembly and deformation errors). The continuous change in the contact zone is the change in the length of the contacting generating lines of the meshing. The contact zone can change its shape from a regular rectangle to a completely general one as a result of modifying the top land surface. We will examine the effect of the parameters and the shape of the contact zone on the total length of the contacting generating lines. In this article, the first step is to study the regular rectangular contact zone of external-external gear pairs.

Diagnostic strategies play a vital role in achieving high competitiveness, better productivity and improving workplace safety because the technical diagnoses provide solutions for all issues related to the following tasks: determination of the actual technical conditions; detection of the defects; isolation and identification of the component that failed; make the appropriate decision in order to maintain high reliability of machines without having to disassemble any of its parts and explain the malfunction. Furthermore, the prognostic aspect is a very challenging goal in machinery to improve the performance, fixing the error before the malfunction occurs, assessing the condition of the equipment, and whether maintenance is necessary, which will give more specialised recommendations for the operators. The article’s objective is to elaborate the conception of a diagnostic system for marine diesel engines in real-time conditions and find the most proper strategy to develop a diagnostic system that will increase the reliability of machines and reach maximum efficiency. In the first part of the study, the relevant literature is introduced to diagnose machine malfunctions which is vast and varied due to the diversity of systems and components. In the next part of the article, the possibilities of using Artificial Intelligence techniques are described to develop a significantly improved diagnostic system convenient for ship’s operating systems. After that, the determination of diagnostic parameters in diesel engines is described to simplify the complexity and instability of the whole system. In addition, the causes that lead to damages and failures in main engines are introduced. Finally, some perspectives on important challenges and future directions are discussed and highlighted for future research. The main added value of the study is that the conception of the most proper diagnostic and prognostic strategy for the diagnostic system was elaborated, especially for the marine diesel engines, to increase the reliability and efficiency of the engines.

Knowledge-Based Systems apply Artificial Intelligence techniques to solve difficult problems in complex systems that well-trained experts can only manage. These systems can support the decision-making of inexperienced people with the necessary tools to do work that requires high expertise. These systems depend on three main resources: human expertise, experiments, and previous observations. Furthermore, Knowledge-Based Systems reduce the complexity of operation and implementation, making them flexible and easy to understand. The combination of knowledge-based diagnostic methods with recording and monitoring of operating variables; furthermore, adding them to the knowledge base improves the efficiency and reliability of detecting the machine’s behaviour and the effectiveness of the whole system. The aim of the study is to develop a Knowledge-Based System including five stages that could be improved separately to optimize the operation of the machines. In addition, this system allows the evaluation, updating, modification, and integration of the rules in the knowledge base, which results in efficiency improvement of the machines’ operation. Firstly, this paper briefly introduces the different methods to analyze knowledge obtained from human experts in the most effective way. We aimed to maintain the quality of the information and define the effect that experts and the types of machines being understudied on selecting the most suitable method to deal with this information to form the final knowledge base. After it, we reviewed the theories that deal with uncertain and qualitative information and the most appropriate theory for the Knowledge-Based System. Finally, different directions in software tools for Expert Systems development were reviewed. The main added value of the study is the development of the new Knowledge-Based System, which can be handled more flexibly by inexperienced users and increase the reliability and efficiency of the marine diesel engines.

Screw threads and bolt connections have appeared already in ancient times in technical practice. Archimedes was an ancient Greek scientist in the IIIrd century AD. He created the mathematical description of the helix, that is the base of several inventions (e.g., a water-lifting screw). Nowadays, screw connections have become the most commonly used fasteners and become the most common machine element. Their simplicity and the possibility of repeating the assembly almost any number of times led to their widespread use in the mechanical engineering industry. It is not different in vehicle manufacturing either. There are many places in vehicles where the precise adjustment of the clamping force created by the joint is an important parameter, like the bolts that secure the wheels or the various elements of the drive units. It is important to create clamping force, but not cause excessive deformation that would adversely affect either the contact surfaces or the gaskets. The aim of the research presented in this publication is to examine how to construct CAD models and FEM models of a bolted joint in order to obtain relevant information for a bolted joint installed in a given location. The publication describes why it is recommended to pay attention to creating CAD geometry so as to the model can be processed by the FEM software. The research examines the displacements caused by the tightening torque. The two presented simulations can be the basis of the tightening sequence of the bolts in the case of a machine element with many bolt connections.

The heating is always a more important problem for drive units with plastic gears, even in simpler applications than with steel gears. The strength of plastics can change dramatically even at a temperature that occurs in the everyday environment, such as in places exposed to direct sunlight. In gearboxes, this can have a significant effect on the behaviour without rapid failure of the components, while higher temperatures lead to greater deformation of the tooth surface and greater wear and thus, it can reduce the contact ratio. At the same time, plastic gears are often used without lubrication, and in such circumstances, temperature also has a significant effect on the tribological properties of plastics. There are several methods for calculating the heating of plastic gears, which can give conflicting results. Some of these have become obsolete over the years but are still used today, for example, the VDI 2545 or the modified VDI 2545 calculation method. In the past, we have been able to demonstrate that reactive loads, especially in the drive units with small plastic gears performing a supporting function can lead to significant local temperature rises in the contacting teeth. Pulsating or continuous but variable reactive loads can cause heating similar to or greater than in the case of the normal operation. This heating can significantly affect the operating clearance and the strength characteristics of the gears. The temperature rising effects of reactive loads are measured with the help of special drive units, which proved to be a very useful method. In this article, we present some of the most commonly applied computing methods of heating. This is followed by a description of the specific drive units that we use to investigate the heating induced by the reactive loads and the principles of the measurement that can be performed with them.

Tyre forces are the primary external forces applied to a vehicle, especially at lower speeds, but are notoriously difficult to measure or predict. An intelligent tyre that allows the external forces to be determined from simple measurements can be used to improve vehicle safety systems like ABS and stability control and mitigate collisions. An intelligent tyre has been developed at the University of Pretoria using stereovision cameras to measure strain and displacement on the inner surface of a tyre, but a model to predict force from these measurements has not been developed yet. This initial study investigates the viability of predicting external tyre loadings from inner tyre deformations.

This work describes the design and implementation of a low-cost Advance Rider Assistance System (ARAS). Motorcycle riders are more prone to the injury during an accident than passengers of the car. For riders those accidents often end up tragically and additionally, there is a higher chance that rider will be involved in the accident than the passenger of a car. Therefore, there is a need for devices that can increase the passive and active safety of bikers. The work describes the design verification and implementation of a simple and affordable assistance system with traffic sign recognition, pedestrian recognition and proximity alert function. Device contains sensory unit equipped with a camera for pedestrian and traffic sign recognition, infrared (IR) rangefinder for proximity measurement and a combination of Global Position System (GPS) sensor and Inertial Measurement Unit (IMU) for the independent speed measurement of the motorcycle. Displaying unit contains Head-Up Display (HUD) and is placed on the helmet. Methodology part describes considered scenarios which could be prevented and possible solutions. In addition to the mentioned functions, the possibility of future extension with smart infrastructure communication functions like Vehicle-To-Vehicle (V2V) and Vehicle-To-Infrastructure (V2I) is taken into account. Based on these considerations, a suitable mechanical solution and used hardware was selected. Design study describes mechanical and mechatronic design and is supplemented by analyses. Implementation part describes software solution (both of sensory and displaying unit) and prototype manufacturing using 3D printing. Test part describes conducted tests and their results, with special emphasis on proximity alert response rate and capability of vision system using cascade classifier. Several further improvements (features which are currently under development, such as night vision, improved scene recognition, people on wheelchairs recognition, etc.) are described at the end of the article. Conclusion involves further work and new ideas that came up during the process.

Several types of research related to hydraulics are currently underway at our institute [6–9], but this paper aims to investigate the hydraulic drive. The energy transfer at the hydraulic drives can be solved by electrical analogy with direct current hydraulic drives and alternating current hydraulic drives [2–4]. At the direct current hydraulic drives, the operating fluid flow in one way besides the alternating current hydraulic drives, where it alternates periodically between the hydrogenerator and the hydromotor. The alternating current hydraulic drives have two types. The alternating current synchronous drive and the alternating current asynchronous drive. The alternating current hydraulic drives have two main units: the alternating current hydrogenerator and the alternating current hydromotor. The angular position of the hydrogenerator and the hydromotor is changed by the loads that occur during operation. The aim of the research was to measure this angular deviation in the case of the implemented synchronous drive. With the help of this, it is possible to determine how much load the system can withstand under certain parameters.

High torque and thermal efficiency, durability, reliability, fuel economy, and low emission of carbon dioxide are the factors that made of diesel engine as a preferable engine in passenger transport, trucks and power generation. In contrast, high localized temperatures along with heterogeneous combustion of the fuel-air mixture have made the diesel engine yields a high level of particulate matter and nitrogen oxide emissions. In addition to the problems of diesel engines, the fear of depleting energy sources along with environmental pollution and global warming as a result of using fossil fuels prompted researchers to find many types of alternative fuels. HCNG is a mixture of hydrogen (H2) and compressed natural gas (CNG) that is used as an alternative fuel for diesel engines at varying substitution ratios. The objectives of using HCNG are to maintain or improve engine efficiency and reduce exhaust emissions in addition to the cheapness of this fuel compared to diesel. Many researchers have conducted theoretical and experimental research on the use of HCNG fuel with diesel engines, but there are few literature review studies in this area. Therefore, in this research, the results of a number of pre-prepared studies regarding the performance and exhaust emissions of a HCNG tri-fuel diesel engine were reviewed and summarized. Engine performance is represented by in-cylinder pressure, heat release, brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), brake power (BP), and brake torque (BT).

DC/DC converters are essential parts of an electric car. Converting high voltage to 12 V is the task of the main DC/DC converter. The phase-shifted full-bridge (PSFB) is a popular circuit topology for this role due to its high efficiency. However, designing the PSFB for electromagnetic compatibility (EMC) is a significant challenge during the development phase. Therefore, we conducted simulation-based experiments on the connection between the unintentional parasitic capacitances and the electromagnetic emissions to support the EMC design of automotive DC/DC converters.

Solar energy is an abundance, inexpensive and clean source of energy. Using this energy source can be widely spread as the efficiency of solar systems improves. The main component of any solar thermal system is the solar collector which absorbs the incident solar radiation and converts it into heat. Solar thermal systems are categorised into two major types as air and liquid heaters. A solar air heater (SAH) is used for space heating and crop drying. A solar water heater (SWH) is used to supply hot water for domestic and industrial applications. However, air and liquid collectors are considered as a single purpose collector since the working fluid is air or liquid only. One way to enhance the performance of solar thermal systems is by combining both air and liquid heaters in one facility called dual-purpose solar collector (DPSC). This collector is basically a flat plate solar collector (FPSC) with two sections, one for air heating and the other for water heating. Therefore, it can produce hot air and hot water simultaneously. Using DPSC can attain high temperature, and high thermal performance with a reduction in cost and space. Despite many significant investigations on DPSC, no review paper has been seen. This article presents the different designs and applications of DPSC and the parameters affecting its performance. A comparison between single and dual-purpose solar collectors is also discussed. Moreover, the possibility of integrating DPSC in some automobile manufacturing processes is suggested in this article as well.

Sigmoid functions (growth function, logistic function, evolution function, etc.) are used to describe, study and forecast several phenomena of the life. In some cases (for example, in case of the COVID-19 disease), the phenomenon has several waves, which needs to apply multilogistic (multiwave logistic) curves in order to perform realistic investigation. In product design, the logistic curve can describe the lifecycle of a product. A product lifecycle can be finished by the significant decrease of the market, but in some cases, several new developments and innovations can regenerate the increase of the market by starting a new boom. This renewing process can invoke several waves of the phenomenon, which will make necessary the application of multilogistic curves for the correct study. This multiwave behaviour of the product lifecycle makes this phenomenon very similar to the time history of the COVID-19 disease which also has several waves, because of the newer and newer virus variants. Analysis and comparison of several phenomena described by logistic curves, or bi- logistic, tri- logistic or multilogistic curves can be made easier by the application of the EBSYQ (Evolutionary Based SYstem of Qualification and comparison of group achievements) comparison and qualification system. The similarity between the multiwave characteristics of the product lifecycle and coronavirus time history makes possible to apply several results, skills and methods of comparison and investigation, which were developed and used previously during the analysis of several waves of the disease also for the case of product lifecycle analysis.

In terms of road transportation, the ratio of newly purchased electric passenger cars is increasing to the detriment of internal combustion engine vehicles. According to current assumptions, this process will continue, but the speed and extent of the change are still open questions. The entire road transport sector is just before a very significant transformation and forecasting this conversion is a burning issue. The changes will arise many challenges, among which growing electricity demand is a great concern. It simultaneously appears to shift towards renewable energy sources in electric power generation. In this work, the growth of newly purchased and already used electric light vehicles is investigated based on the example of Hungary. Taking into consideration the latest available data, the spreading of electromobility is forecasted using an exponential model. It is assumed that the annual new electric car's number shows exponential growth until the year when all newly purchased light vehicles will be fully electric. Three different scenarios are investigated in the manuscript: one assuming a slow increase, one calculating with a rapidly spreading, and one between these two other options representing the most likely case based on the authors’ expectations. Calculating the expected numbers of electric vehicles and their ratio among all light vehicles makes it possible to forecast the additional electricity demand. Based on our opinion, it is a very important and urgent issue, taking into consideration the very long investment and realization time of projects aiming at generating surplus electrical power.

Electric and conventional combustion engine cars require a device, the radiator or air cooler, to ensure operation. Although, it is used to cool a completely different part of the vehicle, an indirect heat exchange takes place by flowing coolant through this radiator. Heat transfer conditions are a function of flow, geometry, and temperature characteristics. A common feature of the finned tube heat exchangers is that the flow cross-sections are relatively small and are constructed parallel to each other. This implies that the geometry is the same in these radiators regardless of which part of the device is considered. Therefore, the local in-homogeneities are dependent on the other two factors. The coolant flows in these parallel tubes, transferring the heat from the equipment to be cooled to the ambient air temperature. The present paper deals with the effect of the inlet duct on the flow conditions and indirectly investigates the heat transfer conditions which are investigated by this numerical simulation.

For thermal insulating vehicles usually, lightweight materials are used, such as polymeric foams or microfiber insulations. But, the use of novel so-called super insulation materials can also be a good solution for this. Vacuum insulation panels can be reliable insulators for electric vehicles, too. In the paper, we will give a comprehensive review of possible applications of aerogels, polymeric foams, and microfiber insulations. Moreover, a brief introduction will be given about their thermal properties, especially focused on thermal conductivity and compressibility. Finding appropriate solutions for the aircraft industry is very important. There are several requirements for materials used by aircraft to fulfil the tightening demands, such as low weight, good noise and thermal insulation.

People’s need for comfort has accelerated the development of air conditioning systems. The cooling system is an essential system to analyze since it affects passenger comfort and the vehicle’s transient responsiveness. In this paper, a thermal load estimation has been developed for the Arteon vehicle cabin travelling in Miskolc. The outside conditions include a minimum and maximum temperature of −3 and 35 ℃, respectively, while the air velocity is between 0.83 and 7.5 m/s. The Arteon’s vehicle air-conditioning system plays a crucial part in providing a comfortable environment. The heat generated in the cabin is a combination of passengers, solar radiation, ambient, exhaust, engine, and ventilation. In this investigation, a negative load was applied to the cabin in order to cool or heat it. The air conditioner (AC) loads have been computed for three distinct time periods, namely three days in each summer and winter month. Based on these data, an Artificial Neural Network (ANN) was developed to predict the heat load in the car during the year. The agreement with the theoretical calculations was good even if we used a seventh month, namely September, for verification. The maximum error between the thermal load and ANN was 3%, 5%, and 11% for August, December and September, respectively.

Impingement jet is one of the most important ways to enhance the heat transfer and fluid flow characteristics. The Heat transfer augmentation research has been carried out over the last several decades to enhance the heat transfer augmentation used currently. Although, data is still limited regarding twin jet impingement and heat transfer augmentation using twin jets. This critical review illustrates a very comprehensive analysis of both experimental and numerical. This article aims to provide a detailed review of the twin impingement jets mechanism and the design’s physical knowledge. The article also intends to give a detailed review on using twin impingement applications, where the factors that influence heat transfer are categorized. The impingement heat transfer and characteristics of twin impingement jets are mainly focused on. This critical review aims to confirm the deficiency of knowledge on the impingement of twin jets on flow and heat transfer enhancement and to identify the crucial parameters regarding this issue. This critical review aims to epitomize current advancements in research on the characteristics of heat transfer of twin impingement jets to come up with several possible reasons why the change of parameters and applications of jets can augment the transfer of heat of traditional fluids and come up with a guideline for research in the future. The influence of pulsation frequency on the augmentation of heat transfer was discussed, and it can offer a view regarding the behaviour of heat transfer development and jet flow. Furthermore, the future directions of Nanocoating in the impingement jet techniques need more investigation regarding the deficiency in the literature.

There are many excellent papers published in the international literature which reflect different logistic aspects of automotive production and give numerous useful solutions. Among them, many publications deal with the scheduling and optimization of the logistic activities of the production processes, but most of them ignore the analysis of the effects of the handling machines. This paper gives an overview of the process-based planning concept and its application possibilities in automotive production focusing to equipment selection. This design concept uses an integrated, task-based approach however; it is mainly focusing to the handling processes. By the help of the process-based planning concept the logistic tasks of the automotive production processes can be solved in a more efficient and economical way.

The automotive industry is highly exposed to the changes in the current economic situation. Product development practices must be evolved to exploit the new possibilities. Startups play an increasingly dominant role in the economy through empowering risk-taking and innovative entrepreneurial behaviour. Collaboration with startups in product development leads to particular management challenges. While the automotive industry is sensitive to quality and requires controlled procedures, startups’ risk-taking behaviour can be hazardous in the entire supply chain. Furthermore, the expectations and opportunities of startups and usual firms are different, resulting in conflicts and risks in the product development process. The study investigates the evolution of the automotive supply chain focusing on enhancing the relevance of startups and highlighting critical factors and risks of the transition. The literature on automotive product development raises the consideration of risk management. The paper applied this knowledge base to startups. The goal is to map the factors, which are the opportunities and risks of the startups in the supply chain considering industry experience.

In this paper, focusing on a designated route of public transport in Debrecen, we examine the possibilities of creating a driving cycle representative for the route. The background of the work is, that in the framework of a larger-scale research project we examine the possibility of how to reduce the bus’s emissions by modifying the drive chain of the current diesel vehicle. A dynamic model suitable for performing the calculations was developed, in which the movement of the vehicle in traffic is described by the driving cycle. The data provided by the data acquisition equipment of the bus on the designated route is available for the creation of the special driving cycle. In this paper, we look for the answer to the question: how the difference in data density affects the driving cycle and how it modifies the parameters describing its representativeness.

Mobile robots play an important role in the operation of automatised, flexible manufacturing plants because flexible, reliable and cost-efficient material handling solutions can be performed. The fourth industrial revolution makes it possible to integrate new technologies and tools and transform conventional material handling solutions into high-tech, state-of-the-art cyber-physical solutions. Within the frame of this article, the authors are focusing on two important fields of mobile robot-based material handling solutions focusing on both mechatronics and the logistics of mobile robots. After a systematic literature review, the potentials of mechatronics and logistics-related topics are discussed, focusing on trajectory planning, controlling and Petri-net based simulation of mobile robot-based material handling solutions. The discussed results show that both mechatronics and logistics are important for the efficiency improvement of mobile robot-based material handling solutions.

Future mobility will depend on low-emission technologies to achieve the climate targets sets and to reduce the effects of climate change. Therefore, green hydrogen can be a key component in specific mobile applications in order to provide low-emission mobility. Unlike conventional hydrogen storage, the newly developed Powerpaste does not have high pressure and temperature requirements. The paste-like hydrogen storage system, therefore, enables simplified storage, handling and transport. Likely mobile applications for Powerpaste are car sharing, intralogistics or courier, express and parcel services. These three application scenarios lead to specific requirements for a suitable Powerpaste container. A literature study is conducted to set up criteria which support the selection of a suitable container. The criteria are categorised using expert workshops and evaluated using the methodology of pairwise comparison. The resulting categories for the criteria are application, logistics, recycling and safety. Two exemplary container concepts are compared and evaluated on the basis of the criteria sets: bag-in-box and piston cartridges. The piston cartridge is rugged and suitable for the transport of dangerous goods and enables simple integration into the car. At the same time, the bag-in-box concept is advantageous from a logistical point of view.

The Fourth Industrial Revolution offers new potentials to increase the efficiency, availability, sustainability and transparency of manufacturing systems. The Industry 4.0 technologies are widely used in the field of purchasing, production, distribution and reverse processes to enhance the efficiency from a technological and logistics point of view. The application of these new technologies leads to the transformation of the conventional manufacturing and service systems into cyber-physical systems, where the design and operation of the new, globalised, interconnected and hyper-connected systems and supply chains require new optimisation approaches. Within the frame of this article, the author focuses on the potential of these mentioned Industry 4.0 technologies from a digitalisation point of view. After a systematic literature review, this paper introduces some potential ways to transform conventional manufacturing and related service systems into cyber-physical environment in the field of manufacturing processes in the automotive industry, hyper-connected collection and distribution systems in city logistics and switch pool packaging logistics in Industry 4.0 era, where smart sensors, intelligent tools, gentelligent products, digital twin solutions and edge computing support the transformation.

The European transport sector is evolving rapidly, and so do the challenges associated with its fuel needs. The advanced biofuels of second and third generations based on Lignocellulosic (LC) and microalgae biomass have emerged as promising alternative biofuels producers. The paper reviews the renewable energy scenario and its contribution to the transport sector in the European region. A techno-economic analysis is presented for LC, algae-based advanced biofuels. A SWOT analysis is performed to understand the challenges and opportunities associated with 2nd and 3rd generation advanced biofuels for making them market-ready.

Hydrogen as a fuel can replace non-renewable fossil fuels, however, its explosive properties make it a more dangerous substance than petrol or diesel. This research aims to develop a Computational Fluid Dynamics (CFD) method to model hydrogen gas release at fueling stations. Ansys Fluent software is being used to investigate the formation, dispersion and distribution of explosive atmospheres and gas concentrations. The extent of hazardous atmospheres depends on the operating pressure, the temperature, the size of the leak, the physical properties of the hydrogen and the characteristics of the wind. The model can be useful for the scientific study of leaks and dispersion at the growing number of hydrogen fueling stations. What is more, it can be studied how it can endanger people in these areas. All this can be achieved without any human exposure to the extremely hazardous environment during the simulation.

Rare-earth materials play an essential role in the field of electromobility. These materials are frequently used in automotive components such as electric machines, battery packages, controller units, automotive actuators, and car multimedia applications. The research aims to examine the ecological effects of the rare-earth material usage and carefully analyse the market needs for rare-earth materials. It is essential to investigate how the other fields of the market (like consumer electronics or telecommunication) can affect the field of electromobility regarding rare-earth content usage. Rare earth magnets are key components for tablets, cell phones and many other electronic devices. It is very unlikely that the major electronic device manufacturers are decreasing their rare-earth material consumption despite the increasing demand for e-mobility. Statistic methodologies are used to conclude the rare-earth material usage. The geopolitical situation and the geographical distribution of the rare-earth production are all essential parts of this article. The recycling rates of the rare-earth materials and the rare-earth-material-based magnets are relatively low compared to other base materials in electromobility. The impact of the low recycling rates, together with the increasing demand for rare-earth materials, lead to a business situation which triggers engineering activities focusing on partially or fully rare-earth material free solutions. In this article, the current situation in the rare-earth market is analysed and conclusions are drawn regarding the predicted future situation. The future challenges are also identified, and solutions are proposed as well.

Selecting the most suitable steel grade from the available set is a difficult task, therefore it is essential that the selection is carried out in a planned way. Because of its importance, the theme of material selection has been the subject matter of several research. In spite of the fact that the literature is very rich, there are obstacles in the implementation of theoretical processes in the steel industry that prompt us to review the well-established practice. The aim of this paper is to present an optimisation proposal for the current material selection process, with a special focus on rolled steel products, due to the problems encountered in industrial practice. In our work, we thoroughly studied the literature on material selection methods and related processes and the characteristic features of rolled steel products that could distinguish them from other raw materials. We found that due to these differences, the application of the standard material selection method is hazardous and it needs to be optimised. Our proposed model eliminates the current uncomfortable situation where steel producers, part manufacturers and part designers argue about each other's responsibilities following a less than successful material selection. The model presented in this paper is intended to provide a practical tool for all interested parties in the automotive and mechanical industry in order to avoid design errors and parts deficiency. Our model can be incorporated in the currently valid first-sampling regulations of the automotive industry.

The current cooling systems of internal combustion engine vehicles have several functions; in addition to removing excess heat from the engine, it plays an essential role in ensuring that the engine quickly reaches operating temperature and keeping the passenger compartment at the right temperature. Nanofluids possess better heat transfer properties so that current and future cooling systems can work more efficiently. The common coolant used in cooling systems is water or what equivalent substance; these coolants suffer from a decrease in thermal conductivity, which negatively affects internal combustion engine efficiency. This study presents an experimental investigation using iron oxide (Fe2O3) and tungsten trioxide (WO3) nanopowder suspension at a specific volume concentration in deionized water as proposed nanofluids. Thermal analytical calculations were conducted of the proposed nanofluids under laboratory conditions with validation of the results and comparison with previous studies. The study indicates an improvement in the heat transfer rate, Nusselt number and heat transfer coefficient, drop in the friction coefficient with an increase in Reynolds number, and convergence of the experimental and simulation results confirms the accuracy of the results. The current developments contribute to increasing the usability of new cooling media by the vehicles and the possibility of achieving greater efficiency.

The paper analysis the changing of internal roundness of alternator stators which is caused by different (relatively higher and lower) temperature storage tests and calculated with statistic method. The specific power and efficiency of the automotive alternator can be significantly decreased due to this kind of failure as the extending stator points crash to the rotor, which cannot rotates adequate speed. The main purpose of this publication is to investigate the effect of thermal testing parameters (temperature, running time, set or not with damping element) on shape correctness. In this investigation, a specific algorithm and the full factorial experimental design method are used to plan and execute the experiment. The measurement of the roundness of the specimens is done with a circular and position error measuring equipment. Special improvement ratios are determined from the measured data to clarify the suitable range of testing parameters which results in greater deformity.

The orientation in composite materials determines the mechanical properties of the structure. Different orientations have different usages, and by combining multiple layers with changing orientations, the best mechanical properties can be achieved for the given load case. This work aims to investigate the effects of the different orientations on the mechanical properties of a glass-fibre reinforced composite material used in aerospace components. Multiple specimens were prepared using the vacuum bagging technology with 0°, 45° and 90°orientations based on the warp direction. The laboratory measurements were done with the INSTRON 68TM-10 material testing machine and the GOM Aramis 12M full-field optical measurement system, which works based on the digital image correlation method. The Aramis system enables the real-time tracking and visualisation of the displacement and strain values on the whole surface of the specimen. Under the same conditions, tensile tests were performed on each specimen, and the results were compared. The mechanical material properties of each orientation were determined.

The classical clinch joints are two-layered spot joints; however, several different variants have been developed so far. Although, the technology is capable to join more than two sheets. In this study, aluminium spot joints were produced and examined because in the past few decades, the importance of aluminium sheets is increasing in car body manufacturing due to their low weight and relatively high strength. The aim of this study is to investigate the multilayered aluminium clinched connections from the point of view of forming process, and resultant parameters. Experimental and numerical studies were performed to analyze the process itself and analyze the resultant joint geometrical values which are primarily indicators of the joint strength. In this study, the applied material was EN AW-5754 aluminium alloy, and the total connected thickness of sheets was 2 mm. The joints were manufactured by a TOX clinching tool at the University of Miskolc. The most important parameters of the joints from a mechanical strength point of view are the neck thickness and the undercut, besides the only measurable parameter, the residual bottom thickness, which were analyzed. The cross-sections of the clinched joints were analyzed by microscopical investigations. The joints, and basically the joining by forming process were also analyzed numerically by 2D asymmetrical finite element model to virtually analyze the forming load, material flow inside the clinching tool and analyze the stress and strain state of the joints.

Today, industrial robots play a significant role in the automotive industry. There are several workflows in the industry that can only be solved efficiently and productively with robots. These robots are equipped with various accessories, such as grippers, sensors and, if necessary, an image processing system. There are tasks where traditional robot programming with fixed coordinates is not enough; visual information about the workspace and workpiece is needed. The problem, especially in smaller companies, is that the existing robot needs to be upgraded, for example, with a visual sensor and an image processing system, but this is usually difficult and costly for older robots and robot controllers. The aim of my research is to create a solution that allows a robot controller to be economically equipped with an image processing system that is not prepared for this at the factory. All that is required for the controller to be able to communicate with the outside world via some communication interface. An external image processing system, which can be a standard PC with the appropriate camera and software, is required. The image processing software running on the PC communicates with the robot controller, and the robot program receives the necessary information from the image processing system via the communication channel.

The compressor wheels used in turbochargers have typically been made of aluminium alloy for decades. The primary reason is to achieve the lowest possible rotor inertia. However, while in the past this component was only encountered with filtered air, nowadays, due to developments in compliance with tightening emission standards, various fluids also collide with the spinning blades, which can cause mechanical damage. One such fluid is condensed water in the low-pressure exhaust gas channel (LP-EGR) formulated at cold starts and low-load conditions. This kind of design has been developed to reduce the nitrogen oxide emission and is used in both Otto and Diesel engines. This paper presents a testing method - implemented on a component testbench - and its results for this phenomenon. First, the effect of the volume flow of the condensed water colliding with the spinning blades was analyzed, and then, in addition to a constant volume flow, the speed dependence of the degree of damage was also determined. Next to the visual inspections, the physical changes on the blades were also detected by vibration diagnostic tools, mainly by analyzing the amplitude of the order correlated to the number of blades, from which we can deduce the changed balance level of the rotor.

In many areas of the industry, continuous and rapid changes can be observed, which are setting a unified direction for product design and creation of the product. Classic examples include the spread of modern production equipment, the consecutive research and development of material technology, computer support and development that allows the extension or supplement of traditional manufacturing technologies. The latter includes additive manufacturing technology, which provides a new opportunity to produce everyday products that have a significant impact on serving market demand. Integrated CAD systems have taken their place in the process of product design and development for decades, partially reforming classical design methods and its steps. The optimization processes have emerged in recent years and are becoming more widespread in integrated CAD systems; these include shape optimization, topology optimization, and the new generative design process, all of which provide an effective solution for design engineers in an increasing number of industrial applications, meaning that these methods can be used in numerous areas of industry. Until now, it was not possible to test the designed products during long-term operation in case of the classic rapid prototyping procedures. However, the appearance of metal powder printing and additive technology already allows the long-term testing of designed prototypes and even the production of final products if the deviation from the required properties of the product is negligible. As a result, using the generative design process, design engineers also have the opportunity to create products that seem to be unfeasible. The following article seeks to prove the facts mentioned above based on a case study. The study describes the product or part that has been traditionally designed and manufactured to replace it with new design methods. And finally details and summarizes the steps required to create a new product or solution.

The following paper deals with examining the pressure distribution of hydrostatic journal bearing at different rotational speeds. The application of hydrostatic bearings has a number of advantages, including contactless operation and damping ability, but also dispose limited operation condition at high speeds. With bearing design parameters and limit speed calculations, the required boundary conditions and FEM volume model were set up to analyze the bearing pressure distribution In the ANSYS Fluent system; severe CFD analysis was performed on the reference bearing to confirm the presence of the limit speed. Additional CFD simulations were run for different bearing recess parameters e.g. recess depth, corner radius and number of pockets.

Due to the recent developments and growth in the field of surface engineering, several new coatings and deposition techniques, such as PVD, CVD, and PACVD (Plasma Assisted Chemical Vapour Deposition) are increasingly applied in the industry. Duplex technologies, like the combined processes involving a PVD or PACVD coating and a preliminary plasma nitriding, enhance the mechanical, chemical, and physical performance of the surface layer in a new, efficient way. The objective of our research work is to investigate the tribological behaviour of two, industrially applied duplex treated advanced TiAlN and CrAlN hard coatings, which can efficiently be used to improve the lifetime of the X153CrMoV12 cold work tool steel. Instrumented scratch tests with constant and progressive loading were carried out to compare the resistance of the two hard coatings to scratching, while ball-on disc tests were accomplished to compare their wear resistance. The investigations were supplemented with morphological analysis of the scratch grooves and wear tracks using optical microscopy, while the coatings were characterised with their microVickers hardness and layer thickness determined by the ball cratering method. Results prove a significant improvement of the tribological performance of the tested coatings compared to the uncoated reference material and superior wear behaviour of the CrAlN coating in terms of both scratch and wear resistance.

The comparative tribological study has been performed on hard coatings of a single layer TiBN and a multilayer TiBN+DLC system on X210Cr12 tool steel. The tested coatings are used in industrial practice. The tribological performance was evaluated by instrumented scratch test and ball-on-disc wear test, supplemented by damage analyses based on optical microscopic morphological investigation of the damaged surfaces. The main findings of the research work consist in that the two types of hard coatings show significantly better tribological performance as compared to the uncoated reference material, but the investigated coated systems behave differently against the scratch and wear type loadings. In terms of scratch resistance, the TiBN monolayer showed 10% better performance based on the critical loading causing the coating delamination compared to its DLC top-coated multilayer counterpart. In contrast, the latter one was more favourable in terms of the wear resistance by providing a 30% lower wear rate compared to monolayer TiBN coating and representing a 73% improvement compared to the reference material. The obtained results are useful in designing wear-resistant coatings drawing attention to the importance of the due consideration of the controlling failure mode to achieve the best service life.

The changing environment of development projects requires the renewal of project management tools, including effective information sharing. Reduced development time, modern approaches to project management, pandemic pressure, and new communication technologies enforce improved solutions. The study deals with the evaluation of the effectiveness and utilization of project information-sharing solutions among engineering and management higher education students. Their approach is at high priority both as future project-team members and involved in a joint project of companies and higher education institutions. Based on the responses of 155 students, digitalization seems to be accepted, but the expected role of personal attendance meetings is dominant. The engineering and management students’ approaches do not show significant differences. Cluster analysis allowed different patterns in the sample about the effectiveness of personal and impersonal ways of sharing, but attendance meetings are evaluated as the most important in each cluster. The results can be used for establishing targeted research in the field.

This paper presents the general influence of feed rate on residual surface stresses of carbon steel in high-feed face milling. Residual stresses were measured using the X-ray diffraction technique. The feed per tooth was realised up to 8 mm per tooth. It was conducted that tensile residual stresses are generated when high-feed face milling. Increasing feed rate leads to higher tensile surface residual stresses in the face milling of carbon steel.

Due to Fused Deposition Modeling (FDM), Additive Manufacturing technology offers to produce complex parts, low cost and large material selection; this technique is increasingly used in several industries. There are several printing parameters that directly affect the mechanical and tribological properties of the final part. The objective of our research work is to investigate different fabrication parameters for Polylactic acid (PLA) polymers for gear applications by characterising the ball-on-disk and compression tests. Several FDM printing parameters were considered for experiments, such as temperature, layer height, printing speed, infill pattern and so on. All specimens for the experimental investigations were printed with different printing parameter combinations by using the “Ultimaker Original +” 3D printer. Ball-on-disk tests were performed to analyse wear performance factors of samples, while compression tests were carried out to compare their load-bearing capabilities. The experimental tests were performed several times for each sample and summarised by determining the average values. The obtained results demonstrate that the FDM 3D printing parameters highly affect the wear behaviour and load-bearing capability of the produced parts due to the various microstructural modifications during the manufacturing process. Based on the ball-on-disc laboratory test results, the difference between the highest and lowest average friction coefficient is characterised by about 57%, while this difference reached 46% for maximum compressive force in the case of compression test results. The current research work provides useful guidance for the selection of FDM printing parameters to get better material properties of PLA polymers for gear applications.

In this paper, a fitness landscape analysis of a complex Vehicle Routing Problem (VRP) is presented, and the effectiveness of population-based heuristic techniques is analyzed on this complex problem. The Vehicle Routing Problem is a common optimization task where vehicles deliver products to customers. The task is NP difficult; several heuristic algorithms have been involved in solving the problem. The objective is to select the right algorithm for the task, where the search space analysis provides an analytical answer. In this paper, the analysis of the population-based heuristics is presented. The paper presents an analysis of the following population algorithms: Ant System, Elitist Strategy of Ant System, Firefly Algorithm, Genetic Algorithm. In this paper, the results of the iterations of each population algorithm are analyzed in terms of the followings: fitness values, fitness distances, basic swap sequence distances, Hamming distances, the best solution, and filtered optima. Based on the test results, it can be concluded that the Ant System algorithm proved to be the most effective and the Firefly algorithm is not recommended to solve the presented complicated VRP.

The Vehicle Routing Problem (VRP) is a common logistics problem. The problem was first published in 1959 as the Truck Dispatching Problem. In the basic problem, vehicles deliver the products from a given depot and then return to the depot. The objective function is to minimise the distance travelled by the vehicles. Since the first published paper, a number of variants have been developed that adapt to real logistics demands. This article investigates the optimisation of a complex Vehicle Routing Problem. The following multi-objective optimisation techniques are investigated in the article: weighted-sum method, weighted-exponential sum method, weighted global criterion method, exponentially weighted criterion, weighted product method, bounded objective function method, pareto ranking, Non-dominated Sorting Genetic Algorithm II, Strength Pareto Evolutionary Algorithm, Niched Pareto Genetic Algorithm. The article provides a detailed analysis with the following heuristic algorithms: Ant Colony System, Genetic Algorithm, Tabu Search, Firefly Algorithm, Simulated Annealing.

Optimization refers to finding the optimal value or best possible option. With optimization, the resource utilization can be planned to be the most effective and cost-efficient, especially in the vehicles sector, where cost and quality are both important factors. However, when dealing with complex systems, findings the best solution is considered almost impossible due to the time and the resources consumed. Therefore, optimization algorithms are used to find an optimum solution as much as possible within a relatively short time. The optimization algorithms evolved from conventional mathematical approaches to modern developed methods that use heuristic and metaheuristic approaches. Within the frame of this paper, the authors present a study that describes the effectiveness of three metaheuristic algorithms and show a municipal waste collection case study in Miskolc. After an introduction and theoretical background about the optimization algorithms development, the authors describe three metaheuristic algorithms: genetic, particle swarm, and simulated annealing. Five benchmarks are used to compare the results and consumed time for the mentioned algorithms. A Traveling Salesman Problem case study is solved to find the shortest real route of twenty locations for a municipal waste collection system in Miskolc city center by using the analyzed three algorithms. After that. The results are compared with a random solution. Particle swarm showed the best results, while simulated annealing was the fastest algorithm in the average execution time.

Metaheuristic algorithms have increased in usage in all the scientific fields during the last decades. Since no optimisation algorithm is valid for all optimisation problems, many metaheuristics have been developed for various applications. Accordingly, this paper presents a comparative study on CEC 2020 optimisation problems among different algorithms. The goal is to give an overall sight of selecting a specific metaheuristic algorithm for a particular application. The algorithms in this study are; dynamic differential annealed optimisation, particle swarm optimisation, fertilisation optimisation algorithm, grey wolf optimisation, whale optimisation algorithm, firefly algorithm, artificial bee colony, ant lion optimisation, harris hawks optimisation, and sine cosine optimisation algorithm. The results are discussed in the respective sections with a focus on the convergence behaviour of the algorithms.

Lightweight composite sandwich structures are widely used in the automotive industry, particularly in vehicle body applications, due to their advantageous properties, e.g. low density, high stiffness and high strength-to-weight ratio. The goal of the research was the elaboration of an optimization method for a totally Fiber Reinforced Plastic (FRP) sandwich structure in order to construct a minimal weight structure. The all-composite sandwich panel consists of a hexagonal FRP honeycomb core and laminated FRP face sheets. The article investigates the optimization of the FRP composite layers of the cell wall of the honeycomb core and the face sheets simultaneously. The Classical Lamination Theory (CLT) with analytical expressions was adopted to calculate the stiffness and strength of the sandwich components. The minimization of the total weight of the sandwich structure was the main goal during the structural optimization. Therefore, the design variables were the following: the orientation of the FRP layer for the cell wall of the core; furthermore the number and orientation of the face sheets’ layers. During the optimization, 5 design constraints which related to structure strength criteria were considered. I-sight software was used in conjunction with Excel software to perform the optimization process. Some of the feasible design points were numerically modelled using Abaqus Cae software and showed good agreement with the optimization result. The main added value of the research is the elaboration of the single weight optimization method for a totally FRP sandwich structure.

Improving the fuel efficiency of heavy-duty trucks is essential for sustainable energy supply and future economic development. Consequently, new technologies are needed to enhance energy security in the transportation sector. In this context, this study investigates the optimal design of a composite sandwich panel as a lightweight structure to replace the conventional materials in the bottom panel of a heavy truck. The composite sandwich structure generally consists of an aluminium honeycomb core with two Fiber Reinforced Plastic (FRP) composite face sheets. The goal of this study is to call for new optimum design strategies of the composite sandwich structures to reduce heavy trucks’ body mass. In this work, the orientation of the composite layers and the core thickness were set as design variables for the optimisation problem. At the same time, the total weight of the structure is considered as the optimisation objective. Moreover, the constraints of the optimisation problem are set to be related to the strength limits of the face sheets and the core. The Classical Lamination Theory and the failure equations of composite plates are formulated using Excel software. To solve the optimisation problem, a Multi-Island Genetic Algorithm is applied under the I-sight software environment interacting with Excel. The numerical model is built using Abaqus Cae software. A good agreement was found between the numerical and optimisation results in terms of the overall deformation of the sandwich for this study. It is worth mentioning that the weight of the bottom plate of a heavy truck can be significantly reduced if the proper sandwich face sheets layup and core thickness are determined. The main added value of the research is the elaboration of the optimisation method for the bottom panel of heavy-duty trucks in order to define the optimal combination of honeycomb core and composite face sheets.

Project-based planning and execution have an important role in the product lifecycle. Medium and large-sized companies are executing more than one project simultaneously, usually sharing common resources. Each project has its individual goals to achieve. Creating a company-wide optimal or near-optimal schedule in this complex environment is very difficult. Our paper presents a model to define the problem and a concept of a possible solver. A proof-of-concept of an advanced solver with experimental results is presented.

GPUs no longer only support graphical applications and gaming. These are becoming cheap and powerful tools for scientific and general-purpose computations. They provide a massively parallel environment with the support of a single instruction multiple data (SIMD) programming model. Making finite element calculations is also a time-consuming process in some cases due to many elements or a large degree of freedom. The FEM simulation is essential to check the analytical or measured mechanical stresses, deformations, etc. In making structural optimisation, one needs several iterations and combining the optimisation with FEM, increasing the calculation time. GPU programming is a good solution for this. In the article, we show the applicability of the combination of GPU, optimisation, and FEM simulation.

This article analyses cost estimations with different welding technologies using global and local methodologies. In structural optimisation these costs are the goal functions to be minimised. We consider the relationship between design and fabrication technology, as well as the economy, using optimisation. These three elements work together to assist us in determining the best option. Only those cost elements that are directly relevant to the structural dimensions are considered in the local approach. A real structure’s cost function may comprise material costs, assembly costs, and other fabrication costs, such as welding, surface preparation, painting, cutting, edge grinding, and creating geometry.Welding is the most common industrial procedure for combining metals, but it is also a significant producer of harmful fumes and gases. Depending on the welding technology, the amount of CO2, CO, CH4, NOx, etc., can be different. The global approach considers environmental issues such as global warming, ozone depletion, acidification, eutrophication, photochemical ozone production, and abiotic depletion. LCA is an objective approach for analysing and implementing alternatives to enhance the environment, as well as assessing the environmental consequences of a product, process, or activity.

The goal of the research presented in this article is to create a vehicle dynamics model, with which can simulate the emissions and consumption data of buses. During the research we created a vehicle dynamics model with AVL Cruise software. This is a longitudinal vehicle model that can be used to analyze the behavior of the bus in the direction of travel, considering different losses, resistances, inertial effects of rotating and traveling masses, and wheel grip properties and rolling resistances. Our future goal is to explore the development possibilities of the vehicle and to make a proposal for the development and possible structural transformation of the powertrain elements.

Research on the non-stationary nature of road vehicle vibrations (RVV) led to advances in simulating such processes. Contemporary methods introduced for the analysis of RVV primarily aimed at partitioning the signal in the time- or time − frequency domain, providing differing segments of a signal. However, a degree of dissimilarity, or conversely similarity, is still challenging to find. Hereunder we argue that in some cases, merely a statement of dissimilarity between neighbouring segments within a signal might be well-enough, though from a broader perspective, the assessment of the similarity of discrete Fourier transforms (DFT) may be the next practical step forward. For this reason, the current paper presents the hierarchical clustering of elements of the short-time Fourier transform (STFT) plane from an RVV measurement; secondly, it introduces a clustering validation metric to arrive at an optimum distance metric and a threshold to use in binary hierarchical clusters.

Non-stationary random vibrations gained increasing interest in vibration testing. Often, a changepoint detection procedure handles the decomposition of Road vehicle vibrations (RVV) when analysing the recorded series. Unfortunately, only subjective justifications support the proposed methods, and mainly the validation of the non-stationarity of simulated signals is concerned. Thus, if a detector is inherent to the procedure, it is also recommended to calibrate it. The current paper concerns the Receiver operating characteristics (ROC) of a CUSUM-type algorithm and supplies contextual support by Segment length distributions (SLD).

This paper deals with the formulation of the governing equations of a quarter car model with an energy-based approach using Extended Hamilton’s principle. The derivations are performed with generalized displacements and generalized momenta for a 2 DoF quarter-car model. The latter description of the problem is rarely discussed in the literature. The formulated ordinary differential equations are solved in Scilab software with Sundials/CVODE solver kind. The state-space representation of a 3 DoF system, which has active suspension, is extended with a Linear-Quadratic Regulator (LQR) theory in order to reduce the unwanted vibrations of the road. The main aim of the formulation of the governing equations with generalized momenta compared to the generalized displacements is to directly provide the forces of the system, which gives the ability to establish a control loop easier with the force measurement of the suspension of a vehicle. Since force measurement for the case of suspension of a vehicle is more feasible compared to displacement measurement.

The increased dynamic loading of rail vehicles during the motion depends primarily on their kinematic excitation. For the rotary service units which are attached to railway wagons, the reliability and lifetime can be affected by the increased dynamic load generated by the motion. The article deals with the measurement of the vibration on the radial piston pump at different speeds from 60 km/h to 120 km/h. The dynamic load of the pump also depends on its size, the characteristics of the bogie which vibrates and the place of attachment of the pump to the wagon and/or on the aim for which the pump was designed. For almost all pumps, regardless of the type of bearings used, measuring the vibration acceleration and calculating the effective value of the broadband vibration velocity on components such as bearing boxes is generally sufficient to evaluate the operating conditions of rotating shaft components with respect to trouble-free operation and corresponding lifetime. The magnitude of the dynamic load of the pump is indicated mainly by the characteristic frequencies of the bearings, whose amplitudes are noticeably larger. The article also deals with a theoretical analysis of the vibration severity related to the conditions of mounting and attachment of rotating components, such as a pump and/or compressor, at a moving vehicle that is kinematically excited. It also analyses the need to extend the frequency range to determine the vibration severity of rotary machines towards the lower frequency range.

In the age of modern automotive diagnostic instruments and automotive on-board computers, the human ear is still the benchmark for detecting and judging certain automotive noise phenomena. The human ear is an extremely sensitive, versatile “instrument,” but it does not provide information that can be stored and processed later. The sense of hearing it evokes is subjective, often different from person to person, even for the same noise/sound. Therefore, it is not possible to determine certain defects that provide a more differentiated acoustic pattern using the human ear alone. This publication deals with the comparison of measurable results and subjective impressions. For that purpose, noise measurements were performed on two different passenger vehicles, and psychoacoustic parameters (loudness, roughness, sharpness) and in addition the overall sound pressure level were evaluated. Based on the analysis, it can be stated that the evaluated psychoacoustic parameters can judge the perception of disturbing noise phenomena. So, the claims of the passengers can be strengthened through the psychoacoustic analysis.

The detailed mapping of the rotordynamic properties of a turbocharger is an important tool of turbocharger development, where one of the main focuses is lubricant condition. This is well understandable considering the trend of decreasing viscosity levels of engine lubricants. This article introduces rotordynamic investigations of turbochargers performed on a component testbench. The experiments were carried out with different inlet oil temperatures. The goal was to investigate the effect of oil temperature on rotordynamic properties. The component under investigation was a turbocharger of a 4-cylinder gasoline engine equipped with full-floating hydrodynamic bearings. The application of journal bearings can cause several rotordynamic phenomena at high rotational speeds that are typical of turbochargers. Experiments were conducted on new condition and used conditions (over 50.000 km, in urban traffic) of a turbocharger, where oil temperature varied between 20 ℃ and 120 ℃ in six steps. Lubricant temperature and bearing wear had a noticeable influence on both the synchronous and subsynchronous vibrational behaviour of the turbocharger. The present paper describes the applied testing processes and evaluation methods. Results contributed to ongoing comprehensive research regarding rotordynamic mapping of automotive turbochargers.

Electric vehicles are more and more popular nowadays. This is the reason, why the problem of noise, vibration and harshness of these vehicles is in focus of discussions. This paper presents the results of a study about vibration testing of vehicles driven by electric motor on the one hand and Internal Combustion Engine (ICE) on the other hand. During the tests, carried out on the test rig of the laboratory, vibrations of rolling element bearings have been measured at several rotational speeds in the horizontal, vertical and axial direction. For the measurements a four channels vibration analyser was used. Piezoelectric accelerometers were fixed to the bearing houses by magnets. Acceleration, velocity and displacement signals were recorded in several frequency ranges at various locations of the cars. Special attention was paid to the wheel bearing units. For processing raw vibration data different filters have been used. The authors analysed the condition of the rolling element bearings by using both time signals and vibration spectra. In order to increase the reliability of the failure detection, commercially available post processing methods have been used in the high frequency range. The measured signals of cars driven by electric motor and petrol/gasoline engines were compared on waterfall diagrams. The obtained results demonstrate that vibration measurement is a useful tool for monitoring the condition of rolling element bearings in order to avoid unexpected failures.

Increasing the significance of railway transportation and developing economic and competitive services is one of the key priorities of the European Union’s transport policy. The demand to increase transport safety while minimising energy consumption and pollutant emission requires the design and deployment of innovative railway vehicles and rolling stock. The requirements for vehicle structures call for the design of structures that are adequate in terms of strength and fatigue, with the lowest possible weight, can be manufactured economically and are easy and cheap to maintain. In the manufacture of railway vehicle structures, the use of welding has great significance. The quality of welded joints significantly affects the reliability and safety of welded vehicle components; thus, learning and applying best industrial practices is essential. In our presentation, we would like to present the application of the requirements for the design, manufacture and conformity assessment of railway vehicle structures through the example of MÁV-START IC + type high-speed passenger coach family.

High strength structural steels (HSSS) in medium plate thickness are frequently used as the structural elements of trucks, railway wagons, cranes and earthmoving machines. Since large, welded components are produced in many cases, the use of flame straightening is unavoidable after welding to comply with the strict dimensional tolerances. Due to the not very concentrated heat source, the process can cause significant changes in the microstructure. Among the flammable gases (hydrocarbons), acetylene is typically used for flame straightening. To compensate for the welding deformations, heat source may pass through the part multiple times. Therefore, there is a relatively high risk of the repeated thermal effect reducing the heated area’s strength and toughness. In the present experimental work, the effects of multiple flame straightening were compared between S355J2 + N mild steel and an S960QL HSSS. The thermal cycles were determined by using thermocouples arrangement during real experimental circumstances. Three characteristic peak temperatures were selected for the investigations with the Gleeble 3500 thermophysical simulator: 675 ℃, 800 ℃, and 1000 ℃. The applied specimen geometry was 10 × 10 × 70 mm. The simulated heated zones were analysed by optical microscopic analysis, hardness tests, and instrumented Charpy V-notch pendulum impact tests. Based on the results, using a maximum temperature above A1 during flame straightening is not recommended since a significant toughness reduction can occur in the intercritical temperature range. However, multiple heating in the same location typically does not cause further negative changes and may even slightly improve toughness.

To investigate the application of laser-arc hybrid welding to manufacturing steel bridge members, a series of experiments were carried out. One-pass full-penetration butt joints employing steels for bridge high-performance structures (SBHS500) were fabricated by the laser-arc hybrid welding with a thickness of 15 mm, which applied the specified welding condition based on the previous study to avoid generating cracks and defects. Subsequently, the same dimensional arc welded butt joints utilizing SBHS500 were fabricated. The four-point bending fatigue tests were conducted on the laser-arc hybrid welded butt joints and arc welded butt ones. In order to elucidate the bending fatigue characteristics of butt joints fabricated by the laser-arc hybrid welding, the fatigue strength of laser-arc hybrid welded butt joints were compared with that of arc welded butt joints. The experimental results revealed that the laser-arc hybrid welded butt joints had the same or higher fatigue strength than the arc welded butt joints under the stress range of 250 MPa or more, and no cracks were observed under the stress range of 200 MPa. The fatigue strength of the butt joints using laser-arc hybrid welding was improved compared with those using conventional arc welding, possibly because the hardening due to the rapid heating and cooling around the weld toe in laser-arc hybrid welded butt joints was larger than that in arc welded butt joints.

Arc welding produces several harmful health effects on the welder. The authors wanted to determine the intensity of ultraviolet (UV) radiation as a function of distance from the welding. The research focused on the UV radiation generated during the arc welding process, as it is a widely used process in industrial practice today. Several tests were performed on the gas metal arc welding process (GMAW) during the experiment. The arc welding UV effect investigation was made with three different shielding gases C1 (CO2), M21 (82% Ar-18% CO2) and M20 (10% CO2 - 30% He - 60% Ar) as a function of the arc distance. The used gas metal arc welding (GMAW) process is a common, easily automated technology. In the case of robot welding, the robot and the human operators have to be separated to assure safety. The research focuses on a collaborative workshop where the robots and the human operators are not separated; they are working together. In the collaborative workshop, it needs to assure the safety of the operators with virtual curtains. The danger zone determination is key to determining the virtual border around the welder robot. The goal of the research is the danger zone determination based on the health damage effects. The biggest health-damaging effect of arc welding is the UV effect. The result of the research is the danger zone determination made based on the UV radiation level.

Friction Stir Welding (FSW) is one of the most efficient solid-state joining methods and can be used in many industries. The simulation process can provide the development of temperature fields, metallurgical phases, stresses and strains that can be easily measured during welding. Numerical modelling requires modelling of the interaction between thermal, metallurgical and mechanical phenomena. The aim of this paper is to describe the thermo-fluid and thermo-mechanical analysis of FSW using the finite element method. This paper presents the results of both numerical simulations for an aluminium alloy using the SYSWELD program.

The paper aims to design a simulation of a butt weld made of stainless steel and copper by a laser beam. The concept of the problem solution is based on a non-experimental method of thermomechanical and stress-strain analysis of the laser welding process of dissimilar materials, which can largely predict suitable welding parameters for real experiments and thus effectively reduce welding defects. All simulation steps were performed using ANSYS simulation software. A Gaussian volumetric heat source was used for the simulation. The physical and mechanical properties of the materials are temperature dependent and must be defined in the simulation software. The ANSYS SpaceClaim module was used to create the geometric model. The geometric model is dimensionally identical to the sample used in the real experiment. The initial conditions in the numerical simulation were determined based on the initial state of the experimental sample. Real samples were welded using a disk laser; parameters were set based on simulation. The results of the thermal analysis are used to examine the temperature fields created in the welding process. They are used to optimize welding parameters. According to experimental and simulation results, there is a different maximum temperature in the weld metal on the copper side as well as on the steel side due to a higher coefficient of thermal conductivity of copper. The results of the stress-strain analysis consist of two parts. The first part examines the effect of clamping on the stresses arising in the welding process, and the second part is focused on the overall deformation. Due to the small differences in the values of the coefficient of thermal expansion of the metals used and the small dimensions of the test specimens, the residual stresses and strains are negligible.

The paper aims to investigate the weldability of similar overlapped joints of stainless steel (SS-AISI 304) and copper (Cu-ETP) with thicknesses of 2 and 1 mm in the form of sheet metal. The main criterion was the design of electron beam welding parameters, while several samples were made, varying the welding current in the range of 80–10 mA, welding speed (30–40 mm/s) and beam offset. The samples thus prepared were further analysed by macro and microstructure, the microhardness was measured, and the mechanical properties of the joints were determined, namely the shear strength test. The influence of individual parameters on the weld geometry was monitored. The joints are characterised by the heterogeneity of the weld metal with a large mixing of Cu and SS and the formation of partial porosity. The microhardness of the weld metal was measured in the range 131 - 156 HV0.1. Shear strength was measured and calculated at a range of 552 - 639 MPa. The analysis of the created joints was performed, taking into account the overall quality of welded joints in order to achieve joints without defects and with acceptable mechanical properties.

The paper deals with the production of overlapped welded joints in a continuous and pulsed laser welding process with different welding parameters in order to examine the influence of changing parameters such as: power, focus, speed and length of the welding pulse. Laser welding achieves a high energy density, so there are no special requirements for the cleanliness of the welding surface because all impurities are evaporated before the material is melted. The overlap joint is mainly used for joining thin sheets and pipes. The aim was to find suitable parameters of the proposed technology for welding overlapped joints created of austenitic steel AISI 304 and copper Cu - ETP. In the experimental part, the created overlapped joint with power of 2000 W, welding speed of 15 mm/s and beam focus of 0 mm, where the total power input was 133.33 J/mm met the required criteria based on macro and microanalysis. The weld was realised by continuous welding. Satisfactory welding parameters were used for test specimens, to perform tensile and shear tests. During the tensile strength test, the failure occurred in the heat-affected zone (TOO) of copper due to the softening of the copper by grain coarsening. The strength reached values from 230–240 MPa. The calculated shear strengths were ranged from 409 to 411 MPa. The strength value depends on the degree of mixing of the materials in the weld. Based on the results of the shear test, the proportion of copper and steel in the mixing area proved to be a significant factor in the strength of the welded joint.

Generally, the fatigue strength of a welded structure is characterized by certain factors, which are incorporated in the detail categories and S-N curves as a statistical variation. However, digitized welding production enables the precise control and evaluation of the fatigue-related design and manufacturing parameters at different levels; this can be utilized when applying modern fatigue assessment methods. The fatigue strength of a weldment is usually evaluated based on idealized and standardized factors, but the availability of measured parameters can improve the accuracy of fatigue analysis. In this study, the validity of general design simplifications is compared with actual measurable parameters. Different factors, such as loading, global structure, structural detail, local weld geometry, initial defects and residual stresses, are identified, and their effect on the total fatigue life is evaluated. To exemplify the outcomes of different factors, the fatigue strength of a mobile working machine is evaluated using idealized and measured parameters. The results indicate that the idealized model can produce distinguishing features compared to the real structure, whereby the scatters of individual factors have an essential effect on the deviation in the fatigue assessment results. However, the case study reveals that when the fatigue analysis is conducted using the effective notch stress (ENS) method, the actual weld shape has a minor effect on the results compared to the idealized geometry. Thus, the analysis and efforts must be focused on those factors that have a considerable impact on the reliability of theoretical results in practice and a substantial effect on the quality of weldments.

In the automotive industry there is an increasing demand for the reduction of CO2 emissions, which requires new generations of high strength steels. The high yield strength is originated with the combination of alloying elements, rolling and heat treatment. In the ultra-high strength steel (UHSS) category the microstructure is contain more and more martensite which results higher strength but less elongation. During welding, these properties irreversibly changes by the heat cycle, for example in the heat-affected zone (HAZ) strength reduction can be expected. Because these problems necessary to investigate the weldability of these UHSS sheets. In the automotive industry the most frequently used welding process is the resistance spot welding for thin sheet welding (e.g., in case of chassis elements). This is a precise pressure welding process so it uses pressure force and welding current, which means it has a thermomechanical effect on the base material. Therefore, in this case it has more chance to optimise the parameters for these welding sensitive materials. The present research work aims to investigate the mechanical properties of resistance spot welded joints of 1200 and 1400 MPa tensile strength steel sheets. The heat-affected zone softening and other weldability problems are investigated too. Very important to know how can the mechanical properties improve by technological parameter optimisation, so in this article it is examined and the results are written too. Previously the resistance spot welded joints properties were investigated in case of lower strength steel sheets like DP1000, DP800 and DP600. In this article a comparison is made between resistance welded joints of steel sheets from 600 MPa to 1400 MPa joint properties. This comparison basically focuses on weldability, mechanical properties, and welding technological modifications, and according to these, some designing conclusions are written.

Nowadays, the automotive industry shows an ever-growing need for the application of high strength materials. The high strength steels are one of the most important materials used at present; these steels have excellent properties such as high yield strength and low weight. These properties are insured by their versatile and complex microstructures. The use of these steels is advantageous from the standpoint of economic application and fuel consumption. Furthermore, the weight loss of vehicles results in the reduction of pollutants and greenhouse gases emissions. Besides that, the application of high strength steels also causes an improvement in strength, stiffness, and other performance characteristic. In spite of the aforementioned advantages, there are still difficulties with their wider use due to their limited formability and weldability. The welding of high strength steels can be a great challenge because of cold cracking sensitivity, reduction of strength and toughness of heat affected zone and filler metal selection. To take advantage of the outstanding mechanical properties of high strength steels, it is very important to select the appropriate welding method with the exact welding parameters.In the present research work the effect of the filler metals on microstructure and mechanical properties of a high strength structural steel (Alform 1100M x-treme) having 15 mm thickness welded by gas metal arc welding was investigated. The chosen filler metals were the Böhler Union X96 (undermatching condition) and Böhler alform 1100 L-MC (matching condition). During the welding experiments, the t8/5 cooling time was regulated. Based on our former investigations (physical simulations on the examined material) and recommendations in the literature, the chosen t8/5 cooling time was 5 s. The welding parameters were determined based on the cooling time. After welding, different destructive and non-destructive investigations (optical microscope, hardness tests) were performed to compare the microstructure and mechanical properties of the joints made by different filler metals.

Nowadays, the safety and the economic perspective are given special attention in the production of welded structures made of high-strength steels (HSSs). One of the problems in welding of HSSs is the cold crack sensitivity, which is closely related to the residual welding stresses. These can be controlled by the use of preheating, the correct choice of welding sequence and the post-weld heat treatment (PWHT). Another problem in welding of HSSs is providing adequate toughness and hardness in the heat-affected zone. These can be controlled by heat input, more specifically by limiting the heat input. For these steels, the risk of reduced toughness from a manufacturing point of view is higher than the risk of cold cracking.Classical techniques of fracture toughness evaluation, such as determination of the plain-strain fracture toughness or the critical value of the crack-tip opening displacement, are complex methods. The necessity of fracture mechanical test is inevitable, applying notched and precracked specimens. The determination of the absorbed specific fracture energy (Wc) and/or the notch opening displacement (NOD) is basically simpler. Notched cylindrical tensile specimens can be applied, characterised by different notch radii.S960QL high strength steel and its welded joints without preheating and with 150 °C preheating temperature were examined; NOD and Wc values were determined and compared. Conclusions belong to the effect of the preheating and the sensitivity of the HSS, as well as the reliability of the applied material characteristics were drawn.

Tubular members are extensively nowadays used in the construction of many vehicles due to their excellent properties like high torsional rigidity, high strength to weight ratio, and less surface area. Also, it helps in reducing expenditure during the fabrication and installation of the big effective designs. The tubular members are subjected to different cyclic forces leading to plastic deformation of chords, material degradation, fatigue cracks due to which tubular members undergo severe damage, and finally, will lead to the failure of the whole structure. The overlapped tubular joints and simple gap joints can be used as the joint type in tubular members.In this study, the fatigue analysis of overlapped and non-overlapped K-type tubular joints was carried out using the 3D fatigue FE analysis method to investigate the fatigue performance. The 3D fatigue FE analysis based on continuum mechanics and elastoplastic cyclic hysteresis constitutive equations was carried out in 3 steps. Firstly, thermal load i.e., temperature histories, were calculated using thermal analysis secondly welding residual stress and welding deformation were estimated using thermal load as initial data in the mechanical analysis. In the 3rd step, the residual welding stresses and welding deformation were utilized as initial data to determine the fatigue life The S-N curve was drawn from 3D fatigue FEM analysis results.