Smart Innovation in Mechanical Engineering

This research used aluminum 6061 with the dimension of 150 mm length, 50 mm wide, and 10 mm thick, milled to form 45° edge angle for joining process. The shoulder probe was simply designed and made from hardened EMS 45 Probe treatment is carried out, heated to a temperature of 900 degrees Celsius, hold for 5 h to get the austenite phase, then cooled quickly with water to get the martensite phase to get a hardness of 62 Hrc. The micro structure and temperature distribution were observed and the MgO substance was measured using X-Ray Diffraction. Using a scanning electron microscope, the micro hardness and tensile strength tests were performed. This experiment sought for the correlation of the material’s micro structure, temperature, and tensile stress. In this experiment a simple milling machine was used, the feedrate speed can be adjusted automatically, a JIG Pixture was used so that it remained strong and did not move. The adjusted parameters were the feedrate speeds that ranged from 10 mm/min, 15 mm/min, and 30 mm/min and the spindle rotation speed set constantly on 2000 rpm. 6061 aluminum is used at both ends, 150 mm is made at a 45° angle so that solid welding can be carried out with good results, then a hole with a diameter of 2 mm is made for the data logger thermocouple. 24 thermocouples were installed on the material to measure the temperature distribution. The result, of the research can be carried out well the tensile stress score was 154.67 MPa, acquired from 10 mm/mnt feedrate speed. The highest temperature distribution recorded on such feedrate speed was around 223–484.9 °C and the lowest one was 242–311 °C with the a tensile test score at 125 Mpa. Those results were clarified by the a micro and macro structure formed.

The femoral stem is part of an artificial hip joint arthroplasty that is installed through surgical procedures to replace the problematic hip in the patient. The femoral stem part was manufactured using a hot forging process. Even though the forging die material was selected from hot working tool steel, the changes in the die geometry outside die closure tolerance may have occurred after numerous forging cycles. This can lead to defective femoral stem products. A simulation using ANSYS LS Dyna was performed in this research to determine the tool's life. The simulated forging pressure of 250 tons and loading speed of 300 mm/s were applied on two different workpieces of AISI 316L plates and Ti6Al4V bar. The simulation provides maximum equivalent stress and total deformation of the workpieces. Archard Wear Equation was then utilized to calculate the total wear per cycle of the forging dies based on those data. This tool’s life in terms of the maximum number of cycles of the dies was determined by dividing the die closure tolerance database in the ASTM-A521 standard by the total wear per cycle. The results show that the tool life of 6210 cycles was found for AISI 316L plate workpieces of 12 mm thickness and 3899 forging cycles for Ti6Al4V bar of 24 mm diameter. This condition happened because a lower flashing area was being generated, which led to less wear on the die trim line with the smallest plate thickness or bar diameter. Meanwhile, for other dimensions of plates and bars, a lower tool life was estimated before the dies were unusable.

Dent defects are typical damage in subsea and land pipelines. Such damage threatens the safety of pipeline networks and reduces the efficiency and effectiveness of fluid transportation. Consequently, planned pipeline development must adhere to the Association of Adhering to the American Society of Mechanical Engineers (ASME) standards, particularly ASME B31.8. This study employs the finite element method to analyze failures in pipeline networks caused by dent defects in pipe segments, explicitly focusing on the API 5L X80 pipe. The API 5L X80 pipe segment design, created using Computer-Aided Design (CAD) software, is further analyzed using Ansys software. This analysis includes variations in the displacement and the number of indenters. The outputs of this study are Von-Mises Stress, deflection, and plastic strain. Analysis of dent defects, considering displacement variations at a specified depth for the indenter, revealed that the most significant stress occurs in the impact area between the indenter and the pipe. This stress value can be a reference for analyzing real-world pipe failures, especially in predicting the location of the most significant failure in pipeline construction.

The important role of circular cylinders in improving the Savonius wind turbine performance was demonstrated experimentally in this study. This was carried out by placing circular cylinders in 3 (three) configurations, namely configuration-A: circular cylinder is placed in front of the returning blade with a constant distance S/D = 1.4; configuration-B: a circular cylinder is placed beside the advancing blade at various distances Y/D = 1.27, 1.42, 1.61, 1.82 and 2.00, and configuration-C: is a combination of the two configurations. The Savonius wind turbine used in this study is made of PVC pipe, which is split into two with a diameter of D = 165.2 mm and a height of H = 294.4 mm equipped with a shaft having a diameter (b) = 19 mm. In this experiment, the turbine torque is measured using a rope break dynamometer to obtain the power coefficient (CoP) and moment coefficient (Cm) as a function of the tip speed ratio (TSR). For a wind speed operated at 5 m/s, the results show that for configuration- A, the presence of a circular cylinder effectively improves the turbine performance, where the CoP of the turbine increases by about 19% at a TSR of close to 0.6 relative to a conventional turbine. As for configuration B, not all Y/D distances can improve turbine performance, but only at Y/D = 1.42 and 1.61. The highest increase in CoP was obtained at a distance of Y/D = 1.61, with an increase of more than 25% at TSR = 0.69 compared to a conventional turbine. On configuration-C, the circular cylinder installed at Y/D = 1.61 and 1.82 caused the improvement of the turbine performance, where Y/D = 1.61 gave an increase in CoP of about 27.8% at TSR of about 0.63 relative to the conventional turbine..

Laterite processing is experiencing very rapid development through pyrometallurgy and hydrometallurgy. This development is also followed by the issue of green processing, so research on green laterite processing is more focused. In connection with related issues, this research is the beginning of the development of mineral processing with organic solutions, such as citric acid and monosodium glutamate, in hydrometallurgical processes from ferronickel processing by-products. Based on ICP, XRD, and SEM–EDS data, the use of organic solutions is very effective in mineral processing. Still, it needs development for organic acid solutions that dissolve almost all elements. In contrast, organic base solutions still require expansion to increase the recovery value, but this solution is more selective in reduction.

Additive manufacturing technology has made remarkable advancements, enabling the development of innovative structures by leveraging existing constraints. A notable area of exploration lies in lattice structures, which offer a promising alternative to solid components. Among the various lattice designs, the body-centered cubic (BCC) structure has gained popularity. Typically, BCC structures comprise diagonal struts, with equal diameters. In this study we propose a control anisotropic strategy by combining BCC and Crossing Cylinder (CC) structure in order to improve characteristics regarding shear and normal Young's modulus. This study aims to investigate the effect of varying the diameters of the center struts of CC and diagonal struts of BCC on two key parameters: the effective Young's modulus and the Zener anisotropic index A. To achieve this, a homogenization technique is employed, allowing the derivation of a stiffness matrix that characterizes the lattice. Subsequently, the Zener anisotropic index A and effective Young's modulus are computed based on the stiffness matrix. To establish a controlled comparison, a specific control strategy is implemented by systematically altering the ratio between the diameters of the center and diagonal struts. This ratio is maintained at values greater than 1 and less than 1 to ensure diverse structural configurations. The results of this research demonstrate that a ratio of 2.5 between the center and diagonal strut diameters yields the most favorable outcome, as evidenced by an obtained Zener anisotropic index A value of 1.08.

Bearing are machine elements that function as support elements in rotating motion in machine construction. Bearing failure will significantly affect machine performance, therefore it is necessary to monitor the failure growth. This research conducted an experimental study of bearing failure that considered 4 types of experiment variables as factors affecting the natural frequency of bearings, namely bearing type, rotation speed, scratching depth, and scratching location. The scratching shape is deliberately given to the bearing part using laser cutting machine as the failure representation. Scratching was machined on the inner ring raceway, outer ring raceway, or roller element part of the bearing. The Design of Experiment (DOE) used the Taguchi method which aims to get smaller number of trials but could get optimum results. Its experiment was designed with 4 variables and 3 levels and was properly tested on rig testing. The frequency spectrum of machine defect characteristics was measured using a vibration analyzer. The interpreting process and mapping of the frequency characteristics of bearing failure for BPFI, BPFO, BSF, and FTF are using omnitrend software. The resulting research shows that the greater scratching depth causes an increase in the amplitude value of the defect frequency characteristic. The bearing shaft rotation value affects frequency value of the measured bearing defect characteristics.

The strength of the vehicle chassis structure is designed to be able to withstand the load that is applied to all sub- components of the vehicle and its cargo. Therefore, there is a need to select the use of the appropriate chassis structure. This study aims to analyze the performance and safety under static and dynamic load parameters that affect the fatigue life of the MEvITS ladder frame chassis structure. The static load analysis is done by applying the load of all vehicle component weights and also the torsional load. Loading of vehicle weight components is carried out to determine areas that experience maximum stress and a small critical point of safety factor. The torsional load is applied to determine the torsional stiffness by applying equal force values to the two front suspension brackets in the reverse direction, the positive and negative vertical axes. The dynamic loads are performed by applying random excitation to the chassis from road roughness according to ISO 8606. Random vibrations are performed to analyze the response of the chassis from random excitation to determine the fatigue factor of the chassis. Modal analysis is also carried out as input in the random vibration of the natural frequency and the shape of the chassis modes. 3D modeling design of the MEvITS chassis is using Solidworks. The static structural analysis, torsional load, modal analysis, and random vibration are performed in Ansys software. The MEvITS chassis has a safe condition under static loads with a safety factor of 1.3038. Besides that, the MEVITS ladder frame chassis also has low torsional rigidity with a value of 985.488 Nm/deg. then dynamic loading, the chassis shows good performance to resist random excitation. The factor of safety from fatigue due to random excitation is 73.

One of the highest components of disability is difficulty in walking, which is caused by disorders of the lower limbs due to disease and joint injuries that occur in athletes. Ankle Foot Orthosis is a tool used to overcome this limitation. Therefore, designing the orthosis with biomechanical aspects and user comfort is very important. This research has been done by examining the effects of changes in structural mass on articulated and non-articulated AFO types, and this simulation is used to determine the dynamic response that occurred. ANSYS Workbench software was used in the simulation, and a dynamic load of a walking human with a gait cycle was used. Finally, the AFO prototype uses the 3D printing method based on the optimum design for user convenience. The results showed that Articulate AFO has higher stresses and deformations than non-articulated. Still, for each system, the stresses tend to decrease from 2 to 5 mm thick, but paying attention to heavy aspects is necessary. The final design for non-articulated is 3 mm, while for Articulated, it is 4 mm.

The implementation of a control system for vacuum toilets in train carriages is essential to address the drawbacks associated with conventional toilets, including high water consumption and complex maintenance requirements. This research focuses on developing a design of PLC-based Control System for Vacuum Toilets, utilizing a pressure transmitter and a Programmable Logic Controller (PLC). The pressure transmitter, with a scale ranging from −1 to 0 Bar, generates a signal between 0.5 and 4.5 V. This signal is processed by the PLC, which analyzes the data and generates output signals for the actuator. The actuator, a solenoid valve, controls the flow of water, air, and waste by opening and closing accordingly. The target pressure value of −70 cmHg is maintained to ensure efficient operation of the vacuum toilets. By implementing this PLC-based control system, water conservation is enhanced, and the challenges associated with complex piping systems and excessive water consumption in conventional toilets are overcome. The system aims to improve sustainability, efficiency, and maintenance ease in train carriage sanitation.

ZnO nanoparticles gathered so much attention from researchers in the past few years due to their advantages in many fields, such as photocatalytic activity and medicine. However, producing ZnO nanoparticles has still been challenging due to its natural agglomeration behavior. One of the methods that can be used is electrospray. This method offers a low evaporation temperature and produces a high-yield material. Regarding the process used, electrospray, several parameters must be considered; one essential thing is the colloidal precursor solution. The high stability of ZnO colloids made from zinc acetate dihydrate dispersed in ethanol as a solvent is rarely discussed. The ZnO-colloid was prepared using distillation equipment and lithium hydroxide as the source of alkali. The effects of operation parameters (sonication time) and alkali concentration added in producing the ZnO colloid were investigated in this study. ZnO Colloid with a good stability agreement comes with 0.1 M zinc acetate dihydrate (ZnAc) concentration and 0.14 M lithium hydroxide ratios, which has a zeta potential of -14.4 mV and 0.324 mS/cm conductivity.

The development of Active Magnetic Bearing (AMB) technology for gas turbines has made significant strides. Initiatives like the Versatile Affordable Advanced Turbine Engines (VAATE) program, in collaboration with DARPA and NASA, aim to enhance gas turbine engineering for efficiency, cleanliness, intelligence, versatility, and durability. AMBs have emerged as superior to rolling element and foil bearings due to their temperature, speed, shaft thickness limitations, and shorter lifespan under heavy loads. AMBs are more suitable for large machines operating under high loads and relatively lower speeds than foil bearings. The research introduces a two-degrees-of-freedom model for AMB systems. The modelling involves two identical electromagnets and simplified equations. The model also considers external forces, including sinusoidal forces from motor vibrations, centrifugal forces from shaft unbalanced assumptions and static forces. The system output is represented by eccentricity. The AMB design adheres to SKF standards for conventional bearings. The rotor model is simulated using MATLAB SIMULINKTM, and the Automatic PID Tuner App is used to find control values based on the created transfer function. System stability is analyzed using the Nyquist stability criteria, focusing on the input rotation speed range of 100 RPM–459 k RPM. Higher motor rotation rates contribute favorably to the rotor's ability to remain centred within the stator. Higher motor rotation rates contribute favorably to the rotor's ability to remain centred within the stator. Specifically, the PID controller exhibits excellent resistance to various external forces. Static tests assessed the system's ability to bear loads, where forces ranging from 100 to 400 N were applied to the rotor. However, adding a 400N load to the rotor has exceeded the value of $$\text{1,5}\times {10}^{-3}$$ 1,5 × 10 - 3 m as the maximum eccentricity threshold. As a result, the maximum load that can be applied to this design is 388 N, with the resulting eccentricity being $$\text{1,48}\times {10}^{-3}$$ 1,48 × 10 - 3 m.

This study aimed to investigate how the performance of the Savonius wind turbine, characterized by blade diameter (D) of 165.2 mm, end plate diameter (Do) of 320 mm, and shaft diameter (b) of 19 mm, is influenced by the introduction of D-type cylinders as disturbances. These cylinders were added with various cutting angles (θs) of 0°, 53°, and 65°. The research was conducted using a 2D simulation using FLUENT 2021 R2, operated at a wind speed of 7 m/s or equivalent to the Reynolds number (Re) = 1.5 × 105. A circular cylinder is placed ahead of the turbine at a distance where S/D = 1.25 and y/D = 0. The outcomes indicated that incorporating a cylinder with specific cutting angles can lead to an augmentation in the maximum power coefficient value of the turbine. The maximum power coefficient value of the turbine (Cpmax) with D-53° type disturbance is 0.18737at tip speed ratio (λ) = 0.6. This value is 1.025 times greater than that of a conventional turbine. But unfortunately, the placement of the D-0 type and D-65° type cylinder in front of the turbine makes the maximum power coefficient of the turbine only 0.17363 and 0.16259, which is 5 and 11.06% lower than the conventional turbine one.

Polymer Matrix Composite is a composite material with synthetic fibers that is widely used in industry. Polymer matrix composites reinforced with natural fibers are called biocomposites. Biocomposites can be used as the best alternative because they are environmentally friendly, biodegradable, corrosion resistant, non-toxic and have high mechanical properties. The biocomposites to be used for this research are banana fiber, melaic anhydride polypropylene (MAPP) with a composition of 10 Wt% banana fiber, 5 Wt% MAPP and 85 Wt% polypropylene. All these materials were mixed and extruded to form pellets. The biocomposite pellets were injected using an injection molding machine. The molded products were subjected to tensile test with ASTM D 638-03 type V standard, and impact test with ASTM D 256-04 standard. This study will optimize the process parameters of the injection molding machine to find the optimum tensile strength and impact strength using the Taguchi grey fuzzy method with an orthogonal matrix L27(34). The process parameters that are varied include barrel temprature, injection pressure, holding pressure, and injection velocity, each of which has three parameter levels. From this research, a combination of injection molding process parameters that can significantly increase tensile and impact strength is obtained, with Barrel temperature 205 °C, Injection pressure 50 bar, Holding pressure 40 bar, and Injection velocity 75 mm/s.

The mold was designed for helmet shell made from biocomposite with a material composition of 10% banana fiber, 10% Maleic Anhydrite Polypropylene (MAPP) and 80% polypropylene. Based on SNI 1811-2007 Mold components are prepared with dimensions according to the SNI standards. Based on the requirements set out in the standards, the helmet shell must meet the impact and penetration tests. The design is intended to determine the thickness of the helmet shell. An impact simulation is carried out with the help of Ansys software with thickness variations from 2 to 6 mm. The simulation results show that the thickness of the shell from 4 to 6 mm meets the requirements, which is indicated by an acceleration drop that does not exceed 300 g. Furthermore, to determine the resistance of the helmet shell against the indenter weighing 3 kg, which is suspended from a height of 1.6 m. The thickness of the helmet cover that complied was 5 and 6 mm, which was shown by the thickness of the shell not being penetrated by the indenter. Next, a helmet shell mold with a thickness of 5 mm was designed, starting from the manual calculation of the required clamping force of 1367.96 kN. And with a melting temperature of 163 °C bicomposite material, the required cycle time is calculated as 129.38 s. The design is tested with the Autodesk Moldflow simulation, the required injection time of 12.43 s, with a filling confidence level of 100%, and the injection pressure is 8.789 MPa.

The ever-increasing of complexity of a product or systems development has given rise to a development framework such as Model-based Systems Engineering (MBSE). To be able to understand the potential of MBSE implementation in Indonesia, several research studies have been conducted in ITB. An initial literature study has been performed to map the potential of future research on MBSE. A survey on the development of technological products is performed to map the existing conditions and the needs for the future.

A suspension system is designed to attenuate vibrations and enhance passengers’ comfort levels when a vehicle traverses uneven road contours. With additional power to control the actuators’ force, the active suspension system produces better ride quality than passive suspension systems. System modeling will be carried out using a quarter-vehicle model with a disturbance input form of a step input of 0.1 m. In this study, the control system used is the PID controller, with the parameters of the controller being tuned using the Back Propagation Neural Network-Genetic Algorithm (BPNN-GA) metaheuristic method employing MATLAB R2022b software. In this method, BPNN is used to produce a network that represents the correlation between controller parameters (i.e., Kp, Ki, and Kd) and system response (i.e., Integral Times Absolute Error (ITAE)). The ITAE value represents the value of Settling Time (Ts) and Peak Overshoot (PO) in a damping system. Next, the Genetic Algorithm (GA) is employed to determine the best BPNN's network with a minimum MSE (Mean Squared Error) value. The performance of BPNN-GA is then compared with Ziegler Nichols method. The best BPNN’s network is obtained with five hidden layers, ten nodes in each hidden layer, and the satlin activation function achieving an MSE training value of 1.6477 × 10–8. The most optimum Kp, Ki, and Kd values are identified through the BPNN-GA method, namely 809193, 621978, and 243984, with a settling time (TS) value of 1.33 s and a peak overshoot of −0.00834 m, along with a Root Mean Square (RMS) value of 0.5747 m/s2. Moreover, in accordance with the ISO 2631 standard, the active suspension system model is classified as slightly uncomfortable.

Manure is the second largest source of greenhouse gas (GHG) emissions from agriculture. A sufficient method for handling manure is needed. Meanwhile, the need for construction materials and economic and population growth are rising. This study aims to tackle both problems by utilizing cow manure mixed with clay as bricks using wet torrefaction and solid–liquid separation to reduce the amount of untreated manure and supply construction materials with greener and improved clay bricks. Cow manure was treated using a wet torrefaction process, heating the manure at 100, 120, and 140 °C, and then left to dry. The dried manure was then mixed with clay, molded, dried, and then baked to produce baked red clay bricks. The bricks were then tested for their compression strength and water absorptivity to determine the relationship between wet torrefaction parameters and brick characteristics. After the tests were completed, it was found that mixing cow manure into bricks increased the compression strength by up to 400% compared to pure clay brick and water absorptivity by up to 150%. Even though the strength of these bricks was increased, utilizing them as conventional construction material is not recommended. Instead, breathable façade material is more favored. Alongside solid products, torrefaction also produced liquid products rich in nutrients. Previous research showed that the nutrient content was sufficient to be made as liquid fertilizer. These results showed the possibility of implementing torrefaction of cow manure to reduce waste and upgrade the products’ value.

Tool flank wear and surface roughness are considered as the most impactful parameters that influence the quality of the workpiece. However, those parameters must be measured directly after the machining process is complete. Therefore, this study proposes an online monitoring application with flank wear and surface quality prediction system to monitor them in real-time. Unlike other monitoring systems widely available in the market, the designed monitoring system was created using open-source software without needing any subscription. Moreover, the prognosis system was built with the combination of multilayer perceptron (MLP) and k-nearest neighbors (kNN) algorithms. The MLP was established to predict the flank wear value, resulting a model with accuracy of 0.982. Furthermore, the result will be normalized and later used to classify the surface quality into three different classes using kNN, resulting in 100% accuracy. Afterward, those algorithms were explicitly implemented into the monitoring application. The system was evaluated in real-time for different machining parameters and can achieve a 88.2% accuracy. This study is expected to improve the possibility of advanced technology implementation, especially in small and medium-sized manufacturing enterprises.

Leaf springs are designed to reduce vibrations and shocks during dynamic operation of vehicles. However, leaf springs can experience various types of damage, such as breakage or fatigue, which can lead to suboptimal suspension performance and potential damage to other vehicle parts. In this manuscript, we explore the possibility of enhancing chamber clearance in leaf springs as a potential design solution to tackle these concerns. We propose a development approach that involves simulation-based design using CAE (Computer Aided Design) software and FEA (Finite Element Analysis). The development presses commence with creation of a comprehensive 3D design for the leaf spring. a meticulous evaluation of initial design is then undertaken, and improvement is made. Following this design optimization on chamber dimension, the prototype is manufactured and tested using method simulation static, simulation dynamic, vibration test, and durability test. The result of the study shows that simulation result of fatigue lifespan, it’s increasing 180.000 cycles to 1 milion cycles. The vibration test on sinusoidal road shown the vibration of prototype is not change compared with the original leaf spring. Therefore this study contributed to enhancing the leaf spring durability without decreasing the comfortability of the suspension.

The commonly object used as a review regarding of biofouling invasion in previous research was ship made of steel. Therefore, in this study a 1 GT wooden fishing vessel with 8.00 m in length, 2.00 m in width, and 0.90 m in height is used to obtain its performance during the invasion of biofouling, include the ship stability, ship resistance, and the growth of the macro fouling. The methods used is experimental methods and numerical simulation using Maxsurf. In the first three, four, and six months, the average adhered macro fouling thickness under the draft is 3, 5 and 7 mm successively. The most growth of biofouling occurred on the planking joint and on the rudder compared to other area of hull. However, in a square of 10 × 10 cm, there were around 52 barnacles in the first three month after the ship was launched. This continued to grow approximately 33 barnacles after a month later. Finally, in the sixth month, total barnacles on the hull reached roughly 110 barnacles. Meanwhile, total resistance of the vessel before the invasion of biofouling was 3.1 kN, then it increased to 3.2 kN after 3 months during the invasion. In the following month, it gradually went up to 3.7 kN, and roughly 6.7 kN in the end of sixth month. The stability criterion of the wooden fishing vessels before and after the invasion meet the requirement of IMO.

This study presents a novel approach to identify the optimal parameter to develop a superhydrophobic coating on SS400 carbon steel substrates by stearic acid combined with zinc oxide coating. The surface modification involved chemical etching and chemical bath deposition using stearic acid with varying etching times, stearic acid concentrations, and stearic acid to zinc oxide mole ratios. The optimum value of surface modification on the contact angle and water sliding angle was investigated using Taguchi’s method combined with the assignment of weight to convert a multi-response problem into a single-response problem. The Fourier Transform Infrared (FTIR) spectroscopy result indicates the successful deposition of stearic acid on the substrate. The analysis of variance (ANOVA) result showed that the stearic acid to zinc oxide mole ratio significantly enchants the water contact angle. Optimum conditions were obtained from the multi-response performance index (MRPI) of the water contact angle and water sliding angle resulting in 60 min of etching time, 40 mM stearic acid concentration, and 0.08 stearic acid to zinc oxide mole ratio. The confirmation experiment that was conducted using optimum conditions resulted in a 155.6° water contact angle and 34.5° water sliding angle which is considered reproducible based on the evaluation conducted using the confidence interval that overlaps between the predicted and the confirmation experiment.

Carbon dioxide is the primary anthropogenic greenhouse gas. The rapid economic growth increased energy demand and fuel consumption, especially fossil fuels such as oil, coal, and natural gas. During their combustion, a large amount of CO2 is released into the atmosphere, which harms the environment and causes global warming. In this work, the bubble column reactor (BCR) was used to absorb CO2 with the carbon mineralization process because it is one of the most widely used multiphase reactors in the industry for gas–liquid reaction systems. Even though a bubble column reactor is one of the multiphase reactors that is easy to construct and operate, scaling up a bubble column reactor is difficult. Scalling-up was conducted by a similarity concept which is relatively simple and straightforward with three parameters used to assess the similarity between two columns (i.e., the ratio of liquid height to column diameter (H/D ratio) to obtain geometric similarity and superficial gas velocity (SGV) and superficial fluid velocity (SLV) to obtain both kinematic and dynamic similarity. This work was conducted using two bubble column reactors, having 7 and 11 cm inside diameter, respectively. Therefore, in this work, a simpler method will be developed to carry out the scale-up of a BCR in the presence of a reaction on the column. Thus, a concept widely used in implementing scale-up, namely the concept of similarity, will be used.

Cutter Suction Dredger (CSD) is a type of dredger which works hydraulically by using a slurry pump to move material to the disposal site. In the selection of slurry pumps, the calculations used are not the same as those of pumps in general. This is due to differences in the characteristics of the fluid, especially its density. In addition, because pump performance data generally uses water as a fluid, a performance correction calculation is needed to obtain the appropriate value. In this project the aims are to identify the characteristics of the fluid, select the slurry pump and design the impeller based on API 610 standard. The stages in this project are divided into calculation; selection; and design. The results showed the slurry fluid has a characteristics, specifically: Density of 1269 kg.m−3; Specific Gravity of 1,269; and Dynamic Viscosity of 0,0,016,252 kg.m−1.s−1. The Head effective installation analytically is 58.215 m and numerically, using Pipe Flow Expert software, is 58,216 m thus resulted error rate of 0,0023% within the allowable limit < 2%. Therefore, in this CSD project, the slurry pump used is Shijiazhuang Nainater Slurry Pump Co., Ltd 450 WN with moderate-speed impeller type; Blade Inlet Diameter 0,631 m; Blade Outlet Diameter 1,263 m; Blade Inlet Angle 15, 98°; Blade Outlet Angle 25°; and Number of Blades 5.

This study aims to determine the effect of plastic deformation percentage variations (0%, 25%, 50% and 75%) in SMAW (Shielded Metal Arc Welding) welding of AISI 1020 on the microstructure and mechanical properties of the material. Welding is carried out with a current of 80A and a voltage of 30 V. The results of macroscopic observations found that the greater the proportion of plastic deformation, the greater the width of the HAZ (Heat Affected Zone). The results of microstructural observations with an optical microscope show that the greater the proportion of plastic deformation, the finer the shape of the ferrite in the BM (base metal) region. On the other hand, in the FGHAZ (Fine Grain Heat Affected Zone) region, the ferrite shape becomes coarser as the proportion of plastic deformation increases. Meanwhile in the CGHAZ (Coarse Grain Heat Affected Zone) region, a ferrite phase is formed at grain boundaries with coarse pearlite for each variation of plastic deformation. The results of the hardness test show that the greater the proportion of plastic deformation, the greater the hardness value in the BM region. In the HAZ and WM regions, the greater the proportion of plastic deformation the lower the hardness value. The results of the tensile test show that the greater the proportion of plastic deformation, result in greater UTS (Ultimate Tensile Strength) and YS (Yield Strength) values.

Metal Inert Gas Welding (MIG) is an LSW welding method that uses CO2 as a protective gas. The MIG welding process is more widely applied to various welding positions and is more efficient and inexpensive. This welding process is suitable for construction. However, the MIG welding process requires a skilled welder because it requires continuous and stable control to prevent burn- back. The heat-affected zone (HAZ) is the area formed around the groove due to the heat input of the welding material. In the HAZ region, there is a change in the microstructure, which causes changes in material properties. The welding process was carried out at speeds of 2.75, 3.49, 2.67 and 3.41 mm/s with pressure variations of 10 and 15 bar. Changes in material properties occur due to welding speed which indicates the amount of Heat Input (HI) received. The higher welding speed causes a decrease in the HAZ area, which indicates a more ductile material

To maximize turbine performance, it is crucial to broaden a deeper comprehension of the flow structure at tip region of the rotor blade and its consequence. The purpose of this study is to examine the impact of tip clearance flow in a low-pressure steam turbine. The research focused on the final stage of the low-pressure steam turbine blade of a typical steam power plant operating at 3000 rpm (50 Hz). Steady-state compressible numerical simulation and blade stress analysis was performed to analyze the flow characteristic and blade stress level on the last stage blade under three operating load conditions. Two variations of rotor blades are adopted. The results found that the torque in both models increased with an increase in loads resulting in increasing turbine output. However, the torque generated by tip clearance model is smaller than torque in the model without tip clearance. It can be implied that the turbine performance is reduced as a result of the presence of tip clearance flow corresponding to tip leakage loss. The blade stress analysis shows that the stress level exceeds on rotor blade in model tip clearance is higher compared to model no-tip clearance under 100% and 120% load.

This study conducted an experiment to investigate the metallurgical and mechanical properties of joints made through rotary friction welding (RFW) using AA6061 aluminum alloy rods. The examination of the microstructures in the RFW joints was carried out by employing optical microscopy, along with observing the weld macrostructure using a low magnification microscopy to examine the flow behavior during the RFW process. Subsequently, the characterizations of RFW joints were conducted using Vickers microhardness measurements, tensile tests and fatigue tests using a rotating bending machine in combination with fractographic study. It was discovered that the higher welding time led to improved strength of the AA6061 weld joints but accompanied by the formation of more flashes and higher burn-off length. In contrast, at a low welding time, typically 5 s, the RFW process was inadequate to produce the friction heat required to make sound weld joint hence resulting in low strength. It appeared that the most satisfactory weld joint was achieved at 10 s welding time as indicated by its high strength, around 223.2 MPa with less flash was produced compared to the weld at the welding time of 15 s. This particular RFW joint had the fatigue strength lower than that of AA6061 base metal and the fatigue crack origin was located at the HAZ of AA6061 owing to softening during the welding process.

Traditional hand-laid fiberglass reinforced plastic (FRP) 10 GT fishing boats often fall short of Indonesian Classification Bureau (BKI) standards, lacking the required tensile strength (98 MPa), modulus elasticity (6.86 GPa), and bending strength (150 MPa) with MOE 6.86 GPa. The extensive production of ships in Indonesia has led to increased demand for fiberglass, contributing to carbon emissions and air pollution, exacerbating global warming. This study explores the feasibility of environmentally friendly alternatives by partially replacing the fiberglass layer with a thin bamboo woven twill strip (5mm wide). Tensile and bending tests were conducted on composite specimens combining fiberglass and bamboo to assess compliance with BKI sailing standards. Tensile tests followed the American Standard Testing and Material (ASTM) D638, while bending tests adhered to ASTM D790 standards. Alkalized bamboo strips exhibited tensile strengths of 111.718 MPa (without alkalization) and 221.692 MPa (with alkalization). Hand lay-up FRP testing, with and without a press, indicated superior results for specimens with a press (tensile: 221.856 MPa, bending: 229.856 MPa) compared to those without (tensile: 112.227 MPa, bending: 228.476 MPa). Further experiments involved four-layer hybrid composites, replacing one fiberglass layer with woven bamboo in WR 800 and CSM 450 sections. The WR 800 replacement yielded tensile strengths of 106.316 MPa and 166.234 MPa, while the CSM 450 replacement resulted in strengths of 118.806 MPa and 62.451 MPa. The study successfully identified a hybrid composite composition, incorporating woven bamboo (WR800), that meets BKI standards for 10GT vessels in FRP composites with a press.

Rice bran contains various bioactive compounds, including γ-oryzanol, which can reduce hypercholesterolemia. However, the reactivity of γ-oryzanol in the environment results in the need for encapsulation to maximize the use of bioactive compounds. Many encapsulation processes have been developed using wall material from many resources. Rice bran, which also contains rice bran protein (RBP), has hypoallergenic properties, good foaming stability, and can be used as a wall material. Therefore, this work focused on enhancing protein extraction from defatted rice bran (DRB) by microwave-assisted extraction (MAE) to produce RBP suitable for encapsulating γ-oryzanol. RBP obtained by conventional alkaline extraction (CAE) revealed that the highest yield of RBP of 7.88% was obtained at T 60 °C, t 60 min., and pH 11. This operation condition was then used to optimize the extraction of RBP-MAE using power and time variables. The RBP-MAE is as high as 14.16%, almost double compared to RBP-CAE at power 100W, t 25 min., and pH 11. The solubility, foaming, and zeta potential of RBP revealed properties that make it a suitable wall material for γ- oryzanol encapsulation.

This paper presents a numerical modeling approach using a 3D nonlinear finite element package to investigate the stress–strain behavior and the impact of polypropylene fibers on a notched beam. Polypropylene fibers have shown promising results in improving the mechanical properties of concrete. In this study, a notched beam with a 1.25% volume fraction of polypropylene fibers was subjected to three-point bending conditions to evaluate the behavior of polypropylene fiber-reinforced concrete. The in-house 3D nonlinear finite element analysis package, 3D-NLFEA, simulated the three-point bending conditions using a plasticity-fracture concrete model. This research aims to demonstrate the effects of adding polypropylene fibers on the mechanical properties of the notched beam, comparing it with plain concrete. Additionally, this analysis provides insights into deformation, peak load, crack pattern, post-peak behavior, and stress–strain characteristics of polypropylene fiber-reinforced concrete compared to plain concrete.

A numerical study is carried out on downward push–pull air curtain for creating a personalized ventilated zone and preventing droplets exhaled by coughing process from entering the vicinity of a standing healthy worker in shop- floor setting. The healthy worker inside the air curtain and the cough emitter out- side is modelled using ergonomically proportioned mannequins considered to be a typical Asian male. The parameter study is conducted at constant pull velocity of 8 m/s, while the push velocity is varied such that ratios of pull to push veloci- ties are 1–8. Under the current configuration, the curtain shows concave-curtain and under-suction regime. The current configuration cannot completely shield the healthy worker from the droplets as some droplets could still penetrates the curtain, riding the entrainment between cough jet and the pull flow. Smallest number of droplets is found inside the curtain when the veolcity ratio is between 5 and 6.

This paper presents an advanced analysis of the fracture behavior in steel fiber-reinforced concrete using an in-house 3D nonlinear finite element analysis (3D-NLFEA). The 50 MPa concrete strength, specially designed for slab-track structures, is strengthened with hooked-end DRAMIX 3D 65/35 fibers. The purpose was to gain additional tensile strength and improved post-peak behavior, including enhanced fracture tensile energy and toughness of the steel fiber reinforced concrete (SFRC) compared to plain concrete. This study uses an experimental and numerical simulation of the noted SFRC beam with 2.0% fiber content. The load in the experimental test is applied as a static load and is controlled using displacement control. The numerical simulation uses an in-house 3DNLFEA package utilizing the multi-surface plasticity-fracture model. The test result shows that the tensile strength and fracture energy increased significantly. The developed numerical model was able to capture accurately the peak load and the post-peak softening behavior of the notched SFRC beam.

Electrospinning has many advantages in fabricating nanofibers in terms of being relatively inexpensive and quite simple. Indeed, several important parameters need to be considered when utilizing the machine. In order to produce nanofibers with good textural quality, one way to improve the properties is by varying the surfactant concentration. A composition of 0, 3, 7, and 10 wt. % Triton X was mixed with 8 wt.% Polyvinyl alcohol (PVA) in 60 ml distilled water as the precursor solution. A flow rate of 12 ml/h, the distance between the needle tip and the collector of 15 cm, the rpm of the collector of 200 rpm, and a voltage of 15 kV were set on the machine. The precursors were then fabricated using an in-house electrospinning machine. Characterization of nanofibers was done using Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and Fourier Transform Infra-Red (FTIR). Uniform nanofibers with the smallest crystallite size were successfully produced by a 7 wt.% of Triton X. FTIR spectra showed that the resulting nanofiber was pure and uncontaminated with impurities. A semi-crystalline PVA structure was observed in the XRD pattern. Indeed, the addition of Triton X contributes to reducing the formation of the beads and increasing the homogeneity of precursors.

This paper presents a modeling and control approach using feedback linearization and LQR control for a reaction wheel pendulum system. First, the equations of motion for the reaction wheel pendulum system are derived. Then, feedback linearization is employed to linearize the nonlinear system dynamics. This technique transforms the original system into a linear system by canceling out the nonlinearities using feedback. The control design utilizes the linearized model obtained through feedback linearization in conjunction with the LQR control strategy. Simulation results demonstrate the effectiveness of the combined feedback linearization and LQR control approach for stabilizing the reaction wheel pendulum system.

The thermoacoustic engine is a green technology that can harness solar and waste energy to produce electricity in combination with a linear alternator and can be used as a heat pump. This type of engine is particularly appealing because it has a simple structure and contains no mechanical moving parts, consisting only of a stack sandwiched between heat exchangers within a resonator. When the temperature gradient on both sides of the stack reaches the critical temperature (onset temperature), the working gas oscillates spontaneously. Due to viscous loss in the system, a high onset temperature is typically required to induce gas oscillation in a thermoacoustic engine. To address this challenge, a method has been developed to reduce the onset temperature by increasing the number of unit stages comprised of stack and heat exchangers, which has enabled the engine to utilize low-grade thermal sources. However, this method has only been applied to traveling wave thermoacoustic engines, and the standing wave one which provided a more compact and straightforward structure has not yet been explored. This study aims to know the influence of the number of unit stages in a standing wave thermoacoustic engine that can impact both the onset temperature and its acoustic field. The onset temperature is predicted by utilizing a fundamental equation of hydrodynamics and then using DeltaEC software to investigate the acoustic field throughout the engine. The result showed that an appropriate number of unit stages in the standing wave thermoacoustic engine need to be considered in order to get the optimum engine.

This paper presents a nonlinear finite element simulation of the top slab-track layer railway designed for high-speed train systems. The study investigates the top slab-track layer previously designed using a conventional reinforced concrete (RC) structure with the new material design based on fiber-reinforced concrete (FRC). This study is the pilot project on using advanced material technology for the slab-track structure. The two fibers that would be used to construct the FRC are the hooked-end steel fiber DRAMIX 3D 65/35 and polypropylene fiber. The volumetric content of both fibers is 2.0%. The basic concrete strength is 50 MPa. In this paper, only one panel of slab-track is being investigated. The panel has a width of 600 mm, a width of 2500 mm, and a thickness of 200 mm. The panel is tested as a simply supported beam with an inverted position to mimic the restraint imposed by the wheel train. The simulation uses an in-house 3DNLFEA package with a multi-surface plasticity model suitable for modeling plain and fiber-reinforced concrete. The simulation found that using fibers can improve the peak load-carrying capacity and enhance the post-peak softening behavior of the slab-track structures.

Shape memory alloys can revert to their original form when deformed and heated beyond their transformation temperature, known as the shape memory effect. This study explored the impact of temperature and artificial aging on Cu0,83Al0,14Zn0,03 alloy created via powder metallurgy. The alloy, comprising Cu, Al, and Zn powders, underwent a 3-h ball milling process, forming green density samples of 20 mm diameter and 5 mm thickness through 10 tons of pressure for 5 min. Subsequent steps included sintering at 750°C for 1 h, fast immersion in brine media, and artificial aging at 250°C and 300°C. Aging maintained a fixed 30- minute time, with holding times of 45 and 90 min at a constant 250 ℃. Results showed a consistent reduction in crystal size (0.606 nm to 0.533 nm), an increase in dislocation density (4.815–6.056 line/mm2), and a significant rise in micro-lattice strain (0.196–0.214). Temperature and aging impacted mechanical properties, reducing hardness from 63 to 47 HB, tensile strength from 223 to 166 MPa, and yielding a diminishing yield strength. These findings underscore the intricate relationship between pro- cessing parameters, microstructure changes, and the mechanical behavior of shape memory alloys.

Riding comfort is the minimum vibration transferred by the road surface to a passenger, where it is characterized by maximum sprung mass acceleration. International standards determine riding comfort, specifically ISO 2631. This research utilizes a genetic algorithm to obtain optimal stiffness and damping coefficients for the vehicle suspension system. The system modeling is simulated using MATLAB software. Based on the genetic algorithm optimization performed, the optimal stiffness and damping coefficients obtained for the system are 203,800 N/s and 12,771 Ns/m for the front suspension stiffness and damping coefficient, respectively. The rear suspension stiffness and damping coefficient are 310,750 N/s and 10,702 Ns/m, respectively. With the optimized parameters, the dynamic responses of acceleration and displacement in vertical and pitch motions yield more comfortable results. The conclusions are drawn based on the root mean square (RMS) acceleration value for drivers who meet ISO 2631 comfort standards. The driver's system operates comfortably without complaints at low speeds, with only minor complaints at high rates. With the optimized suspension, the driver can sustain over 16 h of operation, whether subjected to sinusoidal road. The optimized parameters result in an improved transient vehicle response, characterized by reduced impact forces and quicker attainment of settling time.

In this article, a novel strategy to recommend the cutting speed in lathe machines is introduced. The recommendation was obtained through a transverse cutting in a CNC lathe machine with the G97 feature. However, as a preliminary study, this study was developed through a simulation approach in Matlab/Simulink to introduce an insight that an unwanted behavior in transverse cutting with the G97 feature can give a novel way to obtain recommended cutting speed value for the machining process. The simulation was built with one degree of freedom of the mechanical system (m, c, and k) mathematical model. In addition, since this study involves the speed change effect in the turning process, thus the velocity-dependent force coefficient was also included in that model. The simulations were processed with three different spindle speed settings and constant feed rate and cutting depth values. Moreover, the simulation also implicated different cutting force coefficients to analyze the recommended cutting speed in different materials to gain deeper insight. The results showed that the cutting speed can be recommended by considering the unwanted behavior of cutting force in CNC lathe machine transverse cutting. This approach's recommended cutting speed of AISI 1045 is 120–565 m/min. However, that range's maximum limit will also depend on the maximum CNC spindle speed ability to rotate.

This article shown the performance evaluation of AISI 4340 using the hot-turning method. AISI 4340 is a medium carbon steel known for its impact resistance and is commonly used in gear components of airplane systems, crankshafts and connecting rods. This research focuses on developing mathematical models using Artificial Neural Networks (ANN) to analyze the relationship between dependent and independent variables. The ANN is suitable for nonlinear machining operations with high accuracy and without a predetermined model. Modelling techniques, specifically ANN, are suggested to improved machining effectiveness and reduce production time and costs. This article explains the architecture and function of ANN, describing neurons, weights, and activation functions. This research methodology includes data pre-processing, network training using Back Propagation (BP) algorithm, and selecting activation functions. The Levenberg–Marquardt algorithm is used for training, and the hyperbolic tangent sigmoid transfer function is utilized as the activation function. The results show that a 4–17-1 network structure provides the closest prediction to experimental data for surface roughness, with an MSE of 0.004393106, and a prediction error of 3.79522%. The result demonstrates usefulness of ANN in predicting the machining quality.

This research aims to predict and create a model of cutting force as a response to multiple parameters in the face milling process of JIS SKD 11 tool steel material. The face milling parameters are coolant flow rate (Q), cutting speed (Vc), feeding speed (Vf), and axial depth of cut (Aa). The flow rate (Q) for cryogenic cooling has two levels. Cutting speed (Vc), feeding speed (Vf), and axial depth of cut (Aa) each have three levels. Using the Taguchi method, it has an L18 mixed-orthogonal array as the experiment design. Using ANOVA, the parameters are qualified to only those significant toward cutting force. The prediction uses Sugeno type-1 and Mamdani type-1 fuzzy inference systems (FIS). The tuning of FIS is conducted using genetic algorithm. The tuned parameters were rules-only and rules-and-output. The membership functions are set to be Gaussian The results are shown in surface plots and root mean square error (RMSE). The result shows errors are less than 5%, which tells the cutting force has been successfully predicted.

This study investigated the prediction of end milling parameters on surface roughness during the symmetrical cryogenic end milling process of AISI D2 tool steel. The varied milling parameters are the flow rate of cryogenic cooling, cutting speed, feed rate, and axial depth of cut. The experimental design selected is an L18 orthogonal array based on the Taguchi method. Experiments were randomized entirely and repeated twice. The prediction methods applied were fuzzy inference system (FIS) Mamdani type 1 and Sugeno type 1, utilizing the Gaussian membership function. A genetic algorithm was selected to tune FIS. The smallest value of RMSE is applied to determine the best FIS for prediction. The result showed that FIS Sugeno type 1 with rules and output tuned had the smallest RMSE. The error between the predicted and measured values was only 0.99%.

Boring bars with a large length-to-diameter (L/D) ratio in the machining process can cause excessive vibration or chatter, which reduces product quality. Dynamic vibration absorber (DVA) is a vibration reduction system that can reduce the chatter effect. In this study, DVA has the shape of a cone placed inside a boring bar, which consists of a mass of absorber made of brass covered with rubber. The rubber is varied, namely natural rubber and neoprene rubber. The simulation is carried out with various cutting parameters, including spindle speed, feed rate, and depth of cut. Based on the simulations, the DVA cone's shape allows it to reduce vibrations in all directions and produce the same reduction values on each axis. Customized boring bar L/D 9 with DVA natural rubber and cutting parameter 2 is the variation with the highest vibration response reduction value, namely 88.50% in the x-axis direction, 83.89% in the y-axis, and 88.52% in the z-axis. Customized boring bar L/D 7 is a geometry variation with the best operation because it can reduce vibration in most variations of cutting parameters compared to other variations of boring bars, namely 23 out of 27 cutting parameters.

Failure control of pipelines due to internal corrosion can be realized by the addition of chemical inhibitors. The environtmentally benign nature of organic-based inhibitors, known as “green inhibitor” or “bioinhibitor,” makes them promising for more development. By producing a barrier that prevents metal from contact with the environment, organic molecules adsorbed on metal surfaces can reduce the corrosion rate. This study aimed at analyzing the effect of Bajakah Tampala (Spatholobus littoralis Hassk) extract added in a corrosive media of 3.5% NaCl solution. In this work, the test material used was carbon steel API 5L Grade B in 3.5% NaCl solution media with concentration variations of inhibitor of 0, 250, 500, and 750 ppm Bajakah Tampala extract. The extraction process involved maceration in a 96% alcohol solvent, followed by concentrating in a rotary evaporator. Potentiodynamic polarization and immersion tests were used to measuring the corrosion rate. The phase of rust was determined by XRD analysis. The findings of this study pointed out that the efficiency of Bajakah Tampala extract that can be obtained was 68% at a concentration of 750 ppm.

This failure analysis investigates tube failures in waterwall components of boilers, crucial for converting water into superheated steam. The study aims to distinguish primary leaks from secondary damage mechanisms, offering insights for power plant OEM safety references. Utilizing visual inspection and validated data collection methods, macrography analysis reveals wall thinning from steam erosion, reducing thickness to a critical 0.085 mm, far below the required 2.8 mm. SEM testing displays dimple rupture patterns, with metallography and hardness tests indicating no microstructural degradation. Chemical composition aligns with ASTM A210 Grade A1. Conclusively, the analysis attributes tube failures to steam erosion, classifying it as a secondary damage mechanism. The results guide the development of mitigation strategies, emphasizing immediate shutdown actions to ensure boiler safety and efficiency. This comprehensive study aids in preventing future tube failures, contributing to the reliability of boiler operations in power plants.

One of a city car’s most crucial components, the chassis, has to be built sturdy enough to support the weight of the whole vehicle. The purpose of the chassis is to prevent the vehicle from bending or deforming while in operation. The purpose of this project is to develop and test a two-passenger city car’s chassis. The stress on the chassis is tested in this research utilizing a development approach that makes use of software based on finite elements. The von Mises stress data are examined to ascertain the strength of the chassis. Two tests with different loads—the focused load and the dispersed load—are used in chassis loading analysis. The simulation’s findings demonstrate how effectively the city car’s chassis can support the weight. The maximum stress resulting from the focused load operating on the city car’s chassis is 29.97 MPa, according to the findings of the strength study conducted on the chassis. However, the dispersed load on the chassis results in a maximum stress of 108.10 MPa.

The surface grinding is a machining process primarily used to achieve a very smooth surface. In addition to the depth of cut, the cross-feed parameter is very influential on the vibration and has a direct impact on its roughness. High cross-feed influences productivity so that machining time is shorter, but results in low surface quality and vice versa. In this study studied the effect of cross feed on vibration and its consequences on surface roughness. Thus, it is expected that only by monitoring vibrations in real time can control the surface roughness produced by this surface grinding process. The experiment shows that the increase in cross-feed from 5.3 to 11.7 mm/stroke, for the A46QV type grinding wheel, gives an increase in vibration amplitude from 6.74 to 18.75 g rms and this results in an increase in surface roughness from 0.52 to 1.47 μm. Whereas the A80LV, the finer type grinding wheel provides an increase in vibration amplitude from 5.09 to 18.28 g rms and this results in an increase in surface roughness from 0.36 to 1.42 μm.

Bearing preload has a major influence on frictional heat generation, whereas cooling fluid substantially influences the spindle system’s heat balance. Finite element modeling was utilized to investigate the effect of bearing preload on the thermal behavior of a machine tool spindle. Both bearing heat generation and cooling fluid were applied as boundary conditions of Finite Element Method (FEM) model. The FEM analysis includes steady state and transient thermal analysis at two different spindle speeds 3000 and 15,000 rpm. Based on the analysis’s findings, it can be seen that the bearing preload changes affect the heat generation and temperature. The difference in heat generation between the minimum and maximum preload values at rotational speeds of 3000 rpm and 15,000 rpm is 9.5 W and 47.4 W, respectively. When increasing the bearing preload from EL to H at low spindle rotation speeds of 3000 rpm, the temperature rise is roughly 0.56 °C. However, at high spindle rotation speeds of 15,000 rpm, the temperature rise could reach 2.75 °C.

Superheater drain tube is one of the components of Heat Recovery Steam Generator (HRSG). The tube experienced failure after twenty years of operation. The failure was noticed due to the finding of water drips during regular inspection. After removal of pipe insulation during operation, it was found that there was a steam leakage in the tube. The paper analyzes the failure of the superheater drain tube so that similar failure can be avoided. Field observation, visual inspection, XRD, chemical test and metallography were carried out in order to investigate the failure. Results of field observation and visual inspection reveal that the pipe experienced wall thinning originated from external side of the pipe. No anomalies or defects can be found in the internal wall of the pipe. Hence, it is determined that the tube leakage was caused by progressive external or outer wall thinning due to corrosion under insulation. The corrosion occurs due to reaction between tube external surface and water, forming corrosion product in the form of Fe3O4 and Fe2O3. The source of the water may originate from water moisture yielded from condensation of tube surface and water contained glass wool insulation. Hanging clamp improper installation may also act as water pathway from external environment into the glass wool.

The bottom slope in a supercritical boiler system interface with the waterwall and plays a crucial role in converting liquid phase to superheated steam. Its design must factor in material strength, fluid flow rate, temperature, and pressure. The purpose of this failure analysis is to discern the primary cause of tube failure and avert future occurrences. Data collection involves examining the boiler’s design operation and nondestructive inspections. The macrograph revealed wall thinning due to impact from large slagging falling from the superheater division panel. This led to abrasion of the outer tube. Scanning Electron Microscope (SEM) testing highlighted abrasion fracture patterns, alongside metallographic findings of microstructural degradation. Consistent hardness test results showed values of 200–210 HV near the failure site. The chemical composition aligns with ASTM A213 T12 material standards. This analysis identifies falling slag abrasion as the primary damage mechanism in bottom slope tubes. The findings can aid in formulating effective strategies to prevent tube failures, optimize slagging cleaning frequency, and enhance boiler operation safety and efficiency through shutdown procedures and preventive measures.

In the present work, mechanical properties and corrosion resistance of friction stir AZ31B-H24 magnesium alloy welded joints with variation in tool rotation speeds of 910, 1500 and 2280 rpm have been investigated. Friction stir welding (FSW) processes were performed using a tool having a triangular pin which moved along a joining line at a speed of 60 mm/min. After welding, various number of tests were carried out including macro- and microstructure observation, Vickers microhardness measurements, tensile tests and corrosion measurement in 3.5% solution using Tafel technique. Results showed that high strength of the FSW welded joint, typically 212.2 MPa was obtained at a tool rotation speed of 2280 rpm resulting in a welding efficiency of 86.3%. Similar to the results of tensile tests, it was found that the FSW joint with excellent corrosion resistance was produced at the tool rotation speed of 2280 rpm with the corrosion rate of 0.015 mm/year.

The pursuit of achieving the lightest possible structures without compromising safety and strength initially emerged in motorsports and has rapidly disseminated into the automotive industry. This advantageous trend has led many racing vehicles to adopt monocoque chassis constructed from carbon fiber sandwiches with honeycomb cores. A monocoque chassis embodies a singular structural unit wherein the body functions as a load-bearing element. This chassis supports the suspension, steering, drive, and other essential components and showcases exceptional strength. Despite these advantages, certain vehicle segments still require metals, as in some racing competitions like the DTM Racing Car in Germany. Considering this, because sandwich structures are weak under localized loads since the honeycomb compresses easily, reinforcement is introduced used on the connection zone of composite and metal material to spread the load to a larger area. This research will determine Tensile Pull-Out strength with an experimental method that refers to ECSS-E-HB-32-22A Space Engineering: Insert Design Handbook by the European Cooperation for Space Standardization (ECSS). This new reinforcement method will take the pull-out strength advantage of the insert method and the load spread benefit of the chamfer method. According to some studies, the potting mass will fill the space in sandwich structures, making the structure heavier. The new reinforcement method will remove the potting mass, replace it with carbon fiber layers, and add a metal insert. From this research, the new reinforcement method has an average Tensile Pull-Out strength of 8012.03 N, and the old reinforcement method has an average Tensile Pull-Out strength of 3620.35 N and 4897.54 N. From that result, the new reinforcement method has better Tensile Pull-Out strength than the old one.

Organic briquette could be made of coconut shell and palm tree shell. In the current case, 30% of the briquette feedstock were not properly milled, resulting defects. The identified defective modes were improper fineness or particle size. To address this issue, a study to modify and develop a crusher machine aiming to improve the grinding process and reduce waste material was initiated. The Ulrich-Eppinger method was selected as development framework to solve the development problem. This framework starts from concept development to product architectural and detailed design. The study utilized Altair EDEM simulation to simulate the grinding process. The results showed that the developed grinding machine successfully achieved the desired fineness for coconut shell particles with an average diameter of 0.384 mm. Similarly, the palm shell powder manufactured by this machine produced powder particles with an average diameter of 0.31 mm. These conditions were within the expected particle size of <0.40 mm and could be sieved using a 40 mesh screen.

Passive micro-mixers are indispensable components within microfluidic systems, and this research delves into the nuanced interplay of various design parameters on the mixing efficiency of a Koch fractal micro-mixer with rounding corners (RCSM). The study systematically examines cross-sectional shapes, inlet angles, obstacles, and 3D printing methods to unravel their collective impact. The Design of Experiment (DoE) methodology proves instrumental, allowing for the simultaneous exploration of these parameters. Computational Fluid Dynamics (CFD) simulations serve as the experimental platform, showcasing that the RCSM micro-mixer, characterized by a trapezoid cross-section and a 180° inlet angle, attains peak mixing efficiency (0.976) when devoid of obstacles and utilizing the SLA 3D printing method. Notably, the research underscores the preeminent influence of the 3D printing method on mixing efficiency, followed by the inlet angle, cross-sectional shape, and the presence of obstacles. This comprehensive exploration advances our understanding of passive micro-mixer dynamics, offering valuable insights for optimizing microfluidic systems in diverse applications, from medical diagnostics to chemical analyses.

This study examines the correlation between the tensile strength of ramie (Boehmeria Nivea) yarn at different gauge lengths under uniaxial static tensile loading. The stress–strain curves for each gauge length were inconsistent due to the non-uniformity of the ramie yarn diameter. Strain hardening and multiple load drops were seen on the stress–strain curves, which is beneficial for structural applications where performance and safety are a significant concern. When the gauge length increases, the tensile strength decreases due to more defects, which act as stress concentration on the fibres. This behaviour also confirms that the size effect plays a role in ramie fibres. The large variability of more than 10% in the ramie fibres should be taken as a precaution when designing structural parts made of this material.

In the field of medicine, simulating human bone is crucial as the actual human bone was difficult to obtain. Orthopedic doctors use artificial bone models extensively for surgical practice, especially bone fracture repairs. Human artificial bones made from polyurethane foam offer a viable alternative, closely mimicking natural human bone properties. Polyol and isocyanate are combined with additives like a blowing agent (distilled water), catalysts, and surfactants to modify their physical and mechanical properties to create this rigid polyurethane foam (RPUF). Due to environmental concerns, there is growing interest in renewable-based polyol for polyurethane foam production, but the study on additive impacts with renewable-based polyol is limited. This study investigates the effects of specific additives (distilled water as a blowing agent, amine as catalyst, and silicon glycol as surfactant) on rigid polyurethane foam (RPUF) made with renewable-based rapeseed oil polyol. Various parameters, including amounts of distilled water of 0.2, 0.6, and 1.0 g per hundred grams of polyol (pphp), catalyst of 0.2, 0.4, and 0.6 pphp, and surfactant of 2, 4, and 10 pphp had been tested. The RPUF samples were then tested following ASTM F-1839 standards, evaluating macrography, density, void content, compressive strength, compressive modulus, and SEM. The research shows that higher distilled water content in RPUF reduces its physical and mechanical characteristics as larger cell sizes and thinner foam cell walls are formed. In contrast, higher catalyst concentrations improve RPUF’s physical and mechanical properties by expediting gelling and blowing reactions, forming smaller, thicker foam cell walls. Similarly, higher surfactant content improves RPUF’s properties by reducing surface tension, enhancing polyol dissolution and homogeneity, resulting in more foam cells during the reaction and preventing cell growth. The study reveals that with addition of catalyst provides the highest effect on the properties of RPUF.

More than 30 million people have been affected globally by the coronavirus disease 2019 (COVID-19), which has resulted in over 900,000 deaths (Lumlertgul et al. in Kidney International Reports. 6:196–218, 2019). Many healthcare systems have faced significant challenges in treating a large number of patients due to inadequate resources. These challenges are shared by Indonesia, where many active medicinal components are still imported. According to Basic Health Research (Riskesdas) data from 2013 to 2018, the prevalence of chronic renal disease in the Indonesian population was 2% in 2013 and climbed to 3.8% in 2018. As a result, after heart illness, treatment of kidney disease is the second-largest source of funding from the Indonesian National Health Insurance (Prodjosudjadi and Suhardjono in Ethn Dis 19:33–36, 2009; Liu et al. in Int J Environ Res Public Health 18:9215, 2021). Hemodialysis (HD) is one of the therapies used to help kidney failure patients maintain an ideal quality of life, and it accounts for up to 82% of dialysis services performed in health institutions. There are impediments to getting health treatments and a risk of financial difficulty due to nonmedical costs related to the restricted HD services. Chronic diseases, in addition to kidney problems, significantly raise the likelihood of incurring catastrophic health-care costs. As a result, indigenous production of dialysis solutions is required. Acid-concentrated, bicarbonate-concentrated, and high-purity water are combined to make the dialysis solution. Conductivity and pH measurements were performed on the dialysis solution. The results revealed that the dialysis solution products, including acid-concentrated and bicarbonate-concentrated, meet international standards using domestic materials.

The study of structural strength on aircraft wings is important because it involves flight safety. The Spar is the main component of an airplane wing which transmits most of the lift to the fuselage, so this research is focused on the strength of the spar. The research conducted is a study of the wing spar of Medium Altitude Long Endurance Unmanned Aircraft (MALE UAV) with a total mass of 1,300 kg, with a wingspan that is 16 m long, and must be able to withstand loads with a load factor of 4G. Alternative uses of material dimensions to make them lighter and stronger so that aircraft performance can be improved. The analysis was carried out by estimating the distribution of wing lifts using the Schrenk Approximation method. Mathematical calculations were carried out to determine the mechanical strength. The effect of the taper ratio not only applies to lift distribution, but also to its strength, and the taper ratio ≤0.4 is the value that meets the strengths in this study.

Aluminum 6061 is commonly used for the anodizing process. Anodizing is a coating method by forming an oxide layer on the metal surface which aims to protect and decorate. This research process uses aluminum 6061 as an anode and a Pb platea cathode, with electrolyte solution H2SO4 20%. Variations were made on the anodizing temperature (10 °C, room ±30 °C, and 50 °C) and variations on anodizing time (10, 15, 20, 25, and 30 min). The tests carried out were the Scanning Electron Microscope (SEM) to determine the thickness of the coating and the Megger test to determine the resistance of the material. The results of the research on the best and optimal coating thickness at the anodizing temperature of 10 °C were 3,004 µm with the anodizing time of 30 min, at room temperature ±30 °C with the best and optimal coating thickness of 12.2 µm with the anodizing time of 20 min, and at 50 °C the best and optimal coating thickness was 14.44 µm with the anodizing time of 20 min. So that the higher the anodizing temperature and the longer the anodizing time will form a higher layer thickness value. However, if it has exceeded the optimal point, the layer thickness will decrease. This research, it is hoped that it can support SMEs’ anodizing service providers in developing optimal anodizing temperature and time variations to improve the quality of anodizing products.

A pressure vessel that functions to store liquid or gas which is often used in the oil and gas industry and has a pressure difference on the inside from the outside. Pressure vessels have several important components. These components are interconnected using a welding process. The welding process is carried out by many variables that determine the result of the welding, one of which is the strong current. The welding results are not spared by the existence of errors in the welding process. These errors are in the form of welding defects which can interfere with the quality or quality of the welding results. To be able to detect a defect and to be able to determine the quality from the welding results, a non-destructive testing process is carried out. The non-destructive test used in my final project is using the magnetic test method, penetrant test, and radiography test. this can find out the type of defects that occur in the pressure vessel and can determine the best type of Non-Destructive Test method for detecting a defect in the welding results carried out in the pressure vessel manufacturing process. welding defects that occur. In addition, additional tests will be carried out in the form of corrosion rate testing using the weight loss method with variations in welding currents which will later obtain data on the relationship between strong currents and the corrosion rate that occurs.

An assessment of the condition of the boiler tube is necessary to determine its fit for service, especially for an old boiler. Most of the time, the challenge is a limited record of the boiler inspection and design and commissioning data. This tube inspection and condition assessment needs to be conducted as part of the remnant life assessment. In the present work, inspections and remaining life assessments of tubes in the boiler in the petrochemical plant are reported. The tube inspection comprises a thickness survey, in situ metallography, and hardness measurement. The results show that all those data is correlated and can be used to estimate the boiler’s remaining life, which can also be used as a maintenance baseline for further operation. The present investigation is a field experience and might be used as a guideline for performing RLA for old boilers for fit-to-service or regulation needs.

Stainless steels, including ferritic-martensitic and precipitation-hardening stainless steel, find extensive utilization in low-pressure steam turbine blades for steam-powered energy generation plants. The failure of these blades often stems from fatigue originating in the pitting region due to corrosion attack, highlighting the importance of investigating the susceptibility of such incidents. This paper presents an investigation of pitting corrosion in stainless steel 410 and 17Cr4Ni alloy steel using electrochemical methods to probe the pitting behavior and assess the susceptibility of stainless steel to localized corrosion. The experimental setup involved exposing specimens to 1000 ppm sodium chloride (NaCl) solution and artificial seawater comprising three wt% NaCl and monitoring their electrochemical responses with linear polarization and cyclic voltammetry. The outcomes demonstrate that 17Cr4Ni exhibits superior corrosion resistance and passivation performances in three wt% NaCl content. However, it is noteworthy that the outcomes are comparably consistent when the specimens are exposed to a 1000 ppm NaCl environment.

3D printing technology is one of the additive manufacturing processes that is starting to be widely used in Indonesia today. This technology’s ability to create various forms of design into three-dimensional visuals makes it one of the most popular technologies in the world of engineering. The quality produced by 3D printing depends on the type of filament and the careful selection of process variables. In recent years, a lot of research has been carried out in an effort to explore various ways to improve the quality of printouts from 3D printer machines with various variations of parameter optimization and experimental design concepts. This research aims to improve the quality of extrusion-type 3D printer prints with FDM (fused deposition modeling) technology for the Creality Ender 3 using PLA+ filaments, which have slightly better strength than standard PLA filaments, which are widely used in general. By designing optimum process parameter settings using the Taguchi method with three process parameter factors, which include print temperature, layer thickness, and print speed, which are also adjusted to the characteristics of PLA+ filaments, optimum settings were obtained with printing temperature of 230 °C, layer thickness of 0.20 mm, and print speed of 100 mm/s.

The airflow around a cylindrical object holds significant engineering applications and remains a prominent topic in aerodynamics research. The circular cylinder experiences substantial dynamic drags due to flow separation. The Ansys Fluent® was employed to analyze the aerodynamic forces on the main cylinder and its interaction within a 2D unsteady flow. The main cylinder investigation has a D = 60 mm diameter tandem with a d/D = 0.125 cylinder of the D-65° type. The distance between the central points of both cylinders was s/D = 1.375. The Reynolds number was Re = 5.3 × 104 with a U∞ = 14 m/s velocity. The simulation employed the transition k-kl-ω (3 eqn) turbulence model. The study revealed that tandem cylinders exhibit superior aerodynamic performance by comparing measurement parameters for single and tandem cylinders. One key parameter investigated was the coefficient of pressure (CP), which indicates the extent of separation delay around the central cylinder. The result presented within the lift coefficient (CL) decreased by 15%, the coefficient of drag (CD) reduced by 46.95%, and the pressure and wind speed contours indicated delayed separation and diminished pressure drag.