Design and Modeling of Mechanical Systems - IV

With the new technologies of the product design, the assembly automation lines has expatriated to a new assembly strategy characterized by an assembly modularization. This strategy consists, in a first time, in preparing subassemblies on secondary lines and then assembled with each other on the main line in a second time. The choice has been made to automate certain sections of the main line and to leave the subassembly lines in a manual way. The aim of this work is to identify the subassemblies of a mechanical product from its CAD model in order to predict secondary’s assembly lines. For better discussing and explaining all the steps of the proposed approach a CAD assembly of an industrial complex product is presented in all sections of this paper.

Tolerance allocation approaches serve as effective tools for design engineers to reduce the total manufacturing cost of mechanisms as well as to improve the product quality. In every mechanical design, the major task of design engineer is to allocate tolerances and clearances to the studied dimensions and joints, respectively, in a mechanism assembly. This paper presents an optimum tolerance allocation tool, based on manufacturing difficulty quantification using tools for the study and analysis of reliability of the design or the process, as the Failure Mode, Effects and Criticality Analysis (FMECA) and Ishikawa diagram. The proposed method is performed to produce, economically and accurately, allocated tolerances according to difficulty requirements. For this, an integrated CAD model is developed using Graphical User Interface (GUI) in MATLAB to expose diverse tolerance allocation approaches that respect the functional and manufacturing requirement. Many examples can be executed using the established GUI in order to highlight the advantages of the proposed approach.

The consideration of manufacturing defects in CAD tools is an important goal of industrials. Several studies have been proposed to take into account the geometrical and dimensional tolerances on the CAD modeler. However, the assumption of the rigid body is used and the deformations of non-rigid parts are neglected. In this context, the aim of this paper is to present a new Computer Aided Tolerancing (CAT) tool for cylindrical parts assemblies by taking into account both of geometrical and dimensional defects as well as deformations of components already generated during the system operation. The worst case tolerancing and the Small Displacements Torsor (SDT) are applied to model parts with dimensional and geometrical tolerances. The deformations of non-rigid cylindrical components are determined basing on the Finite Elements (FE) simulation. The realistic assembly is obtained by the update of mating constraints between couples of Rigid (R) and Non-Rigid (NR) realistic parts.

SPC (Statistical Process Control) is widely used to monitor processes. However, recent developments in Industry 4.0 and improvements of machine tools question the relevance of SPC. Using SPC in conjunction with EPC (Engineering Process Control) can partly improve the performance of processes. In this article, we define a new meaning of APC (Automated Process Control) which is based on three main innovations: the use of machine learning to control processes more accurately, the simultaneous consideration of all available characteristics in multidimensional processes and finally the dissociation between conformity and control for these characteristics.

The integration of environmental aspects in the design process is getting more and more covered by the scientific research. Owing to the issued regulations, industries tend to reduce their environmental impacts (EIs) while keeping a minimal manufacturing cost. The process plan operations order has an influence on the EIs and cost of a product. In this paper, we propose a new based scenarios methodology by using feature technology (FT) which allows the non-environmental expert designer to choose the most optimal manufacturing scenario with the best compromise EIs/Cost. First, we present an overview of works using the FT in CAD phase to reduce EIs and cost of a manufacturing process. Secondly, we propose a new methodology based on both FT and scenarisation which helps inexperienced eco-designers. Finally, a case study is considered to validate the proposed approach.

Transport and road traffic in particular are highly emitting noise pollution. These nuisances are considered one of the first threats to the quality of life and health. Indeed, noise pollution will continue to increase in magnitude and severity as a result of population growth, urbanization and growth associated with automobile use. In this paper, we propose an experimental study of vehicle noise based on measurement noise in three different sites. The main goal of this study is to determine the influence of different parameters, related to traffic and vehicle characteristics, in noise pollution emitted by vehicles. The experimental procedure was applied in three different sites used in order to integrate the influence of the infrastructure in noise comportment of vehicles. Results demonstrate that vehicle characteristics, traffic flow and infrastructure have an important influence in noise level of road traffic.

To minimize the number of iterations and correction returns while designing a system, sharing crucial parameters and data between different actors is needed. Since mechatronic systems are considered complex because of their multi-disciplines, their design requires collaborative work to ensure the sharing of parameters between contributors from different domains. This paper proposes a new methodology based on the collaborative design to choose the architecture of a mechatronic system. This methodology is structured around three main phases: the pre-collaboration phase, the collaboration phase and the post-collaboration phase. The proposed methodology has been validated by applying it on a mechatronic system called Electronic Throttle Body (ETB). In order to share the different established activities and capitalize knowledge, KARREN (Knowledge Acquisition and reuse for Robust Engineering) a collaborative tool from DPS (Digital Product Simulation) a French company, is used in this project to help us to choose the appropriate architecture of the Electronic Throttle Body.

In the textile manufacturing, development of sewing mechanisms with optimal performances is very significant. Obviously, the quality of sewing, decrease the sewing machine vibration and the optimal mechanical advantage are greatly dependent on the design criteria of the sewing mechanism. Therefore, this paper presents a multi-objective design optimization of a sewing machines. The needle jerk, the coupler tracking error and the transmission angle index are minimized simultaneously. The aim is to reduce the sewing machine vibration, guarantee a proper stitch formation and ensure the most effective transmission of motion, respectively. The multi-objective colonial competitive algorithm (MOCCA) is used to perform the design optimization. The obtained results confirm improvement of the required design criteria of the sewing mechanism in this study. It is also concluded that the optimized mechanism has 35% less needle Jerk and 20% reduction in term of the transmission angle index (TA) than the one for the Juki machine.

This paper examined the effectiveness of the inline re-design strategy used to mitigate the cavitating flow into an existing steel piping system. This strategy is based on substituting a short-section of the transient sensitive region of the existing main pipe by another one made of (HDPE) or (LDPE) plastic material. The (1−D) pressurized pipe flow model based on the Ramos formulation was used to describe the flow behavior, along with the fixed grid Method of Characteristics being used for numerical computations. From the case studied, it was shown that such a technique could mitigate the undesirable cavitating flow onset. Besides, this strategy allowed positive-surge magnitude attenuation. It was also found that pressure rise or drop attenuation was slightly more important for the case using an (LDPE) inline plastic short-section than that using an (HDPE) one. Furthermore, results evidenced that other factors influencing the surge attenuation rate were related to the short-section dimensions.

This paper explored the effectiveness of the inline technique-based re-design strategy in terms of pressure rise and drop attenuation and wave oscillation period spreading. Basically, this technique consists in replacing an inline short-section of the sensitive zone of the existing steel piping system by another one made of plastic pipe-wall material. Firstly, the 1-D unconventional water-hammer model combined with the Kelvin-Voigt and the Vitkovsky et al. formulations was solved by the Method of Characteristics. Secondly, the inline technique was implemented in a reservoir pipe valve hypothetical system. The plastic materials mentioned in this paper included high- and low-density polyethylene (HDPE) and (LDPE). Results illustrated the reliability of the proposed technique in attenuating excessive high- and low-pressure surges. However, they evidenced that this technique induced excessive period spreading, thus affecting negatively the operational procedures of the hydraulic system. Lastly, this study provided an estimate of the near-optimal values of the short-section diameter and length.

This paper assessed the branching strategy capacity to mitigate the cavitating flow regime induced into an existing steel piping system. This strategy was based on adding a ramified high or low density polyethylene ((HDPE) or (LDPE)) short penstock to the transient sensitive regions of the existing piping system. The 1-D water-hammer model combined with the Vitkovsky et al. and Kelvin-Voigt formulations was used to describe the hydraulic behavior, along with the fixed grid Method of Characteristics, being used for numerical computations. From the case studied, it was found that such a technique could palliate the cavitating flow regime. In addition, this strategy allowed an acceptable first hydraulic-head peak and crest attenuation. Specifically, positive and negative surge magnitude attenuation was slightly more important for the case of a short penstock made of (LDPE) material than that using an (HDPE) material. Ultimately, it was observed that other factors contributing to the attenuation rate depended upon the short-penstock length and diameter.

This is a study of the hygrothermal behavior of the polyester/glass fiber composite material. The composite material is exposed on a lateral face to different humidity velocity under different temperatures. The kinetics of water absorption follows the Fick’s second law. The water concentration is higher on the surface of the material and it decreases continuously toward the core of the material. The increase of the humidity velocity induced a rise of the diffusion coefficient (D) and the amount of absorbed humidity at the saturation (Mm). Also, the augmentation of the temperature facilities the diffusion process. The fall of the absorption curve is due to the propagation of cracks in the material and the detachment of certain molecular chains. The finite-element software ‘‘Abaqus’’ is used to simulate the humidity diffusion through the composite material. The comparison between the experimental and numerical results shows that the model can predict the hygrothermal behavior of the polyester/glass fiber composite.

The present study considers multiple tandem jets in cross flow under an injection ratio less than 1. The jets are emitted through 60°-inclined, 8 mm-diameter cylindrical nozzles that are razed at different levels from the ground of the working wind tunnel. The understanding of this configuration is likely to provide a good support for the comprehension of more complicated and then real situations. The main objective of this paper consists of the exploration of the different flow structures induced by the emitted jets with the oncoming mainstream in one hand, and with each other and the different domain boundaries on the other hand. A particular attention is dedicated to the established flow field and the induced vortical structures. It is mainly observed that an injection rate inferior to 1 promotes the jets’ flattening and even more the rear jet. A higher injection height, on the other hand, operates differently by providing the jets with a further impulse to cross deeper and higher the mainstream and stay away from the ground attachment effect.

This paper presents a technique for detection and location of faults in polymeric pipelines, by means of transient analysis, of water flows. The method uses transient pressure waves initiated by the sudden closure of a downstream shut-off valve. The presence of faults in pipes partially reflects these pressure waves and allows for the location of any type of fault e.g. leaks. Pressure waves are governed by two coupled non-linear, hyperbolic partial differential equations. The generalized Kelvin-Voigt model was adopted to model the viscoelastic behavior of the polymeric pipes. The fluid pressure head and flow rate are considered as two principal dependent variables. To locate the leak, the mathematical formulation has been solved by the method of characteristics (MOC) of specified time intervals along with Nelder-Mead optimization algorithm for the estimation of the flaw parameters (size and location). The numerical obtained results have shown a good agreement with the experimental data for the detection and the location of leaks.

In this paper, a numerical study is carried out to investigate transient flow of hydraulic installation during the starting period of a centrifugal pump. The pump impeller angular velocity variation is determined by simulating the dynamic law of the pump electric motor. Transient flow equations are solved by using the method of characteristic of specified time intervals. The computed head and discharge, caused by the starting time of the pump, are presented at some cross sections of the pipe. The results have shown that the evolution of the hydraulic variables is well influenced by impeller geometry and the motor torque starting time.

The main objective of this work is to improve particle transport in a sensitive membrane microchannel in order to reduce the detection time of the biosensor. This requires analyzing the effects to improve the performance of the biosensor. Using numerical simulations, we studied the effect of the application of a magnetic field on the kinetic response of the biosensor. Thus the coupling of diffusion convection phenomenon with the adsorption and desorption reaction of the molecules on the Surface Resonance Biosensor Surface (SPR). These simulations are based on Navier Stokes equations, mass transport equations, chemical kinetics equations, and magnetostatics equations. The results found show an improvement in the fluid velocity and subsequently the diffusion and convection mass transport at the biosensor surface.

This paper explored and compared the robustness of the inline and branching re-design techniques used to upgrade existing steel piping systems. These techniques are based on substituting an inline—or adding a ramified plastic short-section at the transient sensitive regions of the steel main pipe. The pressurized pipe flow solver was based on the water hammer model incorporating the Vitkovsky and Kelvin-Voigt formulations; besides, the Method of Characteristics was implemented for numerical computations. The robustness of the proposed protection techniques was tested with regard to a water-hammer event induced into a reservoir pipe valve system. Results demonstrated that both utilized techniques provided a useful tool to mitigate both water-hammer up-and down-surges. Additionally, the attenuation rates of hydraulic-head-rise and-drop were sensitive to the short-section material type and size. Moreover, the branching technique illustrated a marked enhancement compared with the inline one in terms of limitation of wave oscillation period spreading, while providing a surge attenuation rate comparable to that involved by the inline technique. Ultimately, the near-optimal values for the short-section diameter and length were estimated through sensitivity of hydraulic-head peak and crest to the short-section dimension.

This paper proposes a reliability based designing method study for a coupled fluid-structure system. The main objective is to achieve 90% confidance in our estimate of the failure probability. A First Order Reliability Method (FORM) analysis is performed for a double acoustic cavities numerical example. The evaluation of the (FORM) method is established through a reference Monte Carlo Analysis. The results show that the (FORM) method can approximate the confidence goal with a low computation cost.

Drag coefficient and average Nusselt number are a critical operating parameters in fluid-particle processes. In this paper, a 3-D computational fluid dynamics (CFD) software is established to investigate the influence of the particle angle orientation on these parameters. A series of particles (spherical and non-spherical) has been developed and corresponding simulations are validated using correlations with reasonable accuracy. The results show that the average Nusselt number increases slowly with the particle angle orientation increasing from 0° to 30°, and rapidly when the angle orientation increases from 45° to 90°. The behavior gives high heat transfer, especially on the upper and front side of the cylinder when the gas velocity is high.

Muscle activation can be quantified by surface Electromyography (EMG) measurements. Indeed, EMG is a technique used to measure the potential charge of muscle fibers during isometric, concentric or eccentric contractions. The aim of this paper is to design an embedded electronic system allowing the detection of the EMG signals. The measured data is then sent through a wireless transmission system to the host computer. Wireless transmission has the advantage of facilitating the capture of the human movement and eliminates electrical wires. The paper is divided into three sections. Firstly, this work will begin with the realization of an embedded system to measure EMG signals. This signal is detected by surface electrodes placed on the muscles. Then, EMG signal analysis will be performed by different processing methods. Finally, these experimental data will be manipulated and used as inputs to musculoskeletal model for estimate isometric muscle forces. As a result, the modelling method presented represents a good way to estimate muscle forces during isometric contraction.

The bone is a hierarchically structured material with mechanical properties depending on its architecture at all scales. It’s important to take account the impact of Water which plays a significant role in the bio-mineralization process and serves as a plasticizer, enhancing the toughness of bone. In this study, a trabecular bone multiscale model based on finite element analysis was developed to link scales from nano to macroscale in order to predict the orthotropic properties of bone at different structural level. An inverse identification algorithm is used in order to identify the orthotropic properties. Furthermore, the effect of water is incorporated. Good agreement is found between theoretical and experimental results.

This current study is considered as a continuation of previous research in which static and cyclic tests were performed in accordance with the ISO 10328 standard on trans-tibial sockets made from natural fiber in order to characterize their mechanical performance. The experimental findings of the fatigue test have revealed a viscoelastic behavior of the composite material of the tested socket. In addition, it has been proposed to model the fatigue test by the Burgers model since it better fits the experimental results presented by fatigue curves. Two main objectives are distinguished. The first one is to identify the parameters of the Burgers model; the second one is to evaluate the natural frequency of the bench structure: Socket, Artificial stump and Test device Assembly used to perform the mechanical tests. The natural frequency, which is deduced from an electro-mechanical analogy method, is then used to optimize the design of the test device.

The present paper proposes an insight into the objective quantification of internal parameters through experimental tests and numerical simulations of contact-free creep tests. The study investigates effects of applied pressure and dwell-times of contact-free creep tests on the viscoelastic properties of human skin. The skin is seen as a homogeneous, quasi-incompressible, linear, isotropic and viscoelastic material modelled by the Zener’s rheological model. A Finite Elements model is developed and an inverse approach is used in order to identify the viscoelastic parameters. Analysis of variance (ANOVA) is carried-out to assess intra- and inter- related effects for two protocols. The analyzed results prove that the imposed pressure exhibits a major effect on the identified viscoelastic properties. However, the dwell time has no remarkable effects. Moreover, the major conclusion establishes that a loading pressure of 1 bar allows to distance objective quantifications from possible protocol influences.

Orthodontic therapy generally begins with aligning and leveling phase, wherein a NiTi, superelastic wire is habitually attached, tied and activated to supply the required forces for teeth correction. Deactivation of the archwire following teeth movement will commonly lead to the sliding of wire through the adjoining bracket slots. This study aims to investigate the friction and wear behavior of a deflected NiTi wire sliding against a 316 stainless steel sample with the effect of changing the temperature and the shape of the wire. Superelastic NiTi wires with circular and rectangular cross-section were tested, in Fuzayama artificial saliva and at the temperatures met in the oral cavity, using a modified rotative tribometer. It was found that the tested parameters had a great effect on the tribological behavior of the studied tribo-couple. Indeed, the results showed an increase in the wear rate as the temperature increase because of the rise of the thermal stress within the tested NiTi alloy. It was also found that the wear of the rectangular archwires is more significant than the circular ones, this could be due to the nature of the initial tribo-contact condition.

In recent years, cavitation is increasingly utilized in a wide range of applications in the biomedical field. Monitoring the temporal evolution of cavitation bubbles is of great significance for efficiency and safety in biomedical applications. Cavitation is characterized by a random phenomenon that causes problems of re-producibility. This could be at the origin of the damage on the vascular walls and the adjacent fabrics of the handled organ. Better control and regulation of the cavitation’s activity during the ultrasonic treatment would establish an inescapable way to envisage the development of a therapeutic device. This thesis work aims at developing a model allowing the regulation of the acoustic cavitation. This improvement could have direct applications in the medical field. This paper presents a theoretical study on the modeling of acoustic cavitation in the medical field and a numerical study of the simulation of acoustic cavitation. The study of acoustic cavitation by current CFD numerical simulations is also of great interest. For numerical simulation, we used OpenFOAM which is a toolbox for the dynamics of computer fluids as free software to access codes and algorithms.

This paper presents a comparative study between the nonlinear dynamic behavior of an unbalanced rigid rotor in a short hydrodynamic bearing and of an unbalanced rigid rotor in a long hydrodynamic bearing. Two nonlinear mathematical models with two degrees of freedom are used in this investigation to predict the movement of the shaft and its bifurcations. Nonlinearity is introduced into models through analytical expressions of hydrodynamic forces. These analytical expressions are determined by the integration of the oil pressure distribution into the bearing using the short bearing approximation and the long bearing approximation. The numerical integration method is applied to determine the bifurcation diagrams using the rotor speed as a control parameter. In this study, Poincaré sections, frequency spectrum, motion orbits, and bifurcation diagrams are used to characterize the shaft motion. Several nonlinear phenomena such as jumping motion, multi-periodic oscillation, quasi-periodic motion and chaotic motion are predicted. It has been found that the effect of unbalance is very important on the stability threshold speed and on the amplitudes of the oscillations for the case of a short bearing. However, the unbalance effect is negligible in the case of a long bearing.

Three axle gear oils (75W90-A, 80W90-A and 75W140-A), available on the market and labeled as “Fuel Efficient”, and two candidate products (75W85-B and 75W90-B) were selected and their physical and chemical properties were measured and compared. The friction torque inside rolling bearings lubricated with the five axle gear oils was measured in a dedicated test rig. The measurements and the corresponding numerical simulations indicate that friction torque inside rolling bearings is strongly dependent on the operating conditions and on the axle oil formulations. The model was then applied with success to predict the torque loss in gearbox rolling bearings, in particular, those used in the FZG machine slave and test gearboxes. Gear power loss tests were realized on the FZG gear test machine, using type A10 gears and severe operating conditions. The torque loss measurements and the corresponding numerical simulations clearly pointed out the influence on the base oil type, of the oil viscosity and of the additive package on gear torque loss promoted by different axle oil formulations. An average coefficient of friction between meshing gears was devised from the experimental results. Several aspects regarding the meshing gears power loss were investigated like gear loss factor, the coefficient of friction and the influence of gear oil formulation (axle gear oils). A gearbox total power loss can be predicted by estimating the several power loss sources dissipated in gears, bearings and seals.

In this work, we propose uncertainties propagation study for a coupled fluid structure system. It focuses on the designer needs to predict the vibro-acoustic behavior of systems with uncertainties properties and improve the product quality by mastership the variation sources. The proposed strategy is made by four main steps. The first one is to select the random design parameters according to their sources and their significance level. The second step uses a hypercube latin sampling technique as a reference in the deviation range of Six-Sigma. The third step uses a model order reduction technique. The fourth and last step compares the approximated stochastic responses by a polynomial chaos expansion (PC) to the reference. The computational cost (CPU time) and the accuracies of the proposed strategy are compared and discussed for the extreme statistics and the mean behaviors output results. The performances of the suggested method are established through a double walls numerical example using a stochastic finite element method (SFEM).

This paper addresses the issue of wave propagation features in a honeycomb sandwich plate over a broadband frequency range. The special emphasis putted on such materials is due to their growing industrial integration resulting from interesting mechanical and material properties, such as high energy dissipation and resistance/weight ratio. A two-dimensional spatial Discrete Fourier Transform (2D-DFT) is employed with experimentally measured displacement field, as primary input, to identify a complete wave propagation direction-dependent dispersion equation of the sandwich plate. Valuable insights into the wavenumber-space (k-space) profiles, in relation with the structural orthotropic behavior, are highlighted. The 2D-DFT method is proved to be efficient in a deterministic framework. Nevertheless, its robustness against input parameters’ uncertainty needs to be evaluated as well to achieve more realistic k-space characteristics’ identification. The impact of measurement points’ localization’s uncertainty on the 2D-DFT identifications is statistically investigated. The obtained results show the large variability of the identified k-space parameters and reveal the important identification sensitivity to such measuring errors involved in the experimental manipulations.

Recently the author proposed a new In-Operation modal identification algorithm, namely the Stochastic Modal Appropriation algorithm (SMA) which identifies the frequency and the damping ratio simultaneously in a single step. The key idea is to rotate parametrically the outputs correlation sequence so as it looks like the system impulse response. We show in this work that SMA rejects automatically harmonics as well as spurious/numerical modes leading therefore to physical-only modes identification. After a mathematical proof, the method is validated on a simulated system.

Due to the evolution of design techniques and material qualities in civil engineering, the structures become lighter. When these structures will be located in environments prone to earthquakes or high winds, this lightness may accentuate the vibration causing major problems to structures such as failure, discomfort, noise… Currently, many researchers are interested in this problem to balance between lightness and vibration resistance. From the review of the literature, several methods are proposed in this field, the most used one is based on the principle of the control of vibration. In this case, the reduction of structural vibrations is done by adding a mechanical system composed of intelligent materials. In this paper, the performance of the control system, such as a passive control using tuned mass dampers TMD and/or an active control using active tendons AT and ATMD on a high building subjected to seismic excitation, is studied. A parametric study is conducted by varying a certain key parameter such as the position, the number and the type of the control systems. Finally, to find the ideal position of the active system, three techniques are proposed: method of modal controllability, controllability index and genetic algorithm. For all the cases, numerical simulations are established at MATLAB and the results are illustrated and compared.

In this paper, elasto-plastic model based on non-associated flow rule is implemented in Abaqus/Explicit software via VUMAT subroutine to study the influence of some process parameters: cone wall angle, tool diameter, and sheet thickness, on the formability, plastic deformation and thinning during single point incremental forming (SPIF) process. The present work presents useful guidance to show the effect of these three parameters in improving the quality of manufactured products and in obtaining a better formability during SPIF process.

Incremental sheet metal forming process is a new procedure that forms three-dimensional parts of metal in a thin sheet. In particular, single point incremental forming of sheet metal is considered as a process that forms products without using complex dies and specific forming tool. Through this process, a cylindrical rotating punch with hemispherical end shape follows a predefined continuous or discontinuous trajectory to deform the sheet plastically. This fabrication method is known for its flexibility and the adaptation to complex geometrical shapes [6]. In the present work, the single point incremental forming process (SPIF) has been investigated experimentally and numerically using 3D finite element analysis (FEA). Regarding concerns of the material, the sheets were produced from aluminum alloy. This study focuses on using numerical simulations as a tool to predict and control some mechanical and geometrical responses. In order to understand the effect choice of model constitutive laws, we intend to compare between two relationships of stress-strain hardening behavior, implemented on ABAQUS software, with the experimental results. Based on the obtained findings, a comparison study was presented in this paper between experimental and numerical results. Different outputs responses were extracted such as global geometry (springback error, shape and final achieved section profiles) and thickness distribution. Therefore, the results obtained from the simulation were validated experimentally and good correlations are found, also the process strategies show good agreement with the experiments. Simultaneously, we conclude the most efficient hardening behavior of the material that insures the obtaining of results that are as close as possible to the experimental ones.

The automobile chassis is manufactured from various metal formed parts that are joined together mainly by welding. Under same load conditions, each material behaves differently depending on its properties. The knowledge of these properties is crucial and requires experimental data. For an isotropic material model, the data needed can be extracted from a simple tensile test. But, for orthotropic materials, more experimental equipments are necessary. In such cases, the finite element method can be used for the numerical approximation of the problem. In this paper, a numerical modeling of the mechanical response of an Interstitial Free (IF) steel subjected to a low strain rate tension is described, in the particular case of isotropic linear elasticity and orthotropic plasticity under the isotropic hardening assumption. The modeling of the material behavior related to the ductile fracture was based on the approach of Hillerborg et al. (Cem Concr Res 6(6):773–781, 1976, [1]). Firstly, the theory behind the model was explained. Afterwards, the finite element model was described and the related parameters were defined. Finally, the numerical results, performed using the finite element software ABAQUS®, were compared to the experimental data determined through the tensile tests carried out by Cumin et al. (Tech Gaz 23(1):229–236, 2016, [2]) on the HC260Y steel.

The present paper focuses on the determination of the optimum cutting conditions leading to minimum cutting force (Fa, Fr, Fz) as well as cutting power in the case of the turning of the Inconel 718 using the tool holder referenced by SVV 2020 K-11 and the carbide double-sided 35° rhombic cutting tool. The optimization is based on the Taguchi method. Furthermore, the orthogonal array, the signal-to-noise ratio (S/N) and the analysis of variance (ANOVA) are respectively exploited to establish the statistical significance of the cutting parameters on different technological ones studied. Three parameters are studied in this paper, namely: feed rate f, nose radius rε and cutting speed Vc. The experimental results revealed that the nose radius is the most factors influencing the three cutting force components followed by the cutting speed for the feed force and the feed rate the two other components. Moreover, a mathematical model relating both of cutting force and cutting power to the cutting parameters were developed.

Incremental forming of sheet metal is a new sheet forming process. He has shown a variety of applications ranging from the automotive field to the biomedical field. However, sheet metal parts cannot be made in a one-step incremental forming process because the maximum profile angle of the wall that can be formed is limited for a given sheet material and for a given thickness. This limitation can be overcome with the multi-step incremental forming process (MSIF). In the framework of this study, it is proposed to analyze by experimental techniques the thickness and the profile of a truncated cone obtained by several steps forming an incremental MSIF. The study has been carried by forming a conical cup with 85° wall angle in four stages. Experimental tests were performed for specific conditions such as forming strategy, tool path, increment and cutting parameters. ABAQUS numerical simulations were performed to validate the experimental results at the end of each incremental forming step. The numerical and experimental results of the profile sheet metal are the subject of a comparative study between the theoretical, simulated and experimental models.

Human resource skills have a significant impact on the production systems performance and competitiveness of companies. In fact, many companies are aware of the human potential in their development, to improve their overall performance and to cope with global economic and technological changes. Hence the need for any company to assess its staff potential and to put into place relevant training plans becomes a crucial challenge, in order to meet its current and future needs. Employees’ competencies assessment includes all the activities related to the planning, monitoring, evaluation, recognition and development of individual work performance. In this paper, we present a method to evaluate the human performance based on the job and skills management, in order to improve industrial performance. This assessment relates to the analysis of the data and information gathered from surveys of employees working in a company’s cosmetic production departments.

Fused deposition modeling FDM is an additive manufacturing technology (AM) at fast growing and that could enhance manufacturing because of its ability to create functional parts and highly innovative with suitable mechanical properties having a complex geometric shape. Various process parameters used in FDM affect the quality of the prototype. The control of these specific parameters involved during the manufacturing is an important activity. For this, the parameters of the 3D printer must be identified and controlled in order to study and optimize their influence on the mechanical properties of prototypes printed using the Taguchi method. The thickness of the layer and the filling orientation are the most influential on the modulus of elasticity and the tensile strength, respectively. Furthermore, the thermomechanical behavior by DMA tests and the requirements to optimize the factors generated by the FDM technology.

High speed machining is a suitable process to increase the productivity and reduce the cost during manufacturing. Delamination factor (DF) is the main inconvenient while composites drilling. In this work the high speed milling used for drilling carbon fiber reinforced plastic composite (CFRP) with different parameters such as hole size, cutting speed and feed speed. The Response surface methodology (RSM) was used with the Central composite design (CCD) to predict DF in function of different combination of machining factors. The analysis of variance (ANOVA) used for evaluation the effect of the studied factors on the composite. Experimental results showed that the DF at the inter hole is greater than the DF at the exit hole which have a significant effect on the hole size.

The surface roughness is a decisive criterion for the quality of the machined surface. Many researchers are interested to study the effects of the machining parameters on the surface quality as: the cutting conditions, the machining strategies, the tool geometries and the machining errors. All these studies are developed for the stationary feed rate and neglected the cinematic effects caused by machine deceleration and acceleration when the tool trajectories change a direction. The objective of this research was to investigate the effect of the velocity changes on the surface roughness. A set of machining tests in high-speed end-milling of the 42CrMo4 material by a ball nose end-mill is made. For the same cutting conditions, the roughness is measured on three zones respectively the acceleration, the stationary and the deceleration zone. It was seen that the cinematic change causes a poor surface roughness.

The present paper consists of an experimental study to the effect of turning parameters on surface roughness of Cobalt alloy (Stellite 6) and the optimization of machining parameters based on Grey relational analysis. Taguchi’s design of experiments (DOE) is used to carry out the tests. The response surface methodology is successfully applied in the analysis of the effect the turning parameters on surface roughness parameters. Second order mathematical models in terms of machining parameters are developed from experimental results. The experiment is carried out by considering four machining conditions, namely noise radius, cutting depth, cutting speed and feed rate as independent variables and average arithmetic roughness as response variables. It can be seen that the tool noise radius and feed rate are the most influential parameters on the surface roughness. The adequacy of the surface roughness model was established using analysis of variance (ANOVA). An attempt was also made to optimize cutting parameters using a Grey relational analysis to achieve minimum surface roughness and maximum material removal rate.

The vibrations in orthogonal milling are simultaneously due to the friction between the tool and the workpiece and to the flexibility of the cutting system, leading to chip section variation to cause the chatter phenomenon. Indeed, these vibrations induce an increasing machining disorder leading to an unstable cutting to cause a poor surface quality and a rapid tool wear, in addition to different operational risks. This work presents a numerical approach to establish cutting stability lobes in orthogonal metal milling. The Abaqus software is used to perform the simulations, the Johnson-Cook laws are considered for the workpiece material strength and fracture, the Coulomb law is retained for the friction between the workpiece and the tool, the tool is considered flexible, and the thermal conductivities of the workpiece and the tool are introduced. The results at various cutting speeds are obtained for different tool flexibilities: radial, transversal, and combined; and are then compared to conclude on the cutting stability lobes.

In this study, artificial neural networks (ANNs) were used to study the effects of machinability on cutting parameters during turning of the cobalt alloy (Stellite 6). Cutting forces with three axes (Fx, Fy and Fz) were predicted by changing the tool tip radius (r), cutting speed (Vc), feed rate (f) and cutting depth (ap) with conventional lubrication. Experimental studies were conducted to obtain training and test data and a feed-forward back-propagation algorithm was used in the networks. The main test parameters are the tool tip radius (r, mm), cutting speed (Vc, m/min), feed rate (f, mm/rev), cutting depth (ap, mm) and cutting forces (Fx, Fy and Fz, N). r, Vc, f and ap were used as input data while Fx, Fy and Fz were used as output data. The mean percentage values of root mean square error (RMSE), mean absolute percentage error (MAPE) and mean absolute deviation (MAD) for Fx, Fy and Fz using the proposed models were obtained around 2 and 4.79%, respectively for training and testing. These results show that ANNs can be used to predict the effects of machinability on cutting parameters when cutting Stellite 6 on turning process. The results highlighted the performance of the studied configuration.

The purpose of this paper is to explore the buckling problems of functionally graded conical shells due to thermal loadings. The response is obtained for a uniform increase in temperature along the thickness direction of the shell. The equations governing the behavior of the conical shell are written from the modified Reissner-Mindlin formulation. Properties of the shell are estimated using the Voigt rule of mixture via the power function. The temperature dependence of the material constituents is also considered. A comparison study of the obtained results with those available in the literature is presented in order to validate the proposed model. Then, the effects of the power-law exponent and geometrical parameters are examined.

In this present work, an attempt has been made to produce metal matrix composite using Al 2017 alloy as matrix material reinforced with graphite particles using stir casting technique. Initially, Al 2017 alloy charged into a crucible was superheated in the furnace. Besides, preheated graphite particles were dispersed into the vortex of molten 2017A alloy. The mechanical stirring was carried out to improve wettability and distribution. The composite mixture was poured into a non-permanent mold with including the form of normalized specimens tensile. Different Microstructures of Al 2017 alloy matrix composites showed more porosity. Thermal conductivity of the prepared composite was determined before and after the addition of graphite particles to note the extent of improvement.

This paper presents material and geometric nonlinear analysis of ceramic/metal functionally graded cylindrical shell using a user-defined subroutine (UMAT) developed and implemented in Abaqus/Standard. The behavior of the ceramic/metal functionally graded cylindrical shell is assumed elastoplastic with isotropic hardening according to Ludwik hardening law. Using the Mori–Tanaka model and self-consistent formulas of Suquet, the effective elastoplastic material properties are determined and are assumed to vary smoothly through the thickness of the cylindrical shell. The effects of the geometrical parameters and the material distribution on nonlinear responses are examined.

This paper presents a higher-order solid-shell element for buckling behavior of carbon nanotubes reinforced functionally graded shells based on higher-order shear deformation concept. Four different types of reinforcement along the thickness are considered. This finite element is used to study the buckling behavior of carbon nanotubes reinforced functionally graded shells and to investigate the influence of same parameters on the buckling behavior.

The static behavior of carbon nanotubes reinforced functionally graded shells is studied using the enhanced assumed strain (EAS) solid-shell element based on higher-order shear deformation concept. Four different types of reinforcement along the thickness are considered. Furthermore, the developed solid-shell element allows an efficient and accurate analysis of carbon nanotube-reinforced functionally graded shells under linear static conditions. The influences of some geometrical and material parameters on the static behavior of shell structures are discussed.

This paper present a study of the effect of the type of binder on mortars properties reinforced with Doum palm fiber. Two types of binder used for the production of mortars containing Doum palm fiber. Cement is used as a binder for mortar 1 and plaster is used for mortar 2. The mass content of fiber in the test samples was varied from 0.5% to 1.5% with a step of 0.5%. Thermal characteristics of specimens in term of conductivity and diffusivity were studied. Moreover, the flexural and compressive strength of the samples were evaluated. The measurement of the thermal properties of the specimens shows that plaster has the lowest values of thermal conductivity. A report between densities and mechanical properties of these mortars was realized. These results also report that the density of the specimens has an important role in mechanical properties. The more porous is the material present the lower thermal conductivity. For both mortars, the use of Doum palm fiber improves the mortar ductility without affecting the mechanical requirement for construction materials.

Deep drawing process is commonly used to produce particular components like aerospace and automotive structural parts. Based on the drawing ratio, it can be performed in a single or a multiple-stage drawing. Due the complexity of this process, finite element simulations are considered as a powerful tool for the both reasons: reducing times and costs, and improving quality and productivity. The current study is conducted to evaluate the performance and the capability of a non associated flow rule (NAFR) approach on numerical results during reverse re-drawing process of DDQ mild steel metal. The adopted model is implemented on ABAQUS software using user interface material subroutine (VUMAT).

Due to their crystallographic texture, sheet metals generally present a significant anisotropy. The DD13 sheet metal is one of the hot-rolling steels, also called mild steels that is designed for deep and extra deep drawing applications. It is characterized by high fracture elongation and suitable for chassis components and wheel outer borders. A finite element (FE) -implementation of an anisotropic plasticity model coupled with damage and isotropic hardening for the DD13 metal in low velocity impact simulations is performed. The elasto-plastic model includes isotropic elasticity, anisotropic yielding, associated plastic flow and isotropic hardening. The plastic-damage model is implemented into a user-defined material (VUMAT) subroutine for the commercial finite element code ABAQUS/Explicit. Material properties are defined using the experimental results of (Ghorbel et al (2019) Int J Mech Sci 150:548–560, [1]). A parametric study of the effect of anisotropy, -plate thickness and impactor properties is carried out. The numerical results of the impact force history and impact velocity are discussed and validated.

Elastic-plastic properties of thin films deposited on elastic-plastic substrate were extracted using numerical nanoindentation tests from the force-displacement curve. In order to limit the substrate effect on measuring thin film elastic-plastic properties, three theoretical models were studied in this work. All these models use a parametric identification method based on dimensional and finite element analyses to extract relationships between the indentation parameters and the elastic-plastic properties of the film and the substrate. The mechanical properties of several thin films were identified using these models.

Single point incremental forming (SPIF) which does not require any high capacity press machine nor a set of dies with specific shape, is an emerging sheet metal forming technology, capable of manufacturing complex parts at low cost for small to medium-batch production. This method is explained by the small plastic deformation caused by the force applied by a small punch on a sheet. The main reason to carry out such a process is to take the advantages of materials with different properties, such as high strength, low density, low price, and corrosion resistibility, at the same time and in a single component. The usage, of bimetal sheet is also justified because of the combination of the advantages offered by both materials of which it is composed and to a reduction of the disadvantages presented by each material if taken separately. The study presented in this research paper concerns a numerical investigation conducted on the incremental sheet metal forming process of Al and Cu bimetal composite. The finite element (FE) model validation was performed to compare the results obtained from the numerical simulations with experimental data available in the literature. The effects of process factors, which are considered as input parameters, such as: the tool diameter, wall inclination angle and layer arrangement, were investigated with finite element method (FEM) approaches on the forming time (the required time to forming the sheet), forming forces (the required forces to form the sheets), dimensional accuracy and maximum thickness variation (the maximum difference between initial thickness and formed sample thickness) of a truncated pyramid. The composite sheet behavior in a forming process differs from single-layer sheets and depends on the layers arrangement (contacted layer with the tool) and thickness. In this regard, the effect of layers arrangement on the forming behavior of (Al/Cu) bimetal sheet is of particular interest in the present study. Therefore, several tests were conducted to investigate the influences of some other variables, such as layers arrangement on the formability of the sheet material in a single point incremental forming process and the variations of force versus time diagram, defined as outputs.

In this paper, we will study the influence of multiple laser impacts on thin leading edges of a turbine blade. A numerical analysis based on a 3D finite element method of thin leading edge specimens of a turbine blade made of titanium super-alloy (Ti–6Al–4V) is performed using the commercial software ABAQUS. A repetitive time Gaussian increment pressure that is uniformly applied at a square affected region is used to characterize the LSP loading. We apply the visco-elastic-plastic of the Johnson-Cook law coupled with damage in order to develop the treated material behavior law. The objective of this simulation is to predict the mechanical surface modifications generated by the laser shock processing: (i) the residual stresses, (ii) the plastic strains and (iii) the Johnson-Cook superficial damage. These modifications are well analyzed for thin leading edges of a turbine blade treated by a square laser spot that can effectively treat a considerable part with a coverage rate that is below 5% comparing with a circular laser spot.

This paper focuses on the relation between the rheological and the morphological properties of immiscible polymer blends. Polystyrene droplets (PS) have been synthesized in the laboratory. The blends of EVA2840/PS at ratios 90/10, 70/30, and 50/50 (wt%/wt%) were prepared by Rheomix HAAKE 600VR internal batch mixer with roller rotor. Rheological tests were made at a temperature of 140 °C. Rheological measurements using a rotational rheometer with parallel-plate geometry are considered in order to lead to a better understanding of the dispersion of the PS droplets. Rheological examinations showed that the storage, the loss moduli, and the complex viscosity of blends have an extra elasticity at lower frequency. As a result, analysis of Han diagrams revealed that EVA2840/PS blend are immiscible.

Stators of electrical machines are manufactured by ferromagnetic sheet metals blanking. The literature shows that the magnetic efficiency depends on the mechanical deformation/stress states. Thus, the simulation of manufacturing processes leading to the mechanical deformation mapping coupled to a magnetic behavior model can be useful in the design of the rotating machines. This work focuses on a magneto-mechanical coupling approach applied to a stator teeth blanking. An experimental characterization of the magnetic behavior of a Fe–Si alloy under tensile tests is done. The magnetic behavior is described by Jiles–Atherton model. An extended formulation is then proposed to model the magnetic behavior under mechanical deformation. Genetic algorithms are used to identify the corresponding hysteresis parameters. Finite element simulation of teeth blanking is done under Abaqus. This simulation allows us to access to the deformation states on the blanked sheet. A Python code is implemented to extract the plastic equivalent strain for each element mesh from the finite element simulation. Then, according to the extended Jiles–Atherton model, the corresponding magnetic induction is calculated. Finally, a new Abaqus output is created, called magnetic induction, and is injected into the Abaqus file to depict the magnetic parameter distribution. Results show the magnetic induction distribution and signpost that the magnetic degradation reaches 24% near the cut edge. The affected zone is 1.5 mm large.

Nowadays, the world is experiencing many changes, the technology is conquered by open hardware movement and the competition is based mainly on the development of ground-breaking products. These technological and economical changes are pushing companies to reinvent themselves to develop products that are cheaper, better and of good quality than competitors. An appealing avenue for these companies is to use open hardware solutions in the development of their new products. However, product development processes used nowadays are not suited to exploit the full potential of open hardware. This work addresses this issue by first performing an in-depth assessment of the academic literature on product innovation processes and later proposing a product development process based on open technologies. The process introduces a new product development rationale that includes four phases: the first phase is looking for opportunities, which involves generating opportunities and creative ideas. The second phase is the opportunity assessment phase, which consists of selecting and capturing opportunities. The third phase is the validation of opportunities phase through technical feasibility, client desirability and sustainability. The fourth phase is engineering design, which includes concept generation, prototyping testing, and product manufacturing. The developed process hopes to open the way for businesses, especially in emerging countries like Morocco, to be competitive on the market by helping them designing superior products based on open technologies.

Sandwich materials are potential candidates instead of traditional materials in several fields as aerospace, civil engineering and automotive because of their mechanical properties and especially their high ratio bending stiffness to weight. Three-point bending is a frequent process for forming sandwich panels before usage. This study presents an analysis of the damage of the sandwich panels during quasi-static tests in three-point bending. Experimental tests leading to the failure of the core of the sandwich material were carried out. Finite element analysis was also conducted for the numerical prediction of observed damage. Also, analytical Gibson’s modified model is considered to obtain the critical loads leading to the failure of the sandwich panels. This allows constructing a mode map for failure modes of sandwich panels in three points bending process.

Classical fracture models assume that the stress triaxiality is the key parameter controlling the magnitude of the fracture strain. However, recent works shown the influence of other parameters that characterize the stress state on the prediction of fracture strains. In this work, two uncoupled fracture models, Mae and Wierzbicki [8] and Xue and Wierzbicki [9], were analysed using finite element models. These models define a ductile fracture locus formulated in the 3D space of the stress triaxiality, Lode angle parameter and the equivalent fracture strain. The material selected was a cast A356 aluminium alloy for which the model parameters were previously defined. Two groups of tests are analysed in order to provide additional information on the material ductility. The first corresponds to plane strain tests carried out on flat plates with different grooves. The second corresponds to uniaxial tension tests applied on smooth and notched round bars, which were designed with different notch radii. These specimens allow covering a wide range of stress triaxiality. The present work extracts the evolution of the equivalent plastic strain at fracture, the stress triaxiality and the Lode angle parameter in order to evaluate the possibility of using either smooth and notched bars tests or smooth and notched bars tests and grooved plates to evaluate the 3D locus for high values of stress triaxiality. In this context, a new function is proposed to describe the equivalent plastic strain at fracture based on the stress triaxiality and the Lode angle parameter.

Incremental sheet forming (ISF) process is a new manufacturing process where no dedicate dies are needed, neither are specific tools. In fact, it consists on deforming a sheet plastically in progressive way. This plastic deformation is caused by applying a vertical force generated by hemispherical punch piloted with a CNC machine into a thin sheet. This process has been applied to metals and polymers. However, few researches are made in the field of composite materials. In fact, this type of material shows higher properties than each material if considered independently. Recently, some research works are published, in particular those related to bimetals sheets. These findings open a new area of scientific researches. In other hand, the application of single point incremental forming (SPIF) on bilayers materials gain a lot of interest. In this study, we present a finite element analysis (FEA) of SPIF applied to Titanium-Steel bimetal sheet (Ti/St). The present work aims to predict the effect of some parameters such as layer arrangement and step size on the forming forces evolution and the thickness distribution of a truncated pyramid. Precisely, layer arrangement constitutes one of the major factors influencing the material formability and the load applied by the punch. Results show that higher forming forces are obtained when the upper layer is steel.

The purpose of the present work is to investigate experimentally the mechanical fatigue behavior of unidirectional flax and carbon fiber reinforced composites. Static and fatigue bending tests were realized on laminates made of flax and carbon fibers impregnated with an epoxy resin. Displacement-controlled bending fatigue tests were conducted on standard specimens with a mean displacement of 50% of the ultimate failure displacement. Specimens were subjected to an applied displacement level of 70% until 104 cycles. A comparison of the fatigue properties of the flax and carbon fiber composites was made. The stiffness degradation curves show that carbon composites have higher resistance than flax composites. Hysteresis cycles, dissipated energy and loss factor evolution were measured and discussed. The results obtained show that the flax fiber composites have a damping property higher than the carbon fiber reinforced composites under fatigue bending tests.

Auxetic structure became the center of attention in the recent years because of their abnormal properties such as negative Poisson’s ratios. These materials exhibited many benefits like strength, higher stiffness and energy absorption, in comparison with conventional ones. This article presents the mechanical characterization of a bio-based sandwich structure with an auxetic core. The structure has been manufactured using additive manufacturing (3D printing technology). The core and the skins are made from the same biological material which is the polylactic acid. Thus, the sandwich structure is 100% bio based which makes it recyclable. Different density of the auxetic structure was studied in order to evaluate their influence on the mechanical properties of the sandwich. Uniaxial loading was performed on the skins in order to obtain the mechanical properties of the materials and on the core to obtain the Poisson’s ratios. Then, the sandwiches were tested in three points bending. The flexural and shear rigidity were measured for each beam. The results obtained showed that the auxetic core density plays a major role on the mechanical characteristic of the sandwich structure.

The CrN/CrAlN/Cr2O3 multilayer coatings were deposited by reactive magnetron sputtering DC on 90CrMoV8 stainless steel under various oxygen flow rates. The structure and crystalline phases are characterized by the x-ray diffractometer. Through SEM, a dense and coherent is revealed in CrN/CrAlN/Cr2O3 multilayer coatings. The friction and wear behaviors obtained with the ball-on-disc test show that all multilayer films exhibit a good wear resistance, especially the one with an oxygen flow rate of 10 sccm. Nevertheless, in sea water the film without a top layer of Cr2O3 have the lowest coefficient of friction. This behavior is attributed to the interfacial strengthening and the existence of the upper passivation layer Cr2O3. Adding to that, the film obtained under an oxygen flow rate of 10 sccm show the lowest grain size and the maximum hardness and elastic modulus could respectively, 45 and 417 GPa.

This work involves discovering an experimental study in the mechanical behavior of Glass Fiber Reinforced Cement (GRC), which is a composite material consisting of Portland cement and chopped alkali-resistant glass fibers. For that, a series of bending and compressive tests were carried out on GRC specimens. In order to identify the mechanisms of damage and detect the cracks of these structures, microscopic observations have been made using Environmental Scanning Electron Microscope (ESEM). These observations show that the breakdown of the matrix and fibers are the dominant damage mode.

The present work aims to numerically investigate the pressure behaviour of adhesively bonded interlocked composites tubes. To this end, a finite element model has been investigated based on the meso-model (interface and ply) concept. The identification of the model parameters has been carried-out through fracture mechanical tests and cyclic tensile tests on [±45] and [±80] specimens. The mathematical models as well as the experimental tests of both interface and ply are presented. It has been proved through numerical outcomes that the joined tube outer diameter is proportional to the applied pressure.

Nitriding is an important industrial process to improve the mechanical properties of components, especially by producing compressive residual stresses. Gas and ion nitriding has become a popular thermo-chemical surface treatment, which is being used to develop thermal/mechanical fatigue and wear characteristics of steels. In this study, the gas and ion nitriding of AISI 4140 steel was carried. The micro-structure, the micro-hardness, the residual stresses distribution and the crack resistance of the hardened steel are determined. These analysis and characterization are carried out using optical microscopy, scanning electronic microscopy, X-ray diffraction and mechanical measurements (micro hardness and residual stresses) of treated material. The results are intended to contribute in defining and optimizing the adequate choice of treatments for this type of steel in industrial conditions. The gains, expressed in term of endurance limit, brought by these treatments are established by three-points bending fatigue tests and discussed in relation to the residual stresses evolution under the cyclic loading conditions. The fatigue fracture resistance is analyzed by methods of fracture mechanisms. This reveals that the gain provided by the gas nitriding (50%) is about 8% against 32% for the ion nitriding. This is primarily allotted to a high level of compressive residual stresses for ionic nitrided state compared to the gas nitrided state.

The aim of this study is to characterize the link between the cutting conditions used while trimming a composite material glass fiber reinforced polymer (GFRP) and the surface quality by characterizing the area roughness of the machined surfaces. In the experimental evaluation, a central composite design with 20 combinations was used to study cutting parameters (cutting speed (Vc), radial engagement (ae) and tooth feed (fz)). The area roughness parameters (Sa, Sq, Sz) were measured by a KEYENCE VHX-6000 3D profilometer. Response Surface Methodology (MSR) were used to determine mathematical models using experimental data.

The applications of titanium alloys are traditionally present in the field of transportation, basically in aircraft engines and turbo-reactors. The major advantage of these titanium alloys is linked to their exceptional mechanical behavior presenting a good mechanical resistance in different conditions of solicitations, an important duration of life associated to a low density; these are capital parameters for this kind of applications. Therefore, titanium (mainly TA6V alloy) is now widely used in the conception of high precision manufactured products such as airplane’s engine and airframes skin including fan blades for turbojet engine demanding such advantages. The present work considers the study of the plastic behavior of TA6V as an aerospace material alloy. To achieve such finality, a modeling study followed by an identification strategy is imposed. Thus, the use of constitutive law taking into consideration the microstructural state of titanium is essential to have a reliable model for a further implementation in finite element software. The results found by this modeling study and the identification using CPB06 and Barlat Yield 91 as plastic criteria, will serve to study the anisotropic mechanical behavior of this material under several solicitations.

Fall injuries are experienced worldwide ranging from fatalities to hospitalization especially in Elderly population. The available soft flooring options are restricted to specific buildings and location. The study developed soft flooring material incorporating crumb rubber from waste tyres to provide cushion effect in flooring to induce cushion effect. The concrete specimens were developed in form of tiles/slab with varying thickness of 10, 20 and 30 mm. In total 36 specimens were tested with 3 × 2 blank reference specimen without crumb rubber. The specimens were tested in accordance to the force required to cause fracture in human leg bone (192 N) while the testing energy was 198 N. The height of drop was kept 45 cm. The softness was determined with respect to contact time of the impact to the surface while deflection was obtained using dial gauges of 0.01 mm accuracy. The test results of specimen showed two specimens absorbing more than 50% of impact energy. Thereby reducing the chances of fatal/major injuries by 50%. The developed material also solves the big problem of waste rubber tyre disposal in a sustainable manner. The developed material can be successfully applied various location and buildings. Hence, the developed material is green and sustainable both for humans and environment.

The mechanical properties, curing characteristics, and swelling behavior of vulcanized natural rubber (NR) blended with almond shells waste powder (ASWP) with a binary accelerator system are investigated. Results indicate that the mechanical properties were improved. Cross linking density of vulcanized natural rubber was measured by the equilibrium swelling method. As a result, the binary accelerator was found to be able to improve both cure rate and cross-linking density. Using the numerical analysis of test interaction between binary accelerator and operational modeling of vulcanization-factor experiments, it can be concluded that the interaction (Garlic oil, Cystine) was significant and the optimum value of bio-binary accelerator was suggested.

In this study, a TiO2 coating was prepared by an electrophoretic technique on 316L stainless steel. The corrosion morphology of the coating primarily included pitting, micro-cracks and NaCl attachment. The friction coefficient averages of the TiO2 coating treated at 850 °C before and after immersion in NaCl medium under different applied loads and at three slip rates are investigated. the results show that the average coefficient of friction of the coatings rises with an increase in the sliding speed and with the increase of the applied load. These results show an increase in the coefficient of friction after immersion in the NaCl solution. The value varies from 0.22 to 0.31 for a slip speed of 100 μm/s and from 0.38 to 0.51 for 300 μm/s.

An investigation was carried out on local natural cellulosic fibers which have gained interest in the composite field due to their superior specific properties. A multi scale finite element (FE) model of unidirectional natural fiber composite materials with reasonable dimensionality was developed. The mechanical behavior of the composite at macro scale as well as meso-scale was simulated. In particular the response to tensile and three-points bending test was studied. Linear material properties are obtained by using pure strains assumptions in the implicit analysis of the composite, while the non-linear behavior and viscoelastic parameters require the explicit dynamic analysis. Simulation is performed thanks to Abaqus finite element software. Comparison of Experimental and FEM tensile and three-point bending Strength shows very good agreement.

A 3D finite element modeling of the orthogonal turning process was curried out in the current study. It aims to carefully investigate the mechanisms controlling the chip segmentation and the crack propagation direction in the case of the Ti6Al4V machining. Coupled temperature-displacement numerical simulations were performed in the software Abaqus®/Explicit, under different cutting conditions. The instantaneous distribution of numerical thermomechanical variables along the width of cut was investigated. High plastic strains, temperatures and damage were predicted in the median plane of the workpiece, mainly in the shear bands around the tool tip vicinity. Whereas, a reduction of their values was noted while moving towards the chip sides and its upper surface. The 3D numerical simulations pointed out that the orthogonal machining resulted in an increase of the chip width, in addition to the material flow along the X and Y directions. The quantitative analysis of the side burr formation highlighted its sensitivity to the cutting conditions. The definition of high feed rates resulted in pronounced material flow in the workpiece edges, thus the modeling of wider chip. The present study concluded that the chip segmentation is a 3D mechanism. In addition, it pointed out the limitations of the 2D numerical simulations, as well as the inadequacy of the plain strain hypothesis, even in the case of the orthogonal machining.

This paper investigates static analysis of multilayered shells with integrated piezoelectric materials. An efficient 4-node shell element is developed to solve piezoelastic response of functionally graded structure with embedded piezoelectric actuators and sensors. A modified First order Shear Deformation Theory (FSDT) is introduced in the present method to remove the shear correction factor and improve the accuracy of transverse shear stresses. The properties of subtract material are assumed to be graded through the thickness by the power law distribution while the electric potential is assumed to be a linear function through the thickness of each active sub-layer. Accuracy and convergence of the present model is validated by comparing the numerical results with the published numerical solutions in the literature.

The aim of the present study is to predict the NiTi behavior under cyclic loading with hydrogen charging. To achieve this goal, a series of experimental tests have been carried out. First, samples have been cycled until having an imposed deformation of 2.1, 4.8, 7.6 and 8.2% till 50 cycles. Second, orthodontic specimens are submitted to cyclic loading with various strain rates of 5 × 10−3 s−1, 10−3 s−1, 5 × 10−4 s−1 and 10−4 s−1 under an imposed strain of 7.6%. Finally, arch wires are charged by hydrogen in 0.9% NaCl an aqueous solution at room temperature with a current density of 10 A/m2 for 2, 3, 4 and 6 h and are aged for 7 days in air. Throughout cyclic loading, a significant degradation of material performance is observed (the critical stress for the start and the end of the martensite transformation, the residual strain and the dissipated energy evolving). This evolution becomes more significant with a higher strain rate and with hydrogen charging rather then without it. Thus, via this work, we can assume that the embrittlement is due to the diffusion of hydrogen and the generation of dislocations after aging.

NiTi alloys have been widely used as biomaterials especially for the realization of dental devices because of their biocompatibility and superelastic behavior. However, these tools can break frequently during clinical use. The susceptibility of these alloys to cyclic loadings in the presence of hydrogen can be one of major parameters in the degradation of fatigue properties. It is admitted that the state of surface is determining to know the influence of the hydrogen in the fatigue properties. In order to study the impact of some surface treatments and the effect of hydrogen on the fatigue behavior of NiTi alloys at high number of cycles, we propose to use the self-heating method. This methodology has the advantage of being faster and cheaper than traditional fatigue tests and allows to estimate the endurance limit of the material using empirical approach. In this case, the temperature variation is considered as a relevant parameter to predict the fatigue resistance of these alloys. The results of this study showed that after a surface electropolishing treatment, the hydrogen does not affect the fatigue properties of these alloys. However, after a mechanical polishing, the effect of hydrogen is more pronounced leading to a decrease in the fatigue life of NiTi alloys with a high increasing in temperature.

The belt-finishing is a new superfinishing process which interests the industrialists in the automotive and aeronautics field. Belt-finishing is known by its ability to improve the surface topography and increase the wear resistance and the fatigue strength of the mechanical parts by inducing a strong residual compressive stress field. The aim of this work is to understand the belt-finishing process at the microscopic scale through a numerical study by ABAQUS software. This study investigates the abrasive wear mode, the influence of the scratching velocity and the variation of the friction coefficient on the residual stresses induced by a scratch test between a rigid abrasive grain and a hard steel work-piece AISI 52100. It has been shown that, for the parameters considered constant throughout the study (penetration depth h = 1 µm, attack angle of the indenter θ = 30° and the grain size D = 30 µm) the wear mode is always ploughing. Moreover, the residual compressive stresses become stronger for lower scratching velocity. Furthermore, the residual compressive stresses show significant values for lower friction coefficient. This situation favors a good mechanical resistance to fatigue of the mechanical parts.

Composite materials are the preeminent drivers for the significant enhancement to products that meet recent industrial requests. Nevertheless, their variability and the complexity of the innovative products introduce a great challenge in predicting the mechanical response fundamental for the composite design engineering. Then, to pledge a faster and more cost-effective development product, the experimental practice is switched to virtual simulation tools using advanced multi-scale analyses techniques. Indeed; developing predictive micromechanical models that enable to derive the composites’ macroscopic behavior in realistic environment based on the microscopic behavior of each constituent is obviously defiance. Therefore, to evaluate the micromechanical response of complex composite materials which are mainly nonlinear, a new micromechanical model is proposed to meticulously typify the elastoplastic behavior of composite materials and determine the optimized design. The model is developed following the composite design perspectives using a Hill-type incremental formulation and the classical J2 plasticity theory to derive the tangent operators in each phase. To assess the predictive accuracy of the estimation, the analogy to the experimental data and the exact finite element solution is proved.

This paper deals with the optical and colorometric properties of the recycled polymer during numerous internal reprocess. The effects of the number of grinding-injection cycles, three process parameters (material temperature, mold temperature, and injection rate) were investigated. One most limit for this kind of study is the large number of experiments that requires long time and significant investments. The idea is to vary five injection parameters (Tmaterial, Tmold, injection rate for five injection cycles using statistical approach. The five variables were investigated at three industrial used levels. The number of recycling varies from cycle 0 to cycle 4 at five levels. The complete matrix for screening was designed using D-optimal quadratic design. The experimental design was generated with the statistical software MODDE 10.1-Umetrics. A set of 42 experiments was carried out to determine the influence of injection parameters, polluant and recycling on the appearance properties of smooth and grained surfaces. The statistical software package Nemrodw® version 2007, LPRAI (Marseille, France) was used to analyze the experimental design.

In the field of interior ballistics, crusher gauges are still widely used for the gas peak pressure measurement within a fired ammunition. Under the effect of the gas chamber pressure, a copper cylinder deforms plastically and records its maximum amplitude. The plastic deformation is after what converted to a peak pressure through the so-called pressure/deformation conversion table which was established generally by a compression test at constant strain rate. From our point of view, this quasi-static calibration does not consider particularly the dynamic behavior of the copper crusher especially required for ballistic dynamic measurements. This might explain the difference of up to 20% in peak pressures between the crusher values and that measured by a piezoelectric pressure transducer, currently the standardized technique for pressure measurement in ballistic proof testing. The present study falls within this topic with the aim of developing a dynamic calibration method for crusher gauges. Testing was conducted through the use of the split Hopkinson pressure bars (SHPB) to investigate the mechanical behavior of the crusher gauges at different high strain rates. First of all, the stress/strain behavior was approached by a constitutive model. Then, the associated model parameter was determined through the use of the SHPB technique under different high strain rates. Finally, the pressure/deformation curve was then established through finite element modeling using Abaqus/Explicit where the gas peak chamber pressure measured by a piezoelectric transducer were taken as reference value.

The major challenge of any company nowadays is to master Quality, Cost and Delivery QCD of its products by optimizing its manufacturing process. In this context, STELIA Tunisia specialized in the aeronautical field has launched this project to improve the quality of its manufactured products in the assembly unit(Panels and frames of lower fuselage and front fuselage). Through a diagnosis, we identified the production line then the nonconformities with the highest Cost Of Poor Quality COPQ. the assembly line of lower fuselage 13–14 is concerned, more particularly nonconformity type “rejects”. Following a clear root causes analysis, we concluded that these nonconformities are mainly due to a lack of supervision, quality control and organization. Hence the need to deploy a new strategy for monitoring its processes through the implementation of process monitoring and control plans.

The countersinking process is consisted to enlarge a pre-hole using a conical punch in order to allow rivets and screws to sit flush with the surface of the assembled sheets. The geometry of the pre-hole had many effects on this process. The main goal of this study is to characterize the effects of the pre-hole geometrical parameters on the obtained countersunk hole. Their effects on the forming kinematics and the loads were investigated. A finite element model was developed using ABAQUS/Standard. The adopted model was performed with an elasto-plastic behavior and an isotropic hardening rule for the workpiece. A configuration with a maintained blank holder has been adopted for this study. The results from simulations analysis provided one good explanation for the complexity of the observed forming kinematics. The comparison between the simulations and the experimental results confirmed the validity of the adopted finite element model for predicting the loads and the final shape of the countersunk workpiece.

This work develops a meshfree method for the analysis of 3D-shell structure based on the modified first order shear deformation theory. The present meshfree method is based on the radial point interpolation method (RPIM) for the construction of the shape functions with Delta function property using arbitrarily distributed nodes in the support domains. The first order shear deformation theory is improved in this work in order to correct the constant shear strains with the Mindlin-Reissner theory and to get closer to its realistic distribution through the thickness with parabolic curves. The accuracy and convergence of the proposed model is compared to results presented in the literature.

The main objective of this work is to develop an hexahedral solid shell finite element in order to resolve the numerical locking effects that may have occurred when employing the conventional solid and shell finite elements. The developed formulation relay on the coupling between the Assumed Natural Strain (ANS) and Enhanced Assumed Strain (EAS) methods. The FE model was implemented into the user element (UEL) interface of the FE commercial code ABAQUS by using the UEL FORTRAN subroutine. The robustness and performance of this element are proven using dynamic contact metal sheet behavior at low velocity impact. The obtained results are validated with finding from the literature. The developed solid shell element is efficient from a computational view point as the thickness direction is discretized adopting only single element layer.

This paper deals with forced vibration analysis of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) plates. The equations of motion are derived using a finite element strategy which is based on a high order distribution of the displacement field. The material properties of FG-CNTRCs are assumed to be aligned in the axial direction and functionally graded in the thickness direction where uniform (UD) and three graded distributions called FG-V, FG-O and FG-X are taken into account in the analysis. The proposed method incorporates the effect of transverse shear deformations and verifies that the shear stresses vanish on the top and bottom surfaces of the structure. To illustrate the efficiency and the reliability of the present model, temporal deflections curves are provided leading hence to show the ability of the present model in the prediction of vibrational behavior of FG-CNTRC plates with good accuracy.

This chapter investigates numerically the effect of density variation on the mean and fluctuating flow properties of a turbulent rectangular jet using the Reynolds Stress Model (RSM). Two cases are tested: isothermal and heated jets. Predicted results are compared to the existing experimental data and a good agreement between them is found. Axial evolution of mean and fluctuating velocity profiles are investigated in this paper. The decrease of the jet density produces faster jet decay, leading to enhance the mixing of the gas.

With enhancements in the performance of photovoltaic solar cells, the InGaN/GaN multiple quantum wells have been considered as a very promising structure to improve the mechanism of carrier collection and hence the efficiency of conversion. The basic processes for the operation of a solar cell are the generation of electron-hole pairs, the recombination of these carriers into external circuits, and crucial step here is the generation of the electron-hole pairs. The piezoelectric charges induced by external stress generated at the InGaN and GaN interfaces induce an improvement of the electronic properties and the electrical parameters of the InGaN-MQW SC. Here, we demonstrate by a new numerical modeling self-consistent model coupled by the electrical parameters of cells, that the electronic properties and efficiency of conversion InGaN quantum wells SC have been improved by external stress. This study proves that the piezo-phototronic effect modulates the quantum photovoltaic device but also offers a great promise to maximize the use of solar energy in the current energy revolution.

The paper is devoted to numerical modelling elastic and elastoplastic problems using the Element Free Galerkin method (EFG) based on the Moving Least Square approximation (MLS). Numerical calculations are done for a number of beams and simulated using both the Finite Element Method (FEM) and the Element Free Galerkin one (EFG). Using both methods, the displacements, strains and stresses are compared. The results of this study are presented in the forms of figures and tables.

In the light of the energy crisis, energy saving has become an important topic by every country over the world. Energy consumption of buildings usually takes up to 30–40% of the human’s livelihood energy consumption. Hence, the determination of their thermal properties represents an essential task for energy computation. In this paper, a numerical approach is used in order to compute the effective thermal properties of an heterogeneous masonry structure. The structure to be studied is formed by hollow blocks with cavities filled by air, joined periodically with head and bed joints. Those hollow blocks are broadly used due to the good thermal and noise insulation. The thermal conductivities of the solid part of the hollow blocks and of the mortar are the main material input parameters. Moreover, the convection and radiation are taken into account in the cavities. The effective equivalent thermal conductivity tensor is then determined and the effect of radiation and convection is studied.

This paper describes a procedure for taking into account distributed loads in the calculation of the harmonic response of a cross-ply laminated circular cylindrical shell subjected to internal pressure using the dynamic stiffness method. Based on the first order shear deformation theory founded on love’s first approximation theory the dynamic stiffness matrix has been built from which natural frequencies are easily calculated. The vibration analysis is then validated with numerical examples to determine the performance of this model and the effect of presetress on the frequency spectrum. The response of the system is determined with applied equivalent loads on element boundaries. The described approach has many advantages compared to the finite element method, such as reducing the computing time with a minimum model size and higher precision.

In this study, numerical analysis of the static bending response of FGM is carried out with different combinaisons of geometries, boundary conditions and mechanical loading. The material properties according to the coordinates of the integration points are defined using the UMAT subroutines in ABAQUS software. The FSDT is used for thin and moderately thick FG shells analysis. The performance of the developed work is illustrated through the solution of several non trivial structure problems from literature. The numerical simulation depicts very close results to solutions in literature which assess the accuracy of the implementation. The proposed solution procedure is significantly efficient from the computational point of view.

Electric vehicles are considered as the cars of the future, given the advantages they offer compared to conventional cars, which are equipped with a combustion engine: economy of use, reliability, silence of operation, overall environmental impact, promotes the development of renewable energies and the stability of networks. However, they still have critical problems to solve as high cost, low autonomy and long charging time. The majority of these problems are totally related to the battery package. Thus, the battery package must contain enough energy to have sufficient power capacity for the accelerations and decelerations tests. Also, to have a certain driving autonomy. So, in this study, a mechatronic power system model of an electric vehicle is proposed. It is adapted to estimate the amount of energy needed to travel a certain distance. The modeling and simulation of the system were performed using the object-oriented language Modelica. While, the parametric studies for estimating energy consumption were carried using Model Center software. The developed model ensures that the performances related to the acceleration test and driving distance are respected.

About one third of the energy available on internal combustion engines is actually converted into effective power. The recovery of the dissipation heat and their conversion into electricity is an effective way to increase the efficiency of these engines and therefore reduced their consumptions. Among the current and potentially adopted technologies for this valorisation is the Organic Rankine Cycle system. Thus, the various components constituting the ORC system (motor-pump, heat exchanger and expander) were modelled and dimensioned from the parameters or data provided by the manufacturers’ catalogues, and then selected with imperative to optimize the cycle.

This paper is devoted to the numerical and theoretical study of axisymmetric variable density jet discharging into a co-flowing stream. The results reveal that k–ε models give satisfactory agreement with experimental data. The results show also that entropy generation due to mass transfer is very higher than that corresponds to fluid friction. In addition, it was found that Entropy Generation Minimization concept can be used as an indicator to evaluate mixing efficiency and mixedness.

Biomimetic robots imitating the characteristics of animals are being developed to help humans understand related phenomena in order to engineer new devices. Particularly, soft robotics are being incorporated to help imitating the natural flexibility of animals. Hence, Dielectric-Elastomer Minimum-Energy Structures (DEMES) are used to fabricate soft robots. The advantages of this solution is that the manufacturing procedure is simple. However, high voltages are required for driving them. The challenge is to use this technology at relatively lower voltages. In this research, we aim to realize Soft Underwater robots driven at low voltage to imitate the swimming of Manta. Therefore, we made a DEMES actuator usable in water by sandwiching the carbon as the electrode with two dielectric elastomers. Our robot swims faster at a lower voltage compared to the soft underwater robot that we made in a previous study.

Liquid and gas pipelines are all around us in today’s society. The frequent inspection and maintenance of such pipeline grids is very important. Recently, many pipeline inspection robot systems have been developed. In this paper, a novel in-pipe robot design is presented. The proposed design consists of two modules. The first one is the guiding module. It is formed by a driving motor and is guided along the pipe by a set of wheels moving parallel to the axis of the pipe. The second is the driving module. It is forced to follow a helical motion thanks to tilted wheels rotating around the axis of the pipe. Furthermore, the proposed design has much better mobility turning a bend due to its flexible systems supporting wheels. It has the capability to cross a bend without loses of balance and using a single drive motor. Afterwards the control of the system will be simple. Problem of robots with helical drive in the bend, new design, together with a comparative study between theoretical and simulation results will be presented as well.

In this paper, the inverse kinematic modeling of a cable driven parallel robot made out of eight cables is developed in order to control the robot’s moving platform according to a desired trajectory. An example of a Cartesian desired trajectory is fed to the kinematic model and thereby the control variables, i.e., angular position and velocity of each motor are determined. Due to the limited resources, Experiments was carried out using one motor. A comparison between the theoretical and the experimental results is given and discussed.

Considerable attention has been paid to the development of stable walking robots. Indeed, biped locomotion becomes a broadcast area where various research topics such as artificial intelligence, control theory and neuroscience cope to enhance the abilities of the robots. In this paper, Central Pattern Generator (CPG) which are neural circuits that generates oscillations for rhythmic patterns are used to control the humanoid. The choice of using a CPG as a motion generator is motivated by the naturality of the generated pattern. Moreover, CPG offers the possibility to control the gait speed ensuring an easy modulation of the walking speed. Here, the Zero Moment point is used to measure the stability of the humanoid while walking. Thus, in this paper, a humanoid robot’s walking model is presented with a strong emphasis on stability and representativity of actual human walking. Furthermore, the methodological considerations in the implementation of a CPG controller for a humanoid robot application are also presented.

This paper focus on the modeling and the designing of a reconfigurable antenaa LWA with variable capacity using MEMS-RF devices. The variable capacity MEMS can be built using an on surface micro-manufacturing in CPWG. The armatures of the MEMS–RF varactor are separated by an air gap. The choice of the materials and the adequate topology define the performance of the antenna wished in the range of frequency about 30 GHz. Simulation results of the proposed varactor are performed using the MOMENTUM tools of the ADS software. The main objective of this part is to build a variable capacity based on serial plate’s forms. The variation of the capacity is reached when the height between these plates varies. This type of varactor is in the range of pF for a frequencies band between 1 and 50 GH. A proposed Accelerometer is also analyzed, modeled and simulated denoted the distribution of the electrical flux and the power losses a function of separation distance referring to ANSYS Maxwel software.

The Anti-lock Braking System (ABS) is an active safety system for two wheeled vehicles (TWV). It is used to control the dynamics of a TWV during an emergency braking phase and to improve its driving safety. The main objective of this study is to establish a virtual model of a TWV equipped with a control scheme for an ABS system. The developed model will be used to investigate the reliability of an ABS system when used with a TWV. For this purpose, firstly a TWV multi-body dynamic model was constructed using ADAMS/View. Furthermore, a control model of the ABS system was created using MATLAB/Simulink. Then, a co-simulation approach is established using MATLAB/Simulink and ADAMS/Control. The performance of the co-simulation model is assessed by simulations for different initial speeds and for different road conditions. The obtained results show the benefits of using a co-simulation approach in studying such a complex systems. Moreover, the effects of the active safety system (ABS) on the dynamic of a TWV, during emergency braking, are studied.

The dynamic behavior of multibody systems has been widely studied. Thus, effects of imperfections such as clearance, friction and flexibility on the dynamic behaviour are dealt with various tremendous works. For a given dynamic response, the mechanism design variables needs to be defined. This identification approach is known as the mechanism synthesis. Despite all these imperfections, the mechanism should describe a precise workspace traduced by the trajectory path of the effector component. In this work, the dynamic synthesis for a multibody system with imperfections is presented. A demonstrative slider crank mechanism with a flexible connecting rod has been used for the algorithm validation. The identification approach is based on its dynamic responses such as: the slider velocity and acceleration and the transversal deflection of the flexible connecting rod. A genetic algorithm has been developed to identify its design variables. This algorithm is implemented under Matlab(c). The presented results are in great agreement with the real mechanism dimensions.

A dual technique-based inline strategy was explored in this research to enhance the conventional technique skill with regard to the limitation of wave oscillation period spreading. Instead of the single short section employed by the latter technique, the former utilizes a couple of two sub-short sections made of low density polymeric material (LDPE). Numerical computations were performed using the Method of Characteristics for the discretization of 1-D unconventional water-hammer model embedding the Vitkovsky and Kelvin-Voigt formulations. The dual technique efficiency was considered for an operating event involving the onset of cavitating flow. Results evidenced the reliability of the proposed technique for mitigating excessive hydraulic-head drop and rise, and demonstrated that the (LDPE/HDPE) plastic sub-short section combination provided an acceptable trade-off between hydraulic-head attenuation and transient wave oscillation period spreading. Ultimately, a sensitivity analysis of the wave amplitude attenuation and wave period spreading to the employed plastic sub-short sections lengths and diameters was reported to estimate the near-optimal values of the sub-short section dimensions.