The study of the stress state and power parameters when pulling workpieces in a special die with an inclined working surface at various shapes of the plastic deformation zone and geometric parameters of the special die was conducted. The distinctive feature of the proposed special die and the metal treatment process in the working channel of this die was described. The theoretical provisions and assumptions from the fundamental theory of plasticity and metal forming were used. The influence of the intensity of shear deformations on the stress state and force at the angles of inclination of the working surface of the die within 45–20°, the value of the ratio of the diameter of the workpiece to the length of the inclined surface d/z=1.5–2.0 was investigated. The optimal d/z ratio was determined by the method to a rigid punch indenting a rigid-plastic half-space, as well as by the method of strain energy. The field of slip lines and hodographs of velocities for various shapes of the deformation zone and geometric parameters of a special die were constructed. Based on the constructed slip line fields and velocity hodographs, the mean stress and stress components at the nodal points of the slip line field with the compilation of the equilibrium equations for all forces applied to the plastic zone were calculated. The study of the influence of contact friction between the working surface of the die channel and the workpiece on the stress state and power parameters during pulling was carried out. It was revealed that the optimal ratio d/z=1.5 and the optimal angle of inclination of the working channel of the die α=20°. It was found that for these parameters in the zone of plastic deformation, mainly significant compressive stresses act, which favorably affect the obtaining of a homogeneous and refined microstructure, and also exclude the appearance of anisotropy due to the implementation of maximum shear deformations in the workpiece.

In this research, crash test results from CNG locating method optimization approach for crashworthiness and testing its safety are presented. The locating process is based on principal energy considerations inspired from the current design process in passenger vehicle design development. The potential of the vehicle concept to absorb kinetic energy can be estimated at the very beginning of the design process by the free crash lengths in the different areas of the vehicle and estimates of average forces required in the specific segment and parts of the car body at particular crash phases. Based on the basic principle of vehicle crash analysis using the finite element method, a passenger VAN finite element model was selected to simulate the front and side rear collision test of the VAN, therefore the LS-DYNA software is adopted to calculate the deformation of the car and the acceleration time history curves during the crashing process; the anti-impact capability of the vehicle is evaluated from this simulation. It is important to determine appropriate force distributions and the corresponding loads paths through the whole structure for all relevant crash load in dedicated crash test cases. The results demonstrate that the improvement of local structure and location for the required CNG tanks in safe locations in vehicle chassis can promote the crashworthiness of the car, but the further improvement needs a major change of the vehicle structure. The outcomes are interpreted by using LS-PREPOST to analyze the energy absorption characteristics during crash for different cases at a velocity of 50km/h the duration of 12ms. The result analysis was necessary to derive distinct deformation phases characteristic and following that, the essential crash elements are compared with and without CNG tanks installation in each crash case. At last, the conclusion determines the proposed tank locating model in the selected passenger VAN is within the safe range of crash analysis standards.

This study applied the Constructal Design Method (CDM) associated with the Finite Element Method (FEM) through computational models to perform a geometric analysis on rectangular stiffened plates of steel subjected to a uniform transverse loading, in order to minimize its maximum and central out-of-plane deflections. Considering a non-stiffened plate as reference and maintaining the total volume of steel constant, a portion of material volume deducted from its thickness was transformed into stiffeners through the ϕ parameter, which represents the ratio between the material volume of the stiffeners and the reference plate. Adopting ϕ = 0.30, 27 geometric arrangements of stiffened plates were established, being 9 arrangements for each 3 different stiffeners' thicknesses adopted: t_s = 6.35 mm, t_s = 12.70 mm and t_s = 25.40 mm. For each ts value, the number of longitudinal (N_ls) and transverse (N_ts) stiffeners were varied from 2 to 4. Thus, in each plate arrangement configured, the influence of the ratio between the height of the transverse and longitudinal stiffeners (h_ts/h_ls) was analyzed, taking into account the values 0.50; 0.75; 1.00; 1.25; 1.50; 1.75 and 2.00, regarding to the maximum and central deflections. The results have shown that transforming a portion of steel from a non-stiffened reference plate into stiffeners can reduce the maximum and central deflections by more than 90%. Moreover, it was observed that to reduce the deflections it is more effective consider h_ts > h_ls, once the ratio hts/h_ls = 2.00 was the one that led to the better mechanical behavior among the analyzed cases.

This study presents a finite element approach of a numerical model to investigate the profile of the deformed sprayed particles and the compressive residual stresses analysis at the interfacial zone of particle and substrate impact using cold gas dynamic spray (CGDS). The Lagrangian approach was used to analyze, in details, the material deformation behavior during impact, contact problems of single-particle impact process and the outputs of equivalent plastic strain and temperature to achieve a qualitative understanding of cold gas dynamic spray contact process of cold sprayed particle on the substrate. The evolution of residual compressive stresses during impact was also analyzed for multiple-particles impact process using the Lagrangian approach. It can be observed that the compressive residual stresses increase by increasing the preheating temperature and particle initial impact velocity.

In this paper, free vibrations of the tapered shear deformable column are studied. The column is clamped at the bottom and is free or hinged or clamped at the top. The column has a tapered cross-section, square and circular, under the condition of constant volume. The axial compressive load is acted to the top. The differential equations of such column were derived, in which the effects of the rotary inertia and shear deformation were included. For computing natural frequencies with mode shapes, the differential equations were solved numerically. The effects of column parameters of the frequencies and mode shapes were performed, and its results were extensively discussed.

This work focusses on the crack growth behaviour of the compact tension specimen under mixed-mode loading, and numerical investigation using ANSYS Mechanical APDL 19.2 extended finite element software with different loading angles. The fatigue life is predicted under constant amplitude fatigue loading using the Paris’ law. The predicted values of the fatigue life in the present study provide consistency with the experimental and numerical results. In addition, the study showed that the direction of crack growth follows the same literature trend of experimental results. According to the results of the crack growth path, there is no effect of changing the geometries thicknesses on the crack growth trajectory. Its only effect is the resistance to higher plastic deformation which decreases as the thickness increases.

This work is a contribution to the study of the rigidity of rotational friction welding of cylindrical specimens made on a parallel lathe. We performed welding of three combinations of parts: steel / steel, aluminium / aluminium and steel / aluminium according to three numbers of rotations of the spindle (900, 1250 and 1800 rpm). To control the rigidity and quality of these assemblies, tensile tests are used followed by ultrasonic testing to ensure that the tips are welded and that there are no internal defects. Hardness profile of the welded zone according to the welding parameters was obtained. Metallographic observations have detected the profile of the various zones welded and affected thermally. The results of the mechanical tests showed that a rotation speed of 1250 rpm can produce a very good weld, with other parameters kept constant.

The plastic deformation behaviour of 7075 aluminium alloy during the forging process was studied using Deform 3D software. The simulation process was carried out at a constant die velocity of 5 mm/s and a varying forging temperature between 250°C and 400°C. The results showed that the forging load increased with a decrease in the forging temperature. The effective strain rate, strain and stress distribution were inhomogeneous across the deformed workpiece, indicating nonuniform forging process. It was observed that the reduction in the forging temperature during the process was responsible for the inhomogeneity. The flow curves obtained using finite element simulation code are consistent with experimental results reported in literature.

The most used approach to solve tolerance analysis problems for flexible products is the method of influence coefficients that combines the finite element analysis with statistical analysis in order to establish a relationship between the product deviation and part deviation and to foresee the statistical distribution of stresses. The key of this relationship is the sensitivity matrix for the deviations and stresses that can be evaluated by different methods of influence coefficients. Therefore, the aim of this work is to make a review of these methods applying them to evaluate on some single parts the statistical distribution of deviations and stresses due to operating conditions, i.e. due to the displacements applied to the part during its working.

The honeycomb sandwich structures are extensively utilized in the satellite load bearing structure due to their superior mechanical properties. Investigating such structures and establishing their failure map implies the estimation of their equivalent elastic parameters as well as the experimental measurements of their ultimate strengths. Through a comprehensive study, this article discusses thoroughly the mechanical behavior of an aluminum honeycomb structure exposed to flat-wise compressive and flexural testing. Furthermore, an equivalent finite element model, based upon the sandwich theory, is proposed for simulating the elastic behavior of the flexural testing and comparing computational and experimental results. The comparison of results confirms accurately the usage of the sandwich theory and its related shell-volume-shell approach in the efficient modeling of honeycomb sandwich structures. In addition, the aforementioned honeycomb structure is parameterized from the geometry and material perspective. The outcome of such study reveals that the honeycomb core thickness has the greatest influence on the maximum displacement value. In addition, aluminum alloys are optimum choice for facing sheets material of the honeycomb structure.