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.

This paper focuses on the application of foamed bitumen technology in the production of asphalt mixtures. This technology replaces the common asphalt binder with foamed bitumen for production of asphalt mixtures. Given the foaming, it is possible to produce asphalt mixture at a lower working temperature. This “eco-friendly” technology has been increasingly used by the asphalt mixture producers in Europe because of reducing the energy demands of the asphalt mixture productions. In this paper, first the technology of the foamed bitumen production is explained and then the results of laboratory research are presented, in which selected empirical and functional parameters of two types of asphalt mixtures of the asphalt concrete type (AC) are compared. These mixtures were produced in two versions, one of them containing the common asphalt binder and the other one the foamed bitumen. While comparing the samples, attention was paid especially to the comparison of the stiffness modulus of the laboratory-produced asphalt mixtures according to EN 12697-26 and to their low-temperature characteristics according to EN 12697-46.

The numerical simulation of fatigue behavior of the Aluminum 7075-T6 cantilever beam with an angular crack has been investigated. Cracks are located separately in three different positions of the investigated beam. To predict the fatigue behavior of the cantilever beam the crack propagation was manually simulated. Compression load is applied in different stress ratios between zero and one; then, the obtained numerical results of this research are compared with the experimental results. It is observed that increasing the stress ratio increases the percentage of the fatigue life of the sample significantly. Ascending growth of fatigue life is slow and more severe by increasing of the stress ratio for the first and the third position, respectively. By increasing the stress ratio, the rate of deviation of the crack decreases and it converges to 0° in parallel to the width of the beam. This result is also observed with an increase in the distance from the support of beam. Furthermore, it is also revealed that by the increase in the initial length of the crack, the fatigue life initially reduces with smaller ratios. However, along the larger cracks, the decreasing ratio of fatigue life increases significantly.

In this paper, economic analysis on the effect of polyester fibers with high strength on the behavior of Hot Mix Asphalt (HMA) is performed. The results indicate that strength is increased by adding fiber to asphalt. Also, unit weight of asphalt mixture was used as a variable parameter in the analyses. The results show that in some certain percentages of fiber, in addition to the enhancement in mechanical properties of HMA mixture the economic benefit value becomes more than the cost and therefore adding polyester fibers with high stability is suggested for the mixture of modified asphalt concrete. Finally, it can be concluded that adding fibers in values of 0.2% to 0.5% has the best result on the asphalt mixture, which because of high resistance and economic aspects makes it more efficient to be used in the highways of warm regions containing traffic.