Within the framework of the Lagrangian approach, high-speed and hypervelocity interaction (HVI) between aluminum spherical and cylindrical particles of equal mass modeling space debris with monolithic and grid (discrete) screens is numerically investigated using the finite element method. The simulation is carried out using an author-developed 3D software complex EFES, which ensures mass conservation when fulfilling the destruction condition. The implemented destruction algorithm allows describing material fragmentation and formation of new contact boundaries without distorting the computational mesh. Evaluations have been conducted on the protective efficiency of both monolithic aluminum and discrete steel screens having identical surface density in the velocity range from 3 to 10 km/s.

The article presents results of a complex loading experiment on thin-walled brass L63 tubular specimens, demonstrating a highly non-trivial relationship between stresses and strains during elastoplastic deformation. The experimental program, as well as the interpretation and discussion of the obtained data, are based on the terminology and theoretical provisions of A.A. Ilyushin’s theory of elastoplastic processes. The experimental study was carried out in the deviatoric strain space on the automated testing machine SN-EVM under combined axial tension-compression and torsion loading of thin-walled tubular specimens. A distinctive feature of this study was the complex curvilinear strain trajectory consisting of five circles internally tangent at the coordinate origin. Each trajectory segment featured varying curvature values and circle center positions along the axis. According to A.A. Ilyushin’s definition, this trajectory qualifies as smooth since it contains no break points. During the experiment, the scalar and vector properties of the L63 brass material were studied. It was experimentally established that a change in the trajectory curvature causes a “dive” of stresses on the stress-strain diagram, which is similar to the dive that appears when there is a break angle in the trajectory, for example, in two-link broken trajectories. It was also established that the obtained experimental diagrams reflecting the vector properties of the material have a pronounced oscillatory behavior. The experimental results will be useful for verification of existing mathematical models of plasticity theory.

The true stress-true strain curves of a Mg-13Gd-3.5Y-2Zn-0.5Zr alloy were acquired by isothermal compression tests at various deformation temperatures of 350–500°C and strain rates of 0.001–1 s–1. The Johnson-Cook, strain-compensated Arrhenius-type and microstructure-based models were developed and further modified to improve a prediction accuracy. The determination coefficient and average absolute relative error were 0.9380, 10.67% for the modified Johnson-Cook model, 0.9536, 6.38% for the strain-compensated Arrhenius-type model, and 0.9813, 3.37% for the microstructure-based model, respectively. As a result, the modified Johnson-Cook model and the Arrhenius-type model could not correctly predict the high-temperature flow stress of this alloy. Meanwhile, the microstructure-based model is best suited for the prediction of high-temperature flow stress due to its very high prediction accuracy, although the calculation process is very complex. The proposed constitutive material models are of great importance in the simulation and optimization of hot working processes of Mg-13Gd-3.5Y-2Zn-0.5Zr alloys.

This paper addresses the problem of altering the natural vibration frequencies of an elastic body with embedded piezoelectric elements by applying an electric potential to them. Presented mathematical formulation of the problem based on the principle of virtual displacements for a piecewise-homogeneous electroelastic body. Finite deformations are represented as the sum of linear and nonlinear parts, which are linearized with respect to a state featuring a small deviation from the initial equilibrium position caused by the reverse piezoelectric effect. Provided experimental and numerical results validate the reliability of the numerical algorithm based on the finite element method. Using a plate with an embedded piezoelectric element as an example, presented numerical results demonstrate the influence of various parameters on the change in natural vibration frequencies: the stiffness characteristics of the elastic body; the dimensions, location, and number of piezoelectric actuators; the area ratio of the piezoelectric element to the elastic body; and the magnitude and sign of the electric potential.

Recent breakthroughs in memory-dependent and fractional-order formulations address fundamental inadequacies in classical theory. Fractional derivatives capture hereditary effects and spatial nonlocality, but memory-dependent derivatives (MDDs) allow more flexibility and interpretability by integrating kernel-defined delay mechanisms. To assist engineers and scientists in designing next-generation thermal systems, this effort aims to provide a robust and proven framework that incorporates a solid structure using memory-dependent derivatives (MDDs). Many studies have been conducted so far that have used a cylindrical-shaped structure for thermal investigations, but there is still a tremendous opportunity to modify the structural design by using a rectangular-shaped plate, which is capable and significant for the advancement of the research and is critical for contemporary design issues in infrastructure, nuclear, and aerospace engineering. This confirmed framework can only be potentially observed by creating a more precise modeling of the heat transfer equation in the light of a circular laser beam moving heat source with uniform distribution utilizing MDDs for a thin rectangular plate structure. The desired solution to the heat transfer equation (HTE) is found by applying the Laplace transformation to memory derivatives and the Fourier transform method to spatial variables. The effects of thermal stress on the plate are also assessed using the ensuing moments and forces. The temperature, deflection, and stress function results are visually shown for various time-delay parameters, kernel function options, laser-moving heat sources with varied laser powers, and scan speeds. The computing investigation examines a plate with copper-based material characteristics. Finally, the proposed mathematical modeling employing MDDs is revolutionizing heat transfer in materials exposed to laser pulses, especially in industries where precision, speed, and thermal control are critical.