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Based on the shock-loading technique of a two-stage light gas gun, the yield strength of copper was measured by the shock wavefront disturbance method for the first time. Additionally, based on Steinberg–Cochran–Guinan constitutive model, a numerical simulation procedure for the evolution of perturbed shock front in copper was first constructed. Combining numerical simulation results with experimental results, the yield strength of copper was found to be $0.72\pm 0.01$, $0.99\pm 0.02$, $1.31\pm 0.02$, $1.65\pm 0.03$ and $1.82\pm 0.02$GPa at pressures of 47.17, 60.67, 76.98, 101.35 and 124.26GPa, respectively. The results were in good agreement with those obtained by the AC method. According to the phase diagram of copper, there was no phase transition under experimental shock-loading pressure, and the yield strength of copper increased with increasing shock-loading pressure. Research on the yield strength of copper under shock loading was of great significance to various fields.

Sandwich panels can be manufactured in many ways like lamination press, closed mold fabrication, and vacuum bag compaction. During manufacturing, the core and the sheets are attached under certain applied pressure and temperature, associated with a deformation and stress remaining in the sandwich core. This study presents an evaluation of the compressive residual stress effect of the core which occurs during the localized shock loading at the mid-span of a clamped sandwich plate. We simulate such a square lattice core sandwich plate by commercial finite element code, ABAQUS/Explicit. We apply uniform distributed loading on upper face sheet and temperature difference occurred during the manufacturing process is taken here before the impact simulation step. These loadings induce certain amount of residual stresses in core structure of sandwich panel. The computational result from non-residual stress case is verified by comparing with the results of published experimental data on similar investigation. In addition, the effect of existing residual stress at core is analyzed. We also compare the dynamic responses of two clamped sandwich plates with and without pre-stressed core. And impact resistance of sandwich panel is explained in the view of energy capacity. Results show that the shock loading behavior of sandwich panel depends on its manufacturing process and panels with compressive residual stresses have less deformation and high impact energy absorption characteristics.

In general, a system deteriorates due to internal physical degradation and external random shocks. Previous studies mainly focused on establishing dependent competing risk models to evaluate mutual effects of degradation processes and random shocks affecting system health. However, there is a lack of consideration about the magnitude of impacts caused by random shocks on degradation processes. Thus, a shock-loading-based degradation model is proposed to classify the magnitude of impacts from random shocks on degradation processes based on the threshold of the cumulative shock loading. Copula methods are utilized to derive joint reliability function from multiple marginal distributions of degradation processes. Two numerical examples are utilized to demonstrate the reliability prediction performance of the proposed model. First, a simulated example is used. The second example employs the turbofan engine degradation data from the NASA Prognostic Data Repository to show the performance of the proposed shock-loading-based degradation process and its corresponding system reliability model.