Validation of using the elastic-perfectly plastic model to calibrate and tabulate average dynamic yield strength and loading conditions in impact-driven tamped Richtmyer-Meshkov instability experiments

[SAND 2025-00916A] In this study, the validity of using the elastic-perfectly plastic (EPP) model to evaluate the average dynamic yield strength of a material in a tamped Richtmyer-Meshkov instability (RMI) experiment is numerically investigated. The tamped RMI method is a coupled experimental and numerical technique to evaluate the dynamic strength of materials at specific pressures, temperatures, strain rates, and strains. In practice, tamped RMI experiments drive a steady shock compression wave through a corrugated interface composed of two materials with disparate densities. Vorticity generated by the propagating shock wave causes the corrugated interface to significantly deform and the extent of deformation is observed, typically through radiographic methods. Material strength is evaluated by performing numerical simulations using the EPP model, iterating yield strength until the experimentally observed deformation is reproduced. To verify and validate this approach, we apply the tamped RMI method to synthetic datasets. 400 synthetic tamped RMI datasets are generated using the Johnson-Cook, Steinberg-Guinan-Lund, Preston-Tonks Wallace, and Mechanical Threshold Stress strength models (100 each). Each synthetic dataset is then evaluated using the EPP model to evaluate the average yield strength that reproduces the synthetic dataset. The associated average pressure, temperature, strain rate, and strain loading conditions are extracted from each simulation using a variety of methods. The accuracy of the tamped RMI method is thus evaluated by comparing the EPP model strengths and associated loading conditions to the complex strength models that were used to generate the synthetic datasets. Regions of thermodynamic phase space and boundaries of material deformation in which using the EPP model is valid or invalid are determined and presented.