Exploring the Limits of Material Strength Quantified Through Experiment and Theory

Experiments to study materials at high pressure are challenging and time consumptive, therefore we turn to modeling tools to refine and predict outcomes beforehand. Efficient models balance absolute physical accuracy against approximate but computationally lightweight constitutive inputs. By using a relatively small number of high-fidelity simulations and experiments we have been able to broaden the predictive power of the shock response in metals and polymers. We have tailored the analysis of these simulations to determine a size dependent material strength, which can be used as constitutive model inputs for continuum hydrodynamics codes. Simulations of shocked Cu utilizing Molecular Dynamics(MD) simulations show a yield strength from Richtmeyer-Meshkov Instability(RMI) jet growth of approximately 450MPa that depends on the details of the free surface geometry. This is in agreement with our experiments at the Dynamic Compression Sector where an elastic-perfectly-plastic strength model was parameterized from phase-contrast imaging of the RMI jetting. The same analysis applied to MD simulations of PMMA jetting resulted in no clear determination of yield strength, implying a more complex RMI process in polymeric materials.