Computational comparisons of homogeneous and statistical descriptions of AerMet100 steel subjected to high strain rate loading

Abstract

In order to simulate the effect of material microstructure a statistically compensated Johnson-Cook (JC) fracture model has been implemented into the Eulerian shock physics code, CTH. This model uses a Weibull function to produce a distribution of initial failure strains within the JC fracture model. A parametric analysis where the Weibull modulus was systematically varied was conducted on two sets of experimental fragmentation data. The first experiment consisted of an explosively loaded cylinder of AerMet100. The second was an expanding tube experiment which used a plastic cylinder to load the AerMet100 and provided a problem at a lower strain rate. In both sets of experiments, the fragments were soft captured for later examination. While CTH does not explicitly track fragments, a post processor written at the Naval Surface Warfare Center Dahlgren Division was used to calculate the mass of each of the fragments in the expanding debris cloud. The results were analyzed and compared back to baseline homogeneous calculations. The use of a statistically compensated JC fracture model substantially improved the fragment mass distribution for the explosively loaded cylinder. However, the lower strain rate expanding tube showed only minimal improvement. A probable reason for this limitation and future analysis are discussed.