Experimental and computational investigation of the dynamic behavior of Al-Cu-Li alloys

A dislocation-density based crystalline plasticity formulation, finite-element techniques, rational crystallographic orientation relations and a new fracture methodology were used to predict the failure modes associated with the high strain rate behavior of high strength Al-Cu-Li alloys. Widely used aluminum alloy 2195 (AA2195) was taken as the representative of Al-Cu-Li alloys. Experimental characterization using Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) were performed to gain insights on microstructural behavior. The alloy aggregate was modeled with representative microstructures that included precipitates, dispersed particles, and different grain boundary (GB) distributions. The new fracture methodology, based on overlapping elements and phantom nodes, was used with a fracture criteria specialized for fracture on different cleavage planes to investigate dynamic crack nucleation and growth. The compressive behavior of AA2195 under high strain rate loading was compared with that of Al-Cu alloy 2139 to further understand the behavior of the AA2195 with the more ductile AA2139. The predictions quantify how local microstructural effects, due to precipitates and dispersed particles, have a dominant effect on crack initiation and growth.