Dynamic Fracture of Aluminum Bonded Composites

Abstract

A dislocation densitybased crystal plasticity framework, a nonlinear computational finiteelement methodology adapted for nucleation of crack on cleavage planes, and rational crystallographic orientation relations were used to predict the failure modes associated with the high strain rate behavior of aluminumbonded composites. A bonded aluminum composite, suitable for high strainrate damage resistance application, was modeled with different microstructures representing precipitates, dispersed particles, and grain boundary (GB) distributions. The dynamic fracture approach is used to investigate crack nucleation and growth as a function of the different microstructural characteristics of each alloy in bonded composites with and without preexisting cracks. The nonplanar and irregular nature of the crack paths were mainly due to the microstructural features, such as precipitates and dispersed particles distributions and orientations, ahead of the crack front. The evolution of dislocation density and the subsequent formation of localized plastic slip contributed to the blunting of the propagating crack(s). Extensive geometrical and thermal softening resulted in localized plastic slip and had a significant effect on crack path orientations and directions along cleavage planes.