Experimental and numerical study for crack propagation in aluminum alloy A2024-T351

Abstract

In some catastrophic structural accidents, impact loading causes metal failure and fracture. High impact loads cause fast crack propagation, and distinct plastic deformations can be observed around the crack propagation path. The fracture behavior depends on the material ductility, loading velocity, and various other factors. Therefore, the mechanism of dynamic ductile fracture is intricately complex. This study focused on the dependence of dynamic fracture on loading velocity. Experiments were conducted for not only pure mode I fractures but also mixed mode fractures under eccentric impact loading. Fracture experiments under quasi-static loading were also conducted for comparison. The moving finite element analysis of these crack propagation phenomena was performed on the basis of the experimental observations. The numerical solutions were used for domain integration to estimate the fracture mechanics parameter. The crack propagation path was observed to depend on the loading velocity under eccentric loading. Under eccentric impact loading, the cracks did not propagate toward the loading point. The relationship among crack propagation velocity, roughness of the crack surface, and crack propagation path was also determined from these experiments. The histories of the fracture mechanics parameter during fast crack were calculated from the moving finite element analysis results. The fracture energy resistance was evaluated from the fracture mechanics parameter and was found to increase under impact loading.