Dynamic constitutive model and finite element simulation of impact loading of 6008 aluminum alloy based on precipitation hardening and damage

Abstract

Dynamic and microscopic impact experiments were conducted to investigate the mechanical properties and constitutive relationships of a 6008 aluminum alloy under dynamic impact loading. The micromechanical responses and plastic deformation of the alloy under high-strain-rate loading were analyzed. As the loading strain rate increased, the grains became finer, and the dislocation density and number of dimples increased. The interactions between the precipitated phases and dislocations can be categorized into bypassing and shearing mechanisms, which impede the motion of dislocations and increase the flow stress in the material. The precipitated phases affected the propagation of microcracks and changed the toughness of the material. A dynamic constitutive model for the behavior of the material under impact compression loading was developed based on the evolution of dislocation density and precipitation hardening. A Gurson-Tvergaard-Needleman damage model was combined with the constitutive model for behavior under dynamic impact compressive loading to obtain a constitutive model for the behavior of the material under dynamic impact tensile loading. The VUMAT subroutine was used in the model. The results of the finite element simulation of the behavior of the material implemented using the dynamic impact tensile loading constitutive model agreed well with the experimental results, confirming the suitability of the model. In this study, we examined the macromechanical response, microstructure, and dynamic mechanical behavior of 6008 aluminum alloy under dynamic impact conditions to establish a theoretical basis for the structural design and safety evaluation of high-speed trains.