Crystal Plastic Finite Element Analysis of Dynamic Compression of Aluminum Alloy Considering Dislocation Density

Abstract

Macroscopic mechanical response and microstructure evolution of 7075-T6 aluminum alloy during dynamic compression were investigated by experiments and crystal plastic finite element method (CPFEM). The dynamic compression experiment of 7075-T6 aluminum alloy with a strain rate of 2 000 s-1 was carried out with a split Hopkinson pressure bar (SHPB). The microstructure of aluminum before and after dynamic compression was characterized by electron backscattering diffraction technique (EBSD). The internal state variables of dislocation density were introduced into the CPFEM model by modifying the strengthening model and the flow criterion. The effects of friction coefficient, dislocation multiplication coefficient, and dislocation annihilation coefficient on the macro mechanical properties of the specimens were investigated. The results show that the increase of dislocation multiplication coefficient aggravates the hardening behavior and increases the ultimate strength of the material, and the increase of dislocation annihilation coefficient reduces the ultimate strength of the material while weakens its hardening behavior. Through the comparison of experimental and simulation results, it could be seen that CPFEM accurately predicts the variation trend of the texture during dynamic compression, as more brass {110} texture and Goss {110} texture are generated.

Keywords

• crystal plastic
• dislocation density
• texture
• dynamic compress
• aluminum alloy