Large Strain Cyclic Simple Shear Behavior of Aluminum Extrusions: An Experimental and Numerical Study

It has been shown that dislocation cells induce intragranular backstresses due to blockage of dislocation passage. The present work focuses on the effects of dislocation induced backstresses on the strain hardening behavior of AA 6063-T6 extruded aluminum alloy during cyclic planar simple shear deformation. Based on the previous work of Brahme et al. [1], the internal stresses are predicted using a close form solution based on the Eshelby’s inclusion problem. Using this approach the inherent dislocation microstructure is modeled as a two-phase material consisting of highly dense harder cell walls and less dense soft cell interiors. The new formulation also takes into account the evolution of dislocation cell structure with plastic deformation. Simulations are performed for simple shear and the predictions are compared against experimentally obtained flow stresses for forward, reverse and subsequent forward in-plane simple shearing.