Use of Texture, Strain-Rate Sensitivity, and Intergranular Short-Range Effects to Calibrate the Viscoplastic Self-Consistent Model for Predicting the Forming-Limit Diagram of an Aluminum Alloy Sheet
摘要
In order to accurately predict the forming-limit diagram (FLD), texture evolution, intergranular short-range effects (SREs), and varying the slip-plane strain-rate sensitivity were used in the viscoplastic self-consistent (VPSC) model. We used these variables to control the rate of simulated texture evolution in uniaxial and balanced-biaxial tension for an AA6061-T4 aluminum sheet. Initially, we established upper and lower bounds for the simulations based on strain-rate sensitivity indices of 1/m = 20 and 1/m = 50. The simulations were then refined by accounting for short-range effects between neighboring grains. The calculated textures were compared holistically and numerically to experimental textures measured at ε11 = 0.14 in uniaxial tension and ε11 = ε22 = 0.185 for balanced-biaxial tension, thus calibrating the FLD prediction. We found that the VPSC simulation of the FLD was most sensitive to strain-rate sensitivity and whether the tangent or affine linearization scheme was used within the simulation, although the predictions using the tangent linearization were also sensitive to SREs. Our best FLD predictions were for the affine linearization and a strain-rate sensitivity of 1/m = 50. These calculations were insensitive to SREs and matched our previous experimental results. Satisfying FLD results were also found for 1/m = 50 and the tangent linearization when we used short-range effects to further calibrate the simulation based on the rate of texture evolution. This was most important on the biaxial side of the FLD.
Graphical Abstract