Determination of flow stress of magnesium alloy sheet AZ31B by reverse analysis method

Abstract

The reverse analysis method is presented to determine the flow stress of magnesium alloy sheet AZ31B based on limiting dome height tests. The determination of flow stress is treated as an optimization problem by the reverse analysis technique. The unknown coefficients in the flow stress equation are regarded as design variables, and the difference between experimental loads and corresponding predictions by the finite-element method is calculated as an objective function. The response surface method is used to solve this optimization problem, and the flow stress of the material is determined by optimal values of design variables. In this study, the flow stress of an AZ31B sheet is determined at 250°C by reverse analysis. The limiting dome height tests for AZ31B sheet are carried out and sampling points are chosen from load against stroke curve. The finite-element analysis model for the sheet forming according to the test condition is set up. The numerical simulations are performed with sample values of design variables and objective functions are calculated. The response surface equation is formulated by the regression analysis and the optimal values of design variables are obtained by minimizing the equation.