THE DEVELOPMENT OF STRESS BASED CONTINUUM DAMAGE MECHANICS MODEL FOR PREDICTING THE FORMABILITY OF MAGNESIUM ALLOYS UNDER COLD/WARM STAMPING PROCESSES

Abstract

This paper presents the development and application of the novel 2D-stress based continuum damage mechanics (CDM) model for prediction of the formability of magnesium alloys under cold/warm stamping conditions. The CDM model is divided into parts; firstly, a set of uniaxial viscoplastic damage constitutive equations is determined from tensile data. Secondly, a set of multiaxial viscoplastic damage constitutive equations is formulated and calibrated from the forming limit diagram (FLD) data. The experimental uniaxial tensile data for AZ31B magnesium alloy (at different deformation conditions (temperature range of 20°C to 300°C and strain rate range of 0.001 and 0.01s-1) and FLD at the temperature of 250°C were published by Wang et al., [1] and were used to formulate and calibrate the CDM model. A good agreement has been achieved between the experimental and numerical data. Using the newly developed plane-stress unified viscoplastic damage constitutive equations, the FLD of materials can be predicted at different temperatures and strain rates with complex strain path forming conditions.