Finite-Element Damage Analysis for Failure Prediction of Warm Hydroforming Tubular Magnesium Alloy Sheets

摘要

Bursting has been recognized by many researchers as a common failure mode in the tube hydroforming (THF) process. Therefore, the prediction of the bursting that occurs during the THF process has received much attention in the manufacturing industry and research institutions. Effective prediction of failure can reduce significantly the number of practical trials required to obtain the desired products. However, the prediction of such bursting for magnesium-based (Mg-based) alloy can be a rather difficult issue due to the nonlinear nature of the model used to describe the deformation process at elevated temperatures. This article proposes the failure prediction of Mg-based alloy during the THF process at elevated temperatures by using the Marciniak and Kuczynski (M-K) model. In the study, numerical simulation was performed by the finite-element (FE) analysis commercial software ABAQUS, with the material model assumed to be elastic-plastic. The constitutive model of Mg-based alloy (AZ31B) tube at different elevated temperatures, for instance at 493 K, 523 K, and 553 K, was represented by the Fields-Backofen constitutive equation, with material parameters collected from relevant literature. Accordingly, THF experiments were conducted by a self-developed thermal hydroforming attachment coping with an existing hydraulic power press to validate the prediction of the numerical results. The geometrical parameters for the specimen tubes used in the experiment were 22 x 150 mm, and 1.5 mm wall thickness. The numerical and the experimental results were demonstrated to have good agreement. The results of the simulation and the THF experiments imply that the model proposed in this study can provide a reliable prediction of the failure analysis of the Mg-based alloy tube during the THF process.