基于修正M-K模型的铝合金板材成形极限图预测

为准确预测AA7075-O铝合金板材的成形极限,将韧性断裂准则和传统M-K模型相结合,提出一种基于韧性断裂准则的修正M-K模型.利用单向拉伸模拟和试验相结合的方法,提取危险单元的应力应变历史并代入C-L韧性断裂准则中,得到材料常数.基于单向拉伸试验所得成形极限点,通过MATLAB编程得到修正M-K模型的初始厚度不均度.在常温下,以单向拉伸、宽板弯曲、液压胀形试验获得AA7075-O铝合金板材的成形极限曲线,与修正M-K模型和传统M-K模型计算得到的理论成形极限曲线进行对比,验证了修正M-K模型的可行性和准确性.

Prediction of forming limit diagram of AA7075-O aluminum alloy sheet based on modified M-K model

To accurately predict the forming limit diagram of AA7075-O aluminum alloy sheet, a modified M-K model was put forward based on the ductile fracture criterion and the traditional M-K model. By using the method which combined the uniaxial tension simulation with experiment, the history of stress-strain of the dangerous element was substituted into the C-L ductile fracture criterion which was implemented into Abaqus/Explicit to get the material constant. Based on the forming limit data obtained by the uniaxial tensile, the initial thickness imperfection in the modified M-K model was obtained by the method which was programed in MATLAB. At room temperature, the experimental forming limit data of AA7075-O aluminum alloy sheet were tested through the uniaxial tensile, wide plate bending and hydraulic bulging experiments. Meanwhile, the theoretical forming limit curves obtained by the modified M-K model and the traditional M-K model were computed respectively. By comparison, the modified M-K model is proved to be feasible and more accurate.