应力-应变曲线形式对铝合金板料成形极限的影响

Effect of Data Mode from Stress-Strain Curve on Forming Limit of Aluminum Alloy Sheets

为使板料的成形性分析更符合实际,以Marciniak-Kuczynski(M-K)理论为基础,提出了采用应力-应变测量数据预测铝合金板料成形极限的方法.分别采用应力-应变测量数据、幂指数以及多项式拟合曲线三种应力-应变形式对6016-T4和7075-T6铝合金板料的成形极限进行研究.通过单向拉伸实验得到材料的应力-应变数据,构建了不同形式的曲线模型,计算了相应的极限应变,并绘制了板料成形极限曲线.将理论上预测的FLC与胀形实验结果进行对比,结果表明,采用应力-应变测量数据对板料成形极限的预测最好,而常用的幂指数拟合曲线得到的预测结果与实验存在一定的偏差.

In order to analyze sheet formability more realistically,a new approach based on the M-K theory was proposed,which predicted the forming limit of aluminum alloy sheets by using different modes of data from the measured stress-strain curve.The forming limits of 6016-T4 and7075-T6 aluminum alloy sheets were theoretically analyzed using three modes of data,which were the original data of the measured stress-strain curve,the power exponential fitted data and polynomial fitted data of the stress-strain curves,respectively.According to the stress-strain data from tensile test,the ultimate strains were calculated and the theoretical forming limit curves(FLC)were plotted.After comparing the theoretically predicted FLC with experimental data from the bulging test,the results indicate that the predicted forming limits using the data of the original stress-strain curve is the best one,while the forming limits using the data from the power exponential fitted curve has a certain deviation from the experimental one.