基于GTN细观损伤模型的激光拼焊板成形极限预测

建立了从细观损伤角度预测拼焊板成形极限的Gurson-Tvergaard-Needleman(GTN)损伤模型,用有限元逆向法确定了损伤模型中的各损伤参数。采用有限元软件ABAQUS耦合基于Mises屈服准则的弹塑性GTN损伤模型,对拼焊板半球凸模胀形过程进行了数值模拟。设计了拼焊板半球凸模胀形物理试验,试验过程中通过改变试件的宽度得到了不同应变状态下完整的拼焊板成形极限图,并与GTN细观损伤模型预测到的拼焊板成形极限图进行对比分析,验证了GTN细观损伤模型预测拼焊板成形极限图的准确性。

电池壳钢韧性断裂与成形极限研究

针对电池壳钢的韧性断裂与成形极限问题,通过单向拉伸试验获得了材料的基本力学性能,设计了不同形状规格与应力状态的断裂试样,采用半球凸模胀形和缺口拉伸两种试验方案,结合模拟仿真求解了各试样的断裂相关状态变量,利用曲面拟合法识别了MMC、DF2015和Hu这3种韧性断裂准则的控制参数,然后构建了基于多种变量空间的断裂曲面进行对比分析。结果表明,半球凸模胀形试验确定的断裂应变高于缺口拉伸试验。此外,基于半球凸模胀形试验标定的DF2015模型预测的各种应力状态试样的断裂位移更接近试验值。

Theoretical prediction and experimental investigation on formability of tailor-welded blanks

Based on the elastoplastic mechanical properties of the weld and heat affected zone metals obtained by a nanoindentation test, a theoretical calculation model was established for the forming limit diagram（FLD） of tailor-welded blanks（TWBs） on the basis of plastic constitutive relations and Hosford yield criteria. Hemispherical punch bulging tests were performed to verify the FLD theoretical calculation results. The results demonstrated that not only the FLD theoretical calculation of base materials but also that of TWBs had a good agreement with their experiments. Besides, poorer formability of TWBs caused its FLD significantly lower than that of base materials. The theoretical calculation model offers a reliable approach to obtain the specific FLD of TWBs.