有效的板料成形反向模拟法应力修正策略

金属在流经凹模圆角时受到强烈的弯曲作用,传统的板料成形反向模拟法没有考虑变形历史对应力预测的影响,使得反向模拟法计算的应力值与实际情况有较大偏差.针对反向模拟法无法准确预测成形零件应力分布的缺点,提出一种快速搜索流经凹模圆角区域的单元的方法,对该部分单元进行应力修正.采用一种高效的单轴连续拉伸应力应变本构关系模型,避免了增量有限元法应力应变更新算法的复杂性,同时充分考虑了凹模圆角对金属变形历史的影响.NUMISHEET'93盒形件拉深的标准考题中,通过与增量有限元模拟软件DYNAFORM计算结果的比较,验证了采用提出的多步连续拉伸本构关系模型可以有效地反映变形历史的影响,获得更加接近实际的应力分布.

Efficient Strategy for Stress Distritution in Inverse Analysis of Sheet Metal Stamping

To overcome shortcomings of traditional inverse analysis method(TIAM),a fast and reliable searching scheme is used to find elements passing through die entrance radius during deformation process.An efficient stress-strain relation for continuous uniaxial tensile test is introduced to update stress distributions. Constitutive equations avoid complexity of incremental FEM based stress/strain updating algorithms,and effects of die entrance radius on deformation history are considered.Numisheet'93 square box drawing benchmark demonstrates that the constitutive equations significantly enhance prediction of stress distribution compared with incremental FEM based software DYNAFORM.