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考虑到一步反向模拟法无法考虑变形历史的影响、无法计算各中间步之间的应变等信息,文章提出一种新型的多步反向模拟法。根据当前工步凸凹模信息,采用最小面积法,并结合可行域二次序列规划算法(FSQP)快速获取当前工步零件的构型。提出一种基于重心坐标的穿越搜索策略来提高接触搜索速度,计算复杂度仅为O(n1/d)(d为网格所在空间的维数)。提出的快速接触搜索算法来实现中间构型各个节点在约束滑移面上的移动,其理论成果成功地在自行开发的板料成形反向模拟法软件InverStamp/Multi-step模块中实现。在圆筒形件多步拉深实例中,通过中间工序及最终成形零件厚度分布与基于增量理论的LS-DYNA求解器计算结果的比较,验证了多步反向模拟法的有效性。
Considering that the one-step backward simulation method can not consider the influence of deformation history and can not calculate the information of strain between intermediate steps, a new multi-step reverse simulation method is proposed. According to the information of the convex and concave molds of the current step, the minimum area method is used, and the FSQP algorithm is used to quickly obtain the current configuration of the step parts. A crossing search strategy based on barycentric coordinates is proposed to improve the contact search speed. The computational complexity is only O (n1 / d) (d is the dimension of the space where the grid is located). The fast contact search algorithm is proposed to realize the movement of the nodes in the intermediate configuration on the constrained slip surface. The theoretical results have been successfully implemented in the InverStamp / Multi-step module of sheet metal forming inverse simulation software developed by ourselves. In the case of cylindrical multi-step drawing, the effectiveness of the multi-step inverse simulation is verified by comparison of the calculation results of the LS-DYNA solver with the incremental theory and the intermediate step and the final thickness distribution of the formed part.