For rigid-perfect plastic solids, ideal plastic flow happens when all material elements follow minimum work paths and the two principal stretch lines are materially embedded. To describe its kinematics effectively, Lagrange convective orthogonal curvilinear system has to be constructed. Therefore, a numerical procedure for generating orthogonal body-fitted meshes has been developed and applied to non-steady plane-strain ideal plastic flow. The mapping between the Cartesian system and the orthogonal system is based on Laplace equations and Cauchy–Riemann condition. The numerical procedure takes into consideration of all the prescribed boundary curves instead of one as the boundary conditions, which has been adopted in earlier studies when using conventional characteristic line method. After each iteration step, the obtained boundary points are adjusted towards the orthogonality conditions until error tolerance requirement is met. For demonstration purpose, the numerical procedure is applied to the optimization of a bulk part under forging. The obtained orthogonal body-fitted meshes are in good agreement with previous methods. Then the optimal initial scale factor is also calculated based on this method and compared with earlier studies. Finally, the evolution of the intermediate shapes and frictional external boundary conditions is also calculated when there are no elastic dead zones.

对于刚性完美的塑料固体，当所有材料元素都遵循最小工作路径且两条主要拉伸线均已嵌入材料时，便会产生理想的塑料流动。为了有效地描述其运动学，必须构造拉格朗日对流正交曲线系统。因此，已经开发了一种用于生成正交拟合网格的数值程序，并将其应用于非稳态平面应变理想塑性流。笛卡尔系统和正交系统之间的映射基于拉普拉斯方程和柯西-黎曼条件。数值程序考虑了所有规定的边界曲线，而不是考虑一条边界条件，这是在早期研究中使用常规特征线法时已经采用的。在每个迭代步骤之后，将获得的边界点调整到正交条件，直到满足容错要求。出于演示目的，将数值过程应用于锻造下的散装零件的优化。所获得的正交拟合人体网格与以前的方法非常吻合。然后，基于此方法还可以计算出最佳的初始比例因子，并将其与早期研究进行比较。最后，当没有弹性死区时，也可以计算中间形状和摩擦外部边界条件的演变。所获得的正交拟合人体网格与以前的方法非常吻合。然后，基于此方法还可以计算出最佳的初始比例因子，并将其与早期研究进行比较。最后，当没有弹性死区时，也可以计算中间形状和摩擦外部边界条件的演变。所获得的正交拟合人体网格与以前的方法非常吻合。然后，基于此方法还可以计算出最佳的初始比例因子，并将其与早期研究进行比较。最后，当没有弹性死区时，也可以计算中间形状和摩擦外部边界条件的演变。