基于接触约束边界条件的加工变形预测方法

Machining Deformation Prediction Method Based on Contact Constraint Boundary Condition

有限元仿真被广泛应用于航空薄壁结构件加工变形的预测分析,针对现有3-2-1约束原则建立仿真边界条件时存在众多的问题,提出了接触单元约束边界条件法(接触边界法)。基于接触边界法建立有限元预测模型,并引入实测初始残余应力对工件加工变形进行了仿真预测。为验证接触边界法的准确性,选取工件展开了铣削加工及变形测量实验,结果表明仿真与实验变形在变化趋势及变形值上均具有很好的一致性,从而验证了接触边界法的可靠性。利用接触边界法建立的有限元模型对加工后的工件残余应力场进行预测,结果表明:通过变形和残余应力重分布会使加工后工件内部残余应力场达到新的平衡;对于薄壁结构件,材料大量去除后,残余应力值明显减小。

Finite element simulation is widely used in the machining deformation prediction and analysis of aerospace thin- walled components. Aiming at numerous defects when building simulation boundary conditions through using existing the 3 -2 - 1 principle, a contact element constraint boundary condition method was proposed （CBM）. In addition, a finite element model （FEM） of machining deformation was established based on CBM and the model was used to predict the deformation through considering the actual initial residual stress. To validate the accuracy of CBM, the deformation was measured through experiments. The results show that the prediction is in good agreement with the experimental deformation in the change trend and deformation values, which verifies the reliability of CBM. Finally, the residual stress field of the workpiece was predicted using the FEM. The results show that the residual stress field in the workpiece can reach a new equilibrium by the deformation and residual stress distribution. For the thin -walled structure, the residual stress value is significantly reduced after the material is removed.