基于三维多相有限元的CFRP细观切削机理研究

为深入揭示碳纤维增强树脂基复合材料(Carbon fiber reinforced plastic/polymer,CFRP)切削机理,针对目前宏观单相有限元方法无法直观体现纤维和基体的失效形式、切屑类型等问题,借助数值仿真方法建立了CFRP直角切削的三维多相有限元模型。测量刀具刀尖形貌,根据刀具和CFRP设计数据提取CFRP纤维、基体细观几何信息,建立直角切削细观几何模型;基于定义材料本构用户子程序(User subroutine to define material behavior,VUMAT)分别定义纤维和基体的材料本构(弹塑性、失效准则、损伤演化方式),对不同纤维方向角的三维多相CFRP直角切削模型进行仿真分析;设计直角切削试验对仿真结果进行对比验证。仿真结果直观地展示了基体和纤维的失效形式、切屑形成过程、不同情况下切削亚表面损伤深度,通过各种情况下切削力数据的分析,揭示了切削力随纤维方向角的变化规律,并通过试验验证了该有限元建模仿真方法的有效性。

Research on the Mesoscopic Cutting Mechanism of CFRP Based on Three-dimensional Multiphase Finite Element Models

As the single-phase macroscopic finite element method has some shortages in presenting the failure model and the chip formation of the fiber and matrix, several three-dimensional multiphase finite element models are established to simulate the orthogonal cutting behavior of carbon fiber reinforced plastic/polymer (CFRP) and acquire a more in-depth understanding of the .cutting mechanism of CFRP. First of all, the tool nose is scanned and measured, and the geometric models are set up according to the geometric information of the fiber, the matrix and the tool. Secondly, the constitutive relationship, involving elastic-plastic relationship, failure criterion and damage evolution, is described by VUMAT and various CFRP cutting simulations with different fiber orientations are conducted. The results of the simulations are verified by the orthogonal cutting experiments. The failure model, the chip formation and the sub-surface damage in different cutting situations are displayed visually. The relationship between fiber orientation and cutting forces is revealed by the outputted data of different cutting situations, and the finite element models are validated by the experimental results.