基于XFEM-CZM耦合法的胶接接头裂纹扩展分析及强度预测

采用扩展有限元法（XFEM）和内聚力模型（CZM）相耦合的方法，分析胶接接头胶层内部裂纹扩展、界面脱粘分层现象。采用内聚力单元和内聚力接触描述胶层/板材界面，建立单/双搭接接头有限元模型。预测拉伸载荷下接头的强度性能并与已有试验数据对比分析，验证XFEM-CZM耦合法的可行性及内聚力单元和内聚力接触2种界面建模方法的有效性。模拟裂纹从胶层内部扩展至胶层/板材界面并引起界面脱粘分层的过程，分析其损伤失效机理。讨论初始裂纹长度和界面刚度、强度及应变能释放率对胶接接头强度性能的影响。结果表明:胶接接头强度随初始裂纹长度增加而降低，且在双搭接接头模型中表现更为明显；界面刚度、强度对胶接接头强度影响较大而应变能释放率的影响较小。 

Crack propagation analysis and strength prediction of bonded joints based on XFEM-CZM coupling method

In this paper, the crack propagation and interface debonding in the adhesive layer of bonded joints were analyzed based on the coupling method of Extended Finite Element Method (XFEM) and Cohesive Zone Model (CZM). By using the cohesive interfacial element and surface-based cohesive contact to describe the interface between adhesive layer and adherent, the finite element models of single- and double-lap joints were established. The strength properties of bonded joints under tensile loading were predicted and compared with available experiment data. The feasibility of XFEM-CZM coupling method and the effectiveness of cohesive element and cohesive contact interfacial modeling methods were verified. The process of crack propagation from the interior of the adhesive layer to the adhesive layer/adherent interface was simulated, and the damage and failure mechanism in this process was analyzed. The effects of initial crack length, interface stiffness, strength and strain energy release rate on the strength properties of bonded joints were discussed. The numerical results show that the strength of bonded joints decreases with the increase of initial crack length, and it is more obvious in the double-lap joint model. The interface stiffness and strength have greater influence on the strength of bonded joints while the effect of strain energy release rate is small.