自定义粘接元接触技术在复合材料连接强度分析中的应用
Application of contact technology based on the user-defined cohesive element in the strength analysis of composite fastened joint
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摘要: 为解决复合材料接头强度分析中由于接触造成的收敛困难问题, 自定义了具有特殊本构关系的粘接元用来模拟接触, 该单元只能传递压力而不能传递拉力。自定义的粘接元被置于两接触对之间用来传递接触压力, 从而保证了接触体之间在接触面上的变形协调关系。同时, 建立了复合材料单钉接头的三维累积损伤有限元模型。基于文献中材料性能退化模型, 对纤维及基体压缩破坏的刚度退化模式做了改进, 并利用自定义粘接元接触技术及改进后的刚度退化方法对模型进行了有限元模拟。最后对四组相应试验件进行了试验验证, 试验结果和模拟结果吻合较好, 证明了自定义粘接元接触技术以及文中模型和算法的有效性。Abstract: In order to solve the convergence difficulties caused by contaction in the analysis of composite bolted joints, the user-defined cohesive element with special constitutive behavior was developed to model contaction. This element could only transfer the pressure, but not the tension. The user-defined cohesive element was placed between the two interfaces in order to transfer the contact pressure, so that it becomes a way to guarantee the relation of coordination between the deformation of the two interfaces. Meanwhile, a three-dimensional progressive damage model was developed to model composite laminates with a single bolted joint. The stiffness reduction associated with damage due to compressive loads was improved based on the method of the document. The contact technology based on the user-defined cohesive element and the improved method of the stiffness reduction were used to predict strength of the model. At last, experimental results concerning the bearing strength were obtained and compared with the predictions, from which a good agreement was observed.