预紧力作用的复合材料-金属螺栓连接结构 ① 承载与损伤行为研究

An improved 3D assembly model of composite-metal bolt joint with a refined thread structure was established to investigate the influence of different preloads on the tensile mechanical performance of the structures. Elastic-plastic deformation theory was used to define the behavior of metallic materials in the joint structure. Hashin failure criterion and the bilinear cohesive zone model were used to describe the damage of each component within the ply and the interlaminar damage, respectively. The reliability of the numerical model was verified by the preparation of standardized samples and subsequent tests. The results show that the numerical model can accurately capture the tensile stiffness and peak load of bolt joint structure and the material damage. There is a nonlinear critical effect of the tightening torque, and the critical torque of the bolt is 4.0 N·m, corresponding to the peak load of 487.27 MPa, and the load-bearing performance is significantly weakened by the concentration of stress around the holes when the critical value is exceeded. The failure of composite joint is dominated by matrix cracking and interlaminar delamination, the plastic deformation of metal joint is concentrated in the contact area between the hole perimeter and the bolt, and the plastic deformation of the bolt is concentrated in the root of the thread and the engaging part.