Dynamic Characteristics Analysis of Connection Structure of C/SiC Ceramic Matrix Composites

The hot end components of aerospace vehicles cannot be completely machined into an integrated structure, so a large number of C/SiC Ceramic matrix composite connection structures are used. The connection structure of C/SiC composite materials has the characteristics of low pre-tightening force and the need for secondary deposition during the preparation process. Its tightening mechanism is different from that of metal fasteners, which makes it difficult to analyze the dynamic characteristics of the connection structure. In this paper, the Tensile testing and shear test of typical C/SiC connection structure were carried out, and the influence of contact interface SiC matrix on the structural stiffness during the preparation of the connection structure was analyzed. A dynamic modeling method for C/SiC connection structures was established by using spring elements to simulate C/SiC screws and cohesive elements to simulate the deposited substrate at the contact interface. Modal tests were conducted on C/SiC lap plates under free boundary conditions, obtaining the first five modal frequencies and modes. Based on parameter optimization methods, the stiffness of the spring element and the cohesive element were identified.