An improved shell-fastener model for modelling C/SiC composite bolted joints with rough surface characteristics

An improved shell-fastener model is proposed to study the mechanical behavior of C/SiC composite bolted joints with the rough surface (millimetric magnitude). Based on the axial compressive experiment, the normal contact stiffness is obtained by a modified fractal normal contact model, which is also validated by using a solid FE model and a hybrid FE model (shell-fastener and solid nuts). The equivalent axial stiffness and shear stiffness used in the shell-fastener model for the bolted joints are determined combining with normal contact stiffness. In comparison of the experimental results, the improve shell-fastener model with equivalent stiffness under pre-tightening load can efficiently and accurately describe the in-plane tension of C/SiC composite bolted joints. The proposed model has the potential to study the large C/SiC composite structures with a large number of bolted joints.