Mode I delamination mechanism analysis on CFRP interference-fit during the installation process

The wide application of composite materials in aerospace raises a new challenge for the joining technology. Though interference-fit can enhance joint strength, potential delamination damage also emerges for oversized percentage. A delamination analytical model during the interference-fit pin installation process is established in this paper. It consists of the critical delamination force (CDF) induced by mode I delamination and the pin-hole friction. The establishment of CDF model is based on fracture mechanics, classical bending plate theory and the mechanics of composites, and the friction model is built with classical anisotropic plate theory and friction law. Cohesive element (CE) based delamination simulation with bilinear softening constitutive law is made, and corresponding pin installation experiments are also conducted. The effect of interference-fit percentages and residual layers on CDF was analyzed and the critical interference percentage below which delamination-free hole can be obtained was also proposed. Finite-element delamination results and experimental delamination specimens were analyzed and the rationality of the model was testified.