Experimental Investigation and Numerical Simulation of Bonded, Bolted, and Hybrid Joints in CFRP Laminates Under Tensile Loading

In this study, an in-depth analysis is carried out to simulate the failure mechanism of T700 carbon fiber-reinforced polymer composite (CFRP) joints with a layup sequence of [45/-45/0/90]_3 s when subjected to tensile loading, both experimentally and numerically. We compared the mechanical performance of three different edge-to-bolt diameter ratios (E/d) of bonded, bolted, and hybrid single lap joints subjected to tensile loading. A finite element-based progressive damage method (PDM) along with the bilinear triangular cohesive zone model (BTCZM) is developed to predict the damage evolution and failure mechanism for all joint configurations. By juxtaposing the simulation outcomes and the experimental data, we observed the failure morphology and assessed the bearing capacity of the joint under tensile loading. The comparison results revealed a minor discrepancy of merely 5.5% in terms of joint load capacity between simulations and experiments, which indicates the high accuracy of our model. The strength of the adhesive and mechanical joints increases with E/d from 3 to 5; however, the strength of the hybrid joints decreases. At E/d = 3, hybrid joints performed significantly better than bonded ones, with a remarkable enhancement of 41.53%. However, for E/d ratios of 4 and 5, both simulation results and test data showed that hybrid joints were inferior to bolted joints. The analytical methodology presented in this paper offers a valuable reference for future analysis and design of composite joints.