Tensile Failure Analysis of Carbon Fiber Composite Material L-shaped Joint

In this article, the tensile failure mechanism and load-bearing capacity of the equal-thickness (ET) and variable-thickness (VT) L-shaped joint structures of CCF300/QY9511 materials in different transition regions were analyzed by numerical simulation and experiments. Based on the ABAQUS finite element simulation software, the improved Hashin criterion and the stiffness reduction method considering damage accumulation were used to write a user-defined subroutine, establishing a progressive damage model for carbon fiber composite materials. Numerical simulations were carried out to investigate structural failure and obtain the damage generation, evolution, and failure process of the L-shaped joint structure with bolt connections. The bearing capacity of the structure under two forms of equal-thickness transition and variable-thickness transition were studied in comparison; and the failure mechanism of the structure was determined by comparing with the experimental results. The study found that there were different failure mechanisms in the two joint structures: when the ET joint was loaded, the damage occurred first around the bolt hole, and then the damage expanded to the arcs until it completely failed; the initial failure of the VT joint occurred at the arcs, but when the load continued to increase to the peak load, the damage occurred near the bolt hole of the L-shaped frame, and the load dropped sharply.