Quasi-static damage evolution of carbon fiber-reinforced polymer laminates under three-point bending

Carbon fiber reinforced polymer (CFRP) laminates inevitably undergo bending loads during service, but bending failure modes are complex and not fully understood. This study investigates the quasi-static progressive damage of CFRP laminates under three-point bending primarily through finite element analysis, with experiments serving to validate the overall trends and final failure modes. The influence of interlaminar shear strength (ILSS) and stacking thickness on the flexural properties is studied. Experimentally, as the stacking thickness increases from 0.6 mm to 1.2 mm, the flexural strength decreases from 2099 MPa to 1790 MPa. When ILSS increases from 20 MPa to 80 MPa, the peak load increases by approximately 1.4–1.9%, and the simulation indicates that the predominant failure mode tends to shift to fiber fracture. To analyze the damage evolution behavior of the interlaminar interface, an interlaminar interface catastrophic failure model based on Taylor expansion is established. The damage of the interlaminar interface exhibits a power-law characteristic in the simulation with a power exponent of 0.5. At ILSS20 MPa, the damage coefficient λ increases from 1.88 to 4.70 as the stacking thickness increases. As the displacement approaches the failure point, the damage rate rises rapidly, suggesting a power-law singularity (−0.5).