Influence of Resin Content on the Low‐Velocity Impact Response and Compression‐After‐Impact Performance of Carbon Fiber/Epoxy Laminates

Compression‐after‐impact (CAI) testing is a crucial method for evaluating the damage tolerance of carbon fiber–reinforced polymer (CFRP) structures. However, current research has predominantly focused on interlaminar modification, multiscale structural design, and resin matrix modification, whereas the influence of intrinsic structural parameters of CFRP laminates on CAI performance has not been sufficiently clarified. To address the above issue, this study investigates the influence of resin content on the low‐velocity impact response and CAI performance of CFRP laminates. Three types of carbon fiber/epoxy (CF/EP) prepregs with different resin contents were prepared using a hot‐melt prepregging process. After hot‐press molding, low‐velocity impact tests at multiple impact energy levels and subsequent compression tests were carried out. Ultra‐depth‐of‐field optical microscopy and ultrasonic water‐immersion C‐scan imaging were used to characterize the surface and internal damage morphologies of the impacted laminates. The results indicated that, at the same impact energy, the laminate with 30% resin content exhibited the most favorable peak load, energy absorption capability, and residual compressive strength after impact. At 30 J, the CAI strength of this laminate reached 175.02 MPa, representing increases of 22.7% and 8.02% compared with the laminates with 25% and 37% resin contents, respectively. Overall, the present results indicate that an intermediate resin content provides a more favorable balance between impact resistance and postimpact residual performance under the present test conditions; and the study provides comparative experimental data for understanding the role of resin content in the damage tolerance of CFRP laminates, filling the gaps in existing databases regarding the correlation between laminate fiber volume fraction and CAI strength.