Evaluating Effects of Wrinkle Defects on Impact Response and Residual Compressive Strength After Impact in CFRP.

Carbon fiber-reinforced polymer (CFRP) has become widely applied in engineering fields such as aerospace and the automotive industries. Evaluating the damage tolerance of CFRP with manufacturing defects under impact loads is crucial in ensuring the reliable service of CFRP components. In this study, four types of wrinkle defects are designed, and the effect mechanism is thoroughly discussed, focusing on the impact and compressive response. The results indicate that the wrinkle defects primarily affect the impact response via the wrinkle fibers being subjected to impact stress and wrinkle stress concentration. Notably, the first peak contact force of the specimen with a wrinkle at the 12th layer is reduced by approximately 20.00% compared to that of the specimen with a wrinkle at the third layer. Additionally, the first peak contact force of the specimen subjected to a reverse impact direction decreases by about 14.00% compared to that under a forward impact direction. The impact direction also plays a significant role in the impact response by altering the loading conditions of the wrinkle fibers during impact. Regarding the compressive performance after impact, specimens with a wrinkling layer close to the impact surface show a slight 4.80% increase in residual compressive strength, which is attributed to the greater suppression of impact damage by the wrinkle fibers. However, all other specimens with wrinkle defects demonstrate varying degrees of reduction in residual compressive strength after impact compared to the specimens without wrinkle defects. The maximum reduction is approximately 27.50% for specimens subjected to a reverse impact direction. Furthermore, the amplitude of the decrease in the residual compressive strength is mainly determined by the matrix damage and delamination that occur during impact.