Impact damage and residual tensile strength of a CF-SMC composite

In this study, the impact damage and the tension after impact (TAI) strength of a carbon-fiber-reinforced sheet molding compound (CF-SMC) are analyzed. First, low-velocity impact damage is introduced to several CF-SMC coupon specimens for a variety of impact energies. Next, the impact damage is observed by ultrasonic inspection and optical microscopy to determine the damage state and quantify the damage area and depth. Then, the TAI strength is measured and correlated with such parameters as maximum impact load, impact energy, and damage area and depth. Finally, a simple fracture-mechanics model for predicting the TAI strength is proposed. It is proved that the TAI strength depends on the impact damage depth.