Abstract
Crack orientation, a critical parameter, significantly affects the dynamic properties of composite structures. Experimental free vibration tests were conducted on carbon fiber-reinforced polymer (CFRP) composite plates at room temperature with different crack orientations. Dynamic properties such as damping ratio (zeta), natural frequency (f(n)), and storage modulus (G') were measured using a four-channel dynamic pulse analyzer. Multisensors were mounted on the test plate to pick up the vibration signals. Experimental modal analysis was performed to identify the first three mode shapes of the defective plates. A numerical model using ANSYS software was developed via parametric investigation to predict the correlation between crack orientation and resonant frequencies with corresponding mode shapes. The orientation of the introduced cracks had a significant effect on the dynamic properties of CFRP composites. Vertical cracks had the most significant influence on the eigenvalues of the mode shape frequencies. Furthermore, the damping ratio was an effective method to detect the cracks in CFRP composites.