A reasonable finite element model was established to simulate composite laminates with delamination by using the user-defined matrix element to simulate contacting element in delamination region for distortion mode of the upper and lower sublaminates

and the selection of connection stiffness values was studied as well.This article focuses on the vibration performance of composite laminates with delamination depth and delamination size.The comparison of numerical simulation and experimental results indicates that it is feasible to simulate the delamination of composite laminates with the user-defined matrix elements; the maximum error of the modal calculation and the experimental values is 10.67%

and the minimum error is 0.34%; delamination depth and size have significant effects on vibration characteristic of composite laminates

and the natural frequency of laminates declines up to 50% with change of delamination depth; the first to fourth order natural frequencies of laminates decrease up to 12% with change of delamination size.