Identification approach to estimate buckling load of damaged composite plates

The application of an indirect approach for prediction of buckling loads of laminated composite plates with flaws or damage, based on the identification of the flexibility influence function of the damaged plate through experimentally measured modal vibration characteristics, is presented. The identified flexibility influence function is used in conjunction with an integral equation formulation to predict the buckling load of the damaged plate. Experiments on laminated composite plates with simulated delamination, impact damage, local step changes in thickness, and cutout have been carried out. The predicted buckling loads and modes are compared with buckling loads obtained from the actual buckling tests of these plates. The close matching between the predictions and test results shows that the lateral stiffness degradations caused by the presence of flaws and damage can be effectively captured using the identification technique.