Growth of delaminations in thick GRP laminates subjected to quasi-static loading

Models for predicting growth of delaminations in laminated composites are known to be useful for (1) design of damage tolerant components; (2) development of accept/reject criteria for manufactured parts; (3) repair/replace decision making for components damaged in service. As a result, numerous studies have been and are being conducted to develop and validate tools for carrying out delamination growth calculations. In the present study, experiments were conducted on 30mm thick glass fiber reinforced polymer (GRP) matrix composite beams and plates to assess the validity of both traditional and more recently developed delamination analysis techniques. Inputs needed by the delamination growth models were obtained from basic Mode I and Mode II coupon tests. Growth of implanted defects, viz. 0.013 mm thick Teflon(TM) inserts, was measured in composite components subjected to 3- and 4-point bending loads, Several mode-mix ratios were obtained at the delaminations in the bending specimens by varying the location of the defect through the thickness, support lengths and loading configuration. Numerical simulations of the bending tests were conducted using analytical and finite element methods and results were compared to the experimental data.