Postbuckling failure of composite plates with central holes

The postbuckling failure of square composite plates with central holes is analyzed numerically and experimentally. The particular plates studied have stacking sequences of [± 45/0/90]₂₅, [± 45/02]₂₅, [± 45/06]₅. and [± 45]₄₅. A simple plate geometry, one with a hole diameter to plate width ratio of 0.3 , is considered. Failure load, failure mode, and failure locations are predicted numerically by using the finite-element method. The predictions are compared with experimental results. In the experiments in order to be accommodated by the test fixture it is necessary for the plates to be slightly larger than the analYSis region, extending somewhat beyond the supports. The region outside the supports is included in the numerical study. It is shown that not considering these regions can lead to erroneous numerical predictions. In numerical failure analysis the interlaminar shear stresses, as well as the inplane stresses, are taken into account. By comparing the interlaminar shear stress calculations from the finite-element method with analytical results for simple cases, a solid foundation for interlaminar shear stress calculation is established.