The Energy Absorption of Composite Plates under Off-Axis Loads

A fixture for measuring the energy absorption of composite structures under off-axis loads is developed. The testing fixture stabilizes the specimens by providing simply-supported boundary conditions on the sides of the specimen to prevent global buckling. Using the fixture, graphite/epoxy plates are crushed edgewise against an adjustable inclined plane surface and the energy absorbency is measured. Consistent test data are obtained that are similar to those obtained using different specimen geometries, indicating the acceptability of the test method. Results suggest that the off-axis crushing response may be described by considering the occurrence of a failure mode separately from the quantitative performance of the mode. Under off-axis loads, the energy absorbency of a specimen is dependent upon the failure mode experienced, but not directly on the orientation of the applied load. However, load orientation affected the preferred failure mode.