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 sid es of the specimen to prevent global buckling. Using the fixture, grap hite/epoxy plates are crushed edgewise against an adjustable inclined plane surface and the energy absorbency is measured. Consistent test d ata are obtained that are similar to those obtained using different sp ecimen geometries, indicating the acceptability of the test method. Re sults suggest that the off-axis crushing response may be described by considering the occurrence of a failure mode separately from the quant itative performance of the mode. Under off-axis loads, the energy abso rbency of a specimen is dependent upon the failure mode experienced, b ur not directly on the orientation of the applied load. However, load orientation affected the preferred failure mode.