OFF-AXIS ENERGY-ABSORPTION CHARACTERIZATION OF COMPOSITES FOR CRASHWORTHY ROTORCRAFT DESIGN

The characterization of the off-axis crushing of composite materials i s investigated experimentally and analytically. A fixture for crushing plate specimens against an adjustable inclined plane is reviewed. A p henomenological finite element model is developed based upon results f rom tests of flat plate specimens crushed in the fixture. The model is based upon quasistatic crack growth along ply interfaces, and results in a one-parameter representation to predict the failure mode for a g iven crushing angle; however, no quantitative performance estimation i s provided by the model. The model and the experimental results combin e to produce a hybrid model whereby the crushing performance may be pr edicted for a given loading condition.