Analytical and Experimental Studies of Crushing Behavior in Composite Laminates

The objective of this research effort has been to gain a better understanding of energy absorption behavior in composite laminates. Crush tests of nine flat plate specimens with three different lay-ups of T650-35/F584 graphite/epoxy fabric were performed to evaluate the mechanisms that contribute to the energy absorption process. A nonlinear finite element approach was used to model the sustained crushing of the flat plate, and a progressive failure model was implemented as part of the finite element analysis to enable modeling of the fundamental mechanisms involved in the crushing behavior. The progressive failure model was based on linear elastic fracture mechanics for prediction of crack growth and a set of failure criteria for predicting fiber/matrix failures that occurred as a result of large deformations. Friction between the specimen and the crushing surface was included in the model. Predicted values of sustained crushing stress agreed with experimental results for the flat plate specimens within nine percent.