NAVAL AIR WARFARE CENTER AIRCRAFT DIV WARMINSTER PA AIR VEHICLE AND CREW SYSTEMS TECHNOLOGY DEPT
Equations for predicting the theoretical stresses and mechanical properties of fibermetal laminates were derived. These were applied to a model high temperature laminate system based on 8OO9 aluminum and glass fiber reinforced U-25 thermoplastic polyimide. The effects of aluminum surface treatment on bond strength were investigated chemical surface treatments gave superior bond strength compared to mechanical treatments. Adequate bond strength was obtained using simplified and environmentally safe surface preparation techniques. The tensile yield and ultimate strength, elastic modulus, fracture behavior, dynamic mechanical behavior, chemical resistance, and fatigue resistance of the laminate were investigated. Most properties were found to correlate well with the theoretical predictions. The laminate showed excellent strength retention at temperatures above 200 deg C. Fatigue resistance as- processed was found to be comparable to monolithic 8009. Post-stretching the laminate was shown to increase both fatigue life and yield strength substantially.