An experimental characterization of the acoustic fatigue endurance of GLARE and comparison with that of CFRP

GLARE is a new aerospace structural material composed of alternating, bonded layers of aluminium alloy and glass fibre reinforced plastic. The results of an experimental study are presented here concerning mechanical fatigue testing of GLARE structural specimens in conditions relevant to the acoustic fatigue problem. Endurance testing of 35 GLARE Tee-coupons under simulated random acoustic loading has been carried out and resonance frequency, damping loss factor, and strain response of the specimens have been experimentally determined. CFRP specimens have also been tested to provide a benchmark against which to compare the properties of GLARE. FE analysis of the coupons has also been carried out to support the experimental work and the theoretical results have been compared with the experimental data. Damage mechanisms have been observed and fatigue data established. Using these experimental data, surface strain versus number of cycles to failure curves have been established. In particular, this work has assessed the behaviour of GLARE in bending and has highlighted the importance of the lay-up sequence for the “fibre bridging effect” on crack propagation to be effective.