Impact damage detection and evaluation in graphite epoxy motorcases (GEM)


To appear in the proceedings of Emerging Technologies in NDT, Held 26-28 May 2003, Thessaloniki, Greece

R.D.Finlayson, M.A.Luzio, V.Godinez-Azcuaga, A. Anastassopoulos, P. Cole


There is a sizable need for composite health assessment measures for the detection of damagefrom impacts and other sources of high mechanical and thermal stresses. Even low-momentum impacts can leadto “barely visible impact damage” (BVID), corresponding to a significant weakening of the composite. Thisdamage can in turn lead to sudden and catastrophic failure when the material is subjected to a normal operatingload. The results presented in this paper contribute significantly to the understanding of the acoustic wave prop-agation properties of a graphite epoxy motorcase (GEM), and present a substantial advancement in the devel-opment of a damage source location algorithm. By performing an in-depth analysis of the behavior of travellingacoustic waves in the graphite epoxy structure, it was possible to understand how graphite epoxy propertiesinfluence acoustic wave propagation. An analysis of waveforms, attenuation and velocity measurements of dif-ferent propagation modes, and analysis of Acoustic Emission (AE) features was performed.