Whilst quality standards and damage tolerance techniques are unique for each industry, within the aircraft industry there is an overarching need to maintain flight safety. As the aircraft industry continues to strive for improved fuel efficiency and reduced airframe weight there is growing use of advanced laminated carbon fibre reinforced polymers (CFRP) in all types of structures. Therefore, it is essential to predict the future mechanical behaviour and service life of "flight critical structures" made from CFRP in such applications. Experimentally validated failure simulation models are not abundant in the literature for modern CFRP laminates and complex structures. Neither is there abundant quantitative data capable of defining the characteristics of initial microscopic damage evolution in such orthotropic laminates. Early prediction and modelling of damage nucleation and subsequent evolution is thus precluded due to insufficient experimental data. In this work, it is proposed to analyze the 3D microscopic damage behaviour observed in CFRPs subjected to service-replicated (e.g. spectrum) fatigue loading. Probing the evolution of the cracks and damage was performed using X-ray micro-computed tomography (XR-microCT) which proved to be a reliable non-destructive testing (NDT) tool for qualitatively visualizing and monitoring damage mechanisms relative to the fatigue life. Findings may be potentially employed to develop and validate enrichment functions developed to span the asymptotic fields at the crack-tip for implementation in X-FEM to simulate combined damage mechanisms. The work described in this paper is the first step in a larger project to quantitatively examine fatigue damage progression in advanced aerospace composites. Copyright 2014 by Naglaa ElAgamy.

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Conference SAMPE Tech Seattle 2014 Conference
ElAgamy, N. (Naglaa), Laliberte, J, Gaidies, F, & Goldak, J. (John). (2014). Qualitative characterization of fatigue damage propagation in laminated carbon fibre reinforced polymers by using micro-computed tomography. Presented at the SAMPE Tech Seattle 2014 Conference.