The manufacturing, characterization and analysis of thick section composites is of interest to researchers due to their potential usage in marine, civil and offshore structures. Imperfections such as porosity and fiber waviness, that arise during manufacturing of thick carbon/epoxy and glass/epoxy composites are investigated in the present study using ultrasonic and vibration methods. NDE parameters in terms of ultrasonic velocity measurements and vibration damping ratios are determined for composite laminates of various thicknesses manufactured by the autoclave process. The acid digestion method is used to determine quantitatively the fiber volume fraction and porosity level in the cured laminates. The effect of such defects on static compression and compression-compression cyclic behaviour of thick composites are investigated. In-situ monitoring of progressive damage in both static and cyclic loading is conducted using the acoustic emission (AE) technique. NDE parameters including ultrasonic velocity and vibration damping ratios are also determined at various stages of static compression and cyclic loading. The failure modes are identified by optical and scanning electron microscopy (OM & SEM) and these observations are correlated with ultrasonic, AE and vibration NDE parameters.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 2, pages 529 - 534 Publisher:Ashgate Publishing Company
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