On damage development in mechanically fastened composite laminates

A comprehensive experimental program was conducted to measure and character ize the development of damage in the vicinity of fastener holes in graphite /epoxy composite laminates. This was carried out to generate data which can be used for development of appropriate failure criteria. Test specimens we re loaded in quasi-static cycles with successively increasing loads, and da mage development in the vicinity of the bolt holes was detected using diffe rent methods such as strain measurements, acoustic emission, X-ray and micr oscopic examination. Several failure modes were detected in a series of eve nts starting at load levels far below the level at which the first visible evidence of damage appeared on the load-displacement curve. Failure modes i ncluded matrix cracking, fibre fracture, delamination and kinking. (C) 2000 Elsevier Science Ltd. All rights reserved.