On damage development in mechanically fastened composite laminates

A comprehensive experimental program was conducted to measure and characterize 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 were loaded in quasi-static cycles with successively increasing loads, and damage development in the vicinity of the bolt holes was detected using different methods such as strain measurements, acoustic emission, X-ray and microscopic examination. Several failure modes were detected in a series of events starting at load levels far below the level at which the first visible evidence of damage appeared on the load-displacement curve. Failure modes included matrix cracking, fibre fracture, delamination and kinking. (C) 2000 Elsevier Science Ltd. All rights reserved.