NDTnet 1998 Aug, Vol.3 No.8

Abstract

Impact damage is widely recognised as one of the most detrimental damage forms in composite laminates, which dissipate the incident energy by a combination of matrix damage, fibre fracture and fibre-matrix debonding. While in ballistic impacts the damage is very localised and clearly visible by external inspection, low velocity impacts are usually responsible for internal damage, difficult to detect and likely to reduce the load-carrying capability of the laminate. Static deflection tests are often used to easily predict the dynamic response of thermosetting composite laminates to low velocity impacts; for high-toughness thermoplastic composites, however, due to the rate-dependance of the resin properties and to the lack of relevant data, the results obtained by static loading require to be confirmed under dynamic conditions.

In this study, both indentation-flexure and low-velocity impact tests were carried out on graphite/peek laminates. The indenter and the clamping rings were the same for both indentation tests (conducted on a servohydraulic testing machine) and impact tests (carried out with a drop-weight impact rig at different impactor velocities). The internal damage, assessed by means of a range of techniques (X-radiography, ultrasonics, deply, optical microscopy), was related to the absorbed energy and the contact force as obtained by instrumented testing. Test results are compared and discussed to characterize the onset of individual damage modes and to clarify the role of the loading rate in the failure process.

Abstract Source:
Preview of Abstracts, International Conference on Advanced Materials - 1998, Hurghada, Egypt, 15 - 18 December 1998

Full-Text Source:
International Conference on Advanced Materials - 1998, Hurghada, Egypt, 15 - 18 December 1998

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