Static and dynamic testing of a quasi-isotropic composite with embedded optical fibres

An efficient use of composite materials in loaded structures requires NDT t echniques that can reliably monitor the damage state of these materials in situ and continuously during service. A promising solution to this problem is the incorporation of optical fibres into the composite structure during manufacture. However, because optical fibres are always an order of magnitu de bigger than material fibres, stress concentrations will inevitably be cr eated which can lead to premature damage initiation and thus to a reduction in the mechanical properties. Therefore the first step in the development of a damage detection system based on optical fibre technology always has t o be an investigation of the mechanical properties of the resulting structu res. In this paper, optical fibres were incorporated in the different inter faces of a quasi-isotropic composite laminate. Both static and dynamic mech anical tests were carried out to determine the influence of the optical fib res on the mechanical properties of the resulting composite structures. Dif ferences in behaviour between the different configurations were correlated with differences in damage propagation. (C) 1999 Elsevier Science Ltd. All rights reserved.