Acoustic emission sensor properties of active fibre composite elements compared with commercial acoustic emission sensors

摘要

Active fibre composite elements (AFCs) based on piezoelectric fibres are used as acoustic emission (AE) sensors on composites (unidirectional glass-fibre and carbon-fibre reinforced epoxy) and polymer (polymethyl-methacrylate, PMMA) plates. AFCs are mounted reversibly or permanently bounded to the plates. Their performances are compared with that of commercial AE sensors. The sensitivity of both sensors is characterised using signal attenuation curves and polar diagrams. The data indicate a large anisotropy behaviour of the AFCs in comparison with conventional AE sensors, leading to higher sensitivity of AFCs along the direction of the piezoelectric fibres. The emission of simulated AE by AFCs and AE sensors is also studied. Transient electric impulses applied to the AFC yield short vibrations transmitted to the testing object, that can be sensed by other AFCs or AE sensors. Permanently bonded AFCs show promising sensing and emitting properties for possible acousto-ultrasonic applications in composite laminates. (C) 2004 Elsevier B.V. All rights reserved.