Wet deck slamming experiments with a FRP sandwich panel using a network of16 fibre optic Bragg grating strain sensors

Drop test experiments have been performed with a FRP sandwich panel instrum ented with a network of 16 fibre optic (FO) Bragg strain sensors, together with conventional electrical strain gauges for control and verification. Th e drop tests simulate slamming loads on the wet deck of a surface effect sh ip (SES), The objectives were to show the possibility of using a network of FO sensors to monitor strain during a slamming; impact, and to test out a technique for signal processing. The strain measurements provided both peak strain data and served as a base For frequency analysis. The results showe d that the FO strain sensors performed satisfactorily and were in general a greement with the conventional strain gauges used. The FO interrogation sys tem was, however, not designed with sufficiently large dynamic range for th e most extreme drop sequences. The peak strain in the panel was found to in crease almost proportionally with the drop velocity, or drop height, and th e wet fundamental frequency increased with increasing drop angle. Furthermo re, the frequency decreased with increasing drop velocity. (C) 2000 Elsevie r Science Ltd. All rights reserved.