Three Dimensional Displacement Measurement of Transient Elastic Wave Propagation Using a Multidimensional Point-Wise Fiber Bragg Grating Displacement Sensor System

Abstract

A fiber Bragg grating (FBG) sensor setup method that can allow the FBG to detect out-of-plane or in-plane point-wise displacement is demonstrated in this study. Based on this method, we successfully establish a multidimensional sensing system which contains one out-of-plane displacement sensor and two inplane displacement sensors to measure the transient elastic wave propagation in a square thick plate subjected to impact loadings. The proposed system employs wavelength-optical intensity modulation techniques based on a long-period fiber grating filter and two FBG filters. The transient responses of out-of-plane particle motions measured by the FBG displacement sensor are compared with those obtained simultaneously by a laser Doppler vibrometer (LDV). The experimental results show that the proposed FBG displacement sensor system is capable of performing real-time measurement of three dimensional dynamic displacements for transient elastic wave propagation.