Pointwise fiber Bragg grating displacement sensor system for dynamic measurements.

A method for setting up a fiber Bragg grating (FBG) sensor which can measure the pointwise, out-of-plane or in-plane dynamic displacement is proposed. The proposed FBG sensor is reusable. A multiplexing demodulation system based on a single long-period fiber grating is used in this study. The experimental results of the steady-state motion for a multilayer piezoelectric actuator and the dynamic response of a cantilever beam subjected to impact loadings are presented. These results indicate that the proposed displacement sensor has the ability to measure the out-of-plane dynamic displacement with high sensitivity. Measurements for a piezoceramic plate excited by high frequency show that the proposed displacement sensor also has the ability to provide the in-plane dynamic displacement up to 20 kHz.