Measurements of transient elastic wave using a fiber grating displacement and strain sensing system

We demonstrate an all-fiber three-dimensional dynamical measurement system as well as a gluing concept for setting up fiber Bragg grating (FBG) displacement or strain sensors with high sensitivity. To show the dynamic measurement ability of the proposed system, the multidimensional transient elastic wave propagation in an Aluminum thick square plate subjected to impact loadings is investigated. The proposed system employs an FBG filter as well as a long-period fiber grating (LPFG)-based wavelength-optical intensity modulation technique. To verify the dynamic sensing ability of the proposed sensing system, a non-contact laser Doppler vibrometer (LDV) as well as traditional strain gauges are employed to compare the transient results measured by the FBG sensors. Frequency contents of the transient in-plane displacement and strain responses are compared to further demonstrate the dynamic sensing ability of the FBG sensors.