A novel sensor package for fibre Bragg grating (FBG) acoustic emission (AE) based on a lateral coupling cone structure is proposed in this paper. The package is designed to be sensitive and reusable. Numerical modelling of the sensor package structure is performed through the use of finite element analysis for determining the main parameters of the coupling cone structure. An AE source system was built for the experimental work and a pencil lead break (PLB) signal was employed as the artificial acoustic emission source signal. The PLB signal was detected using the new sensor, the narrowband PLB signal was extracted using the Shannon wavelet transform and the simulated annealing multiple signal classification (SA-MUSIC) algorithm was used to achieve the localisation of the direction of the wave. The experimental data demonstrated that the lateral coupling cone fibre grating AE sensor has a maximum error value of −1.3° in the direction of the wave and a minimum error value of −0.2° in the angular estimation. The minimum error of the distance from the source was 4.8 mm and the maximum error was −10.39 mm. The results show that the FBG AE sensor package with lateral coupling exhibits advantages of high sensitivity, flexibility and adjustable positioning; it has achieved positioning of the acoustic emission signal source with useful accuracy.
Liu et al. (Wed,) studied this question.