Low velocity impact localization system of CFRP using fiber Bragg grating sensors

•FBG sensors and a high speed interrogation system were used to detect the signals.•The arrival time differences of each leading wave were calculated for localization.•The localization problem was formulated to an optimization problem.•Intelligent localization method based on LSSVM was proposed for localization.•The experimental data validated the proposed impact localization model.

Carbon fiber reinforced plastics (CFRP) structures are very susceptible to barely visible impact damage induced by low velocity impact. Thus knowledge of the position of an impact event on a CFRP structures can be useful information for detecting this type of damage. In this paper, low velocity impact localization system using fiber Bragg grating (FBG) sensors and localization algorithm for CFRP structures were investigated. The FBG wavelength shifts, caused by impact, were captured by a high speed FBG interrogation system. Wavelet transform was used to weaken signal noise. After that, the arrival time differences of each leading wave were calculated to produce the input data sets for least squares support vector machines (LS-SVM) model training. Finally, FBG impact localization system was constructed and validated on a CFRP plate with 300 mm * 300 mm * 2 mm experiment area. The experimental results showed that the impact position abscissa and ordinate localization errors were all less than 5 mm, and the maximum and average impact localization errors were 5.8 mm and 3.7 mm, respectively. This paper provided a reliable method for CFRP structures impact localization.