The Simulated Distortion Spectrum on Aluminum Alloy Structure with the Fatigue Crack Propagation

Abstract

Fiber Bragg Grating (FBG) is expected to be a means of real-time monitoring of crack damage at the edge of the hole due to the sensitive perception of strain. In this paper, an optical fiber fatigue monitoring test platform is built for real-time monitoring of hole edge crack damage. Experimental results found that the grating could be sensed the strain variation with the crack propagation, caused by crack singularity, and the spectrum is highly correlated with the crack length. Full width at half maximum (FWHM) is a type of damage feature extracted from the simulated distortion spectrum, which has a high correlation with crack propagation. Meanwhile, the signal processing technique is used for the FWHM extraction, and the spectrum simulation, combined transfer matrix method and the finite element method, is investigated in this paper. The results show that the FWHM broadened obviously with the crack length, and the FWHM can be used as an effective index for evaluating fatigue crack growth.