Monitoring Technology for Stress Corrosion Crack Propagation of Al-alloy Based on Optical Fiber Bragg Grating
In order to understand and monitor the process of stress corrosion crack propagation of engineering equipment in service,the study focuses on the propagation of stress corrosion cracks of a designed double cantilever specimen of high-strength Al-alloy with prefabricated crack.Firstly,the mecha-nism of stress corrosion crack propagation was described,and the linear relationship of the crack length with the variation of the strain in the x-and y-directions of the stress corrosion crack propagation tip was determined through Matlab simulation;The stress concentration area at the crack tip was further deter-mined by Abaqus finite element simulation,afterwards,the distance between the position of optical fiber sensing probe and the crack tip was selected to be 10 and 15 mm respectively;The relevant sensing technology of stress corrosion crack propagation in fiber Bragg gratings was also studied,and then a grating temperature compensation model was proposed;Finally,the correlation between the crack length and the wavelength change of the fiber Bragg grating sensor during corrosion crack propagation was calibrated.The results showed that the correlation of the crack length and the wavelength change was R2=0.9893 and R2=0.9870,respectively;Afterwards,an outdoor exposure test set was constructed in Wanning of Hainan Province,to achieve in-situ monitoring of stress corrosion crack propagation of Al-alloys through networking.The monitoring data showed that after adopting the suitable temperature com-pensation,the measurement error is only 2.61％for sensor positioned 10 mm near the crack tip,and the monitoring results can provide data support for the real operation of engineering equipment.
万方数据
维普
