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Measurement of Residual Stress Based on a Ring FBG Array

Based on the hole-drilling strain sensing method, a ring fiber Bragg grating (FBG) array is proposed to realize comprehensive and convenient measurement of residual stress for homogeneous or inhomogeneous materials. All FBG sensors are arranged tangentially along the edge of the ring. With the ring array around the drilled hole, more detailed information of the residual stress can be obtained such as the location and the degree of inhomogeneity. The tangential arrangement of FBG sensors can achieve comparable measurement results with the radial arrangement but it brings convenience for the drilling process without any overlap upon the hole position. This method promotes the application of the FBG sensors in the residual stress measurement field.