Efficient simulation of Bragg grating sensors for implementation to damage identification in composites

Abstract

A computationally efficient method is proposed to interpret optical fiber sensor data collected from Bragg grating sensors embedded in composites. The method divides the composite into remote field and critical field regions with respect to any developed damage. These regions are defined via non-uniformities in the sensor response. The remote field response is treated via an optimal shear-lag theory first presented by Mendels and Nairn. This formulation provides a rapid solution of the average fiber axial stress at the location of each sensor. The critical field region is modeled via a finite element sensor model including the effects of multi-axis loading on the sensor and an optical loss due to local fiber curvature. The response of the Bragg grating sensor to the effects of axial, bending and shear loading are simulated for inclusion in the model. The bending loss response as a function of fiber curvature is experimentally measured. The application of this method is demonstrated through a numerical example, simulating the response of sensors embedded in a lamina to the presence of a transverse crack.