SHM of Composite Patch Repairs Using Chirped Fiber Bragg Grating Sensors

Abstract

The application of health monitoring systems to reduce the penalizing safety factors in composite repairs such as joints and adhesive patches is of considerable importance in critical components where non-destructive tests are difficult to perform. In this paper, a structural health management strategy to monitor patch repairs in carbon/epoxy structures is presented. The feasibility of using Chirped Fiber Bragg Grating sensors was analyzed with gradual heat tests, while evaluating their capability of sensing the presence of strain field variations along their physical length. The presence of patch debond was obtained by the reflection spectrum from the sensor, and also its size was estimated with reasonable accuracy. The same set of sensors were placed and embedded into patches, and two methods were used based on the calibration charts and tables obtained experimentally. For evaluation and verification, a finite element analysis of the problem was carried out, supported by tensile tests for material characterization. Good results were obtained from the experiments.