Non-destructive evaluation of smart materials by using extrinsic Fabry-Perot interferometric and fiber Bragg grating sensors

The real-time non-destructive evaluation (NDE) technologies of engineering structures are very important to assess the performance of in-service structures. It is very difficult to carry out the on-line structural integrity monitoring by using classical NDE methods. Fiber optic sensors in smart structures provide a unique opportunity to real-time monitor the structural health status by using embedded sensors. This paper examines the possibility of extrinsic Fabry-Perot interferometric (EFPI) and fiber Bragg grating (FBG) sensors for NDE of composite and aluminum structures. The experiments of 3-point bending measurement of composite laminates and aluminum plates with and without damages by using the EFPI and FBG sensors are performed, respectively. The experimental results show that the flexural strain of damaged structures is much higher when compared with relevant undamaged structures under same bending load by using both EFPI and FBG sensors. Furthermore, an excellent accordance was found between the results of the 3-point bending tests by using surface-mounted EFPI and FBG sensors (C) 2002 Elsevier Science Ltd. All rights reserved.