LIFE CYCLE STRAIN MAPPING BY OPTICAL FIBER SENSORS FOR DEFECT AND DAMAGE DETECTION OF CFRP STRUCTURES

摘要

We propose structural health monitoring (SHM) technology based on the strain mapping ofrncomposite airframe structures through their life cycles including the stages of molding,rnmachining, assembling, operation, and maintenance. Our SHM system detects damage andrndeformation harmful to the structures by strain mapping using fiber Bragg grating (FBG)rnsensors. In this paper, we firstly carried out a strain monitoring test of CFRP mock-up structurernthrough the life cycle including the stage of molding, machining, assembling, and operation. Thernexperimental result confirms that the strain which occurs in each life cycle stage can bernmeasured by FBG sensors embedded in molding stage and demonstrates the feasibility of liferncycle structural health monitoring by using FBG sensors. Secondly, we conducted the strainrnmonitoring test of CFRP scarf-repaired specimen subject to fatigue load. FBG sensors werernembedded in the specimen and their reflection spectra were measured. Specimens were inspectedrnby pulse thermography. As a result, strain measured by FBG sensors changed sensitively withrndebonded area of repair patch, which demonstrates that the debondings of repair patches in scarfrepairedrncomposites due to fatigue load can be detected by FBG sensors.