Fiber Bragg-Grating Sensors for SHM and FEM of In-Service Bonded Multi-Material Pi-joints

摘要

Prediction of the performance and the failure initiation in in-service adhesivelyrnbonded multi-material Pi-joints is of special interest for determining the maximumrnload carrying capacity and structural integrity of resulting components for marine,rnautomotive and aerospace applications. Currently fiber Bragg-grating (FBG) sensorsrnare being increasingly used to monitor the bonded region in adhesive joints as they dornnot affect the intrinsic bonding properties. This paper presents experimental andrnnumerical study on in-service multi-material Pi-joints using strategically embeddedrnFBG sensors. In-house manufactured Pi-joints consisted of various combinations ofrnAluminum, Steel and Glass Fiber Reinforced Polymer (GFRP) as adherends and usedrnFM-94K adhesive provided by Cytec as the structural adhesive. Apart from intact Pijoints,rnPi-joints with the manufacturing defect were also manufactured. Initially, FiniternElement Modeling (FEM) was used to predict the behavior of Pi-joints with similarrnand dissimilar adherends under varying load conditions. Afterwards, FBG sensorsrnwere strategically placed in the regions of interest to monitor the strains during thernlongitudinal and transversal static loading of Pi-joints. A novel method for externalrnFBG embedding was proposed and validated using strain gages. Proposed methodrnallows easy remove and reuse of the FBG sensor. Strains measurements acquired byrnFBG sensors were validated by strains measurements obtained using strain gages.rnExperimental data from the embedded FBGs is further used to develop experimentallyrnvalidated simulations (EVS) which in turn can be used as a design tool for multimaterialrnPi-joints. Preliminary results demonstrate potential of the developedrntechnique to predict the strain behavior and evaluate the performance of bonded Pijointsrnwith similar and dissimilar adherends.