Detecting an Arrested Crack in a Foam-Core Sandwich Structure Using an Optical Fiber Sensor Embedded in a Crack Arrester

Abstract A crack arrester was recently developed to suppress crack propagation along the interface between the facesheet and the core in a foam-core sandwich structure. The crack arrester is a semi-cylindrical stiff material inserted into the interface. The crack arrester decreases the energy release rate at the crack tip by suppressing local deformation around the crack. If the arrested crack can be instantaneously detected, the damage tolerance of foam-core sandwich structures can be dramatically improved. This study establishes an innovative crack detection technique using two fiber Bragg grating (FBG) sensors embedded at both edges of the arrester. The change in strain distribution in the crack arrester induced by arresting the crack is evaluated using reflection spectra from the FBG sensors. The proposed technique enables an effective application of the crack arrester and significantly improves the reliability of foam-core sandwich structures. Keywords: FOAM-CORE SANDWICHINTERFACE CRACKCRACK ARRESTERSTRUCTURAL HEALTH MONITORINGOPTICAL FIBER SENSORS