Measurement of longitudinal strain and estimation of peel stress in adhesive-bonded single-lap joint of CFRP adherend using embedded FBG sensor

摘要

In this research, longitudinal strain and peel stress in adhesive-bonded single-lap joint of carbon fiber reinforced plastics(CFRP) were measured and estimated by embedded fiber Bragg grating (FBG) sensor. Two unidirectional CFRPsubstrates were bonded by epoxy to form a single-lap configuration. The distributed strain measurement system is used.It is based on optical frequency domain reflectometry (OFDR), which can provide measurement at an arbitrary positionalong FBG sensors with the high spatial resolution. The longitudinal strain was measured based on Bragg grating effectand the peel stress was estimated based on birefringence effect. Special manufacturing procedure was developed toensure the embedded location of FBG sensor. A portion of the FBG sensor was embedded into one of CFRP adherendsalong fiber direction and another portion was kept free for temperature compensation. Photomicrograph of cross-sectionof specimen was taken to verify the sensor was embedded into proper location after adherend curing. The residual strainwas monitored during specimen curing and adhesive joint bonding process. Tensile tests were carried out andlongitudinal strain and peel stress of the bondline are measured and estimated by the embedded FBG sensor. Atwo-dimensional geometrically nonlinear finite element analysis was performed by ANSYS to evaluate the measurementprecision.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.