Instantaneous phase-stepping photoelasticity and hybrid stress analysis for a curving crack under thermal load

Stress fields around an oscillating crack tip in a thin plate are analyzed using a hybrid method of photoelasticity and finite element analysis. Instantaneous phase-stepping photoelasticity using a CCD camera equipped with a pixelated micro-retarder array is used for measuring the stress fields around a propagating crack tip in a quenched thin glass plate. The distributions of the principal direction as well as the principal stress difference around a growing crack are obtained. Then, the values of the principal direction and the principal stress difference are used for determining the boundary condition for a local finite element model. Using the boundary condition that is determined from the measurement results inversely, the stress distributions around a crack are evaluated. It is shown that the stresses around the crack tip can be evaluated using the proposed hybrid method. Results show that the proposed hybrid method is effective for the study of crack growth behavior in the quenched glass plate.