Nondestructive evaluation of residual stress via digital holographic photoelasticity

Abstract

The nondestructive evaluation of residual stress forms a very important aspect of structural engineering. In this context, as per the theory underlying digital holographic photoelasticity, the residual stress field in a transparency can be efficiently and nondestructively evaluated with high accuracy by varying the polarization direction of the reference light beam. In this study, we use a setup to experimentally verify the above mentioned hypothesis. We first record digital holograms before and after heating optically transparent specimens at four different corresponding positions of the reference light polarization. We next solve the four resulting light intensity equations after digital image processing of the four digital holograms to obtain the residual stress. A comparison of our experimental results with those of the drilling method (the conventional approach to determine residual stress) indicates that our digital holographic photoelasticity method can be suitably applied to the nondestructive evaluation of residual stress in transparencies.