New Method of Full-Field Stress Analysis and Measurement Using Photoelasticity

Photoelastic measurements provide a means to obtain a meaningful representation of the stress state in a granular material over the full area of a plane-strain sample without the need to place stress transducers inside the sample. This method uses the property of non-crystalline materials to become optically anisotropic when put under stress. To measure the resultant relative retardation of a light beam transmitted through a model built from glass grains and a liquid with a matching refractive index in the pores, a full-field polariscope has been built. This setup is able to characterize the stress state in the full-field of the sample with only seven intensity measurements. A plane-strain pile penetration test is used as an example.