Photoelastic determination of three-dimensional stresses occurring around microinclusions in polymers

Two photoelastic methods are described, viz., the transmission method (Figs. 1, 2) that avails itself of symmetry of the system to reconstruct the stressed state from light polarization variations, and the scattered light method (Figs. 6, 7) in which symmetry is not required. However, the small variations of scattered light intensity in the stressed area require sensitive instruments and specially prepared samples to be used in measurements. Each method was applied to determine the distribution of stresses in variously stressed epoxy resin blocks containing inclusions and subjected to various forces (Figs. 3-5, 8).