Three dimensional photoelasticity with equilibrium constraint

A method for stress field tomography based on three dimensional photoelasticity has been developed. The proper treatment of the nonlinearity and the ill-posedness is the key to the robust tomographic method. In the proposed method, the nonlinearity has been addressed by the load incremental approach which divides the nonlinear solution space into segments with unique solutions. Also, the ill-posedness has been suppressed by introducing constraints from the equilibrium of the stress field. Validating both numerically and experimentally, the proposed method is shown to be robust enough and applicable to experimental stress measurements.