Eliminating Fringe Streaks in SDM‐Based Photoelastic Stress Separation

ABSTRACT

The shear stress difference method (SDM) plays a central role in photoelastic stress separation. Direct compatibility with standard experimental setups enables straightforward full‐field recovery of stress components. The practical application of SDM is constrained by pronounced fringe streak artefacts and non‐physical discontinuities in recovered normal‐stress maps. These shortcomings arise from three interrelated challenges: (i) irregular fluctuations of the shear‐stress component perpendicular to numerical integration paths that accumulate during integration, producing path‐to‐path discrepancies; (ii) boundary residual stresses that introduce bias in initial‐value determination; and (iii) cumulative errors when integration paths traverse low‐quality measurement zones. To overcome these limitations, we developed a mechanism‐driven framework: it combined (a) a directional smoothing operator targeting perpendicular shear fluctuations while preserving legitimate stress gradients; (b) an informed initial‐value selection rule and a low‐temperature annealing protocol to mitigate boundary bias; and (c) a partitioned reconstruction workflow that prioritized high‐quality regions and propagated interface results into lower quality zones to limit error growth. This framework was validated against an analytical solution for a radially compressed disk and a numerical simulation of a radially compressed ring. The results demonstrated substantial suppression of streak artefacts, restored continuity and strong quantitative agreement with reference fields. This approach was robust and practically implementable, and it provided a reliable foundation for broader photoelastic stress separation tasks.