Orthogonal Photoelastic Imaging for Three-Dimensional Stress Estimation in a Transparent Cubical Block

Conventional photoelastic methods are largely limited to two-dimensional stress visualization, leaving a gap in techniques that can capture three-dimensional force interactions with high sensitivity at low stress levels, a capability that is critical for biomechanics and dynamic force analysis. This study develops and demonstrates a cubic photoelastic model that enables accurate fringe-order estimation from three orthogonal views, providing a foundation for reconstructing full three-dimensional stress states. A transparent, low-elasticity epoxy cube, free of prestress, was fabricated and examined using combined transmission and reflection photoelastic imaging. Three mutually orthogonal isochromatic fringe fields were recorded simultaneously under a single applied load. Image analysis employed a peak-valley intensity method to extract sub-fringe orders and to resolve low-stress cases with minimal noise. The cubic block produced high-quality fringe patterns in all directions, enabling separation of tangential and normal stress components. Independent orthogonal views confirmed directional sensitivity and yielded consistent fringe-order estimates under low loading, with response times on the order of tens of microseconds. These results establish a practical approach for three-dimensional photoelastic stress measurement from orthogonal views and create a pathway toward full vector force reconstruction with strong potential for biomedical applications and studies of dynamic loading.