Leveraging Residual Stresses in 3D Printing for Tension–Compression Aware Photoelasticity

Visualizing and quantifying internal stresses in solids is fundamental to mechanical analysis and design. Photoelasticity, a classic experimental technique for this task, faces two major challenges that hinder its application: the time-consuming manufacture of photoelastic analogs and the inability to readily distinguish tension from compression. Here, we overcome these two challenges by introducing a new technique, tension–compression aware photoelasticity, that is particularly well-suited for 3D-printed specimens. We begin by systematically investigating the residual stress in 3D-printed photoelastic specimens as a function of print orientation. Rather than avoiding residual stresses, as done in conventional photoelastic testing, we leverage them to distinguish tensile and compressive stresses induced by external loads. We demonstrate, using two examples, that our technique quantifies tensile and compressive stresses in structures with good accuracy. Our new technique significantly improves photoelastic testing by accelerating the manufacturing of the photoelastic analogs using 3D printing and endowing photoelasticity with tension–compression awareness.