Negative-Stiffness and Snap-Through Photopolymer Architectures: Stability, Hysteresis, Fatigue and Control

This review asks when the snap-through response becomes large enough to change engineering decisions rather than merely laboratory observables. The physical core is the coupled balance that governs snap-through architectures, but the realised response also depends on the fact that resin viscoelasticity contributes hysteresis on top of geometric hysteresis. In parallel, printing asymmetry biases nominally symmetric switching states. The proposed workflow therefore combines complete switching loops, state-geometry metrology, cycle statistics and instability-mode imaging, mechanism-separating tests such as 'quasi-static and rate-dependent switching tests', and validation outside the calibration condition. Qualification is expressed as a bounded claim about switching-force window with adequate margin, with requalification required when geometry, history or environment changes regime.

ER-364.