Elastic–Plastic Modeling and Experimental Characterization of Granular Jamming Actuators

Granular jamming enables soft actuators to transition rapidly between compliant and rigid states, yet the disordered microstructure of jammed particles has long precluded rapid predictive modeling. Here, we develop and validate a pressure‐dependent moment–curvature constitutive framework based on elastic‐perfectly‐plastic mechanics, describing the evolution of internal stress distributions during loading and unloading for granular jammed beams spanning vacuum pressures from 0 to 101 kPa and a broad geometric design space. The model is validated against three‐point bending experiments, which are used to identify the effective granular modulus and yield stress . Across the loading branch, the framework shows strong agreement over the tested design space, with deviations remaining within about 10% NRMSE. It also captures the transition from a membrane‐dominated response in the unjammed state to a granular core‐dominated response in the jammed state, together with the onset of plasticity, residual deformation, and hysteresis. Experiments further show an order‐of‐magnitude increase in force response upon jamming, while a systematic parametric study identifies beam diameter as a dominant design parameter affecting peak force and energy dissipation. The resulting framework provides a predictive reduced‐order design tool linking material and geometric choices to the mechanical response of tunable‐stiffness structures.