Loading Rate Dependence of Elastic Hysteresis in 3D-Printed Resin Metamaterials

The aim of this study is to experimentally compare the influence of loading rate and prior stress history on the deformation response of 3D-printed photopolymer metamaterials. Experimental measurements were performed on three identical specimens under three different loading phases. The results showed that the hysteresis loops stabilize as early as the first cycle, with the most significant decrease in dissipated energy between the first and second cycles reaching 14.19% at a loading rate of 100 mm/min. A comparison of the individual phases confirmed that the previous loading history has only a marginal effect on the overall nature of the response. The maximum dissipated energy reached 75.85 mJ for an unused sample, while for repeatedly loaded samples it decreased slightly to 68.46 mJ. These findings confirm the high repeatability of the mechanical behavior and the structural stability of the metamaterials under study.