<p align="center">&nbsp;</p><p>In this paper, the effective behavior of shape memory alloy (SMA) triply periodic minimal surface (TPMS) structures is investigated by means of finite element analysis and numerical homogenization method. For this purpose, the onset and subsequent thresholds of phase transformation behavior are determined considering TPMS primitive, gyroid and diamond unit cells,&nbsp;subjected to different loading conditions. When these structures are subjected to uniaxial loading, It is found that the distribution of both effective stress and martensite volume fractions vary from one type of structure to another, but following a quite similar trend. In the case of multi-axial loading, it is observed that&nbsp;at lower void ratios, the initial phase transformation loading surfaces corresponding to the different geometries considered are found to be reasonably well represented by an&nbsp;anisotropic Hill’s criterion. The observed fit, which also depends on the geometry considered, degenerates as the void ratio increases. The determination of the subsequent loading surfaces as a function of the effective volume fraction of martensite shows a nonlinear hardening behavior, which seems to follow a similar trend for the different geometries considered. Ultimately, the loading surfaces are found to reach an asymptotic state with distinctly different features as&nbsp;compared to their initial shapes.</p>

Effective Initial and Subsequent Loading Surfaces for Phase Transformation in Triply Periodic Minimal Surface Shape Memory Alloys

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2021/volume/85499

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