Determination of multi-physics effective properties, and actuation response of triply periodic minimal surface based novel photostrictive composites: A finite element analysis

This paper presents the novel triply periodic minimal surface (TPMS) based photostrictive composite as an alternative to naturally occurring photostrictive materials. The non-thermal, light-induced mechanical strain i.e., photostriction involves the simultaneous action of photovoltaic effect and converse piezoelectric effect. All the effective elastic, dielectric, piezoelectric, and pyroelectric properties are evaluated using the finite element analysis and compared with traditional micromechanical models for fibrous composites. Degenerated shell element is used to simulate the actuation response of unimorph cantilever and simply supported beams bonded with TPMS based photostrictive composite. The proposed photostrictive composite consists of poly{4,8-bis[5-(2-ethyl-hexyl) thiophen-2-yl] benzo[1,2-b:4,5-b'] dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethyl-hexyl) carbonyl] thieno[3,4-b] thiophene-4,6-diyl} (PTB7-Th) as photovoltaic polymer matrix and Pb(Mg_1/3Nb_2/3)O₃–0.35PbTiO₃ (PMN-35PT) as TPMS—based filler material. The proposed TPMS based photostrictive composite induces 10 times larger actuation than 0–3 photostrictive composite. Also, the maximum deflection (3.22×10⁻⁵ m) of cantilever smart beam, achieved with Schoen-I-WP based photostrictive composite, is more than that achieved with Schoen-gyroid based photostrictive composite i.e., 2.78×10⁻⁵ m. Similar trends are obtained for simply supported smart beam where the center deflection for Schoen-I-WP based photostrictive composite and Schoen-gyroid based photostrictive composite are found to be 4.04×10⁻⁶ m and 3.49×10⁻⁶ m, respectively. The proposed novel photostrictive composite has potential for future wireless actuation applications.