The Coupled Effects of Microstructure and Topology on the Piezoelectricity of Additively Manufactured Bi‐Continuous Piezocomposites

ABSTRACT Bi‐continuous piezocomposites with triply periodic minimum surfaces (TPC) are emerging flexible piezoelectric materials. The ceramic skeletons of TPC fabricated by the additive manufacturing process named suspension‐enclosing projection‐stereolithography (SEPS) contain various kinds of microstructural features. This paper develops a two‐scale model consisting of micrometer‐scale ceramic particle level and millimeter‐scale composite level to systematically evaluate the effects of key microstructure features (e.g., micro‐porosity) and various topologies of TPC piezocomposites on their piezoelectric responses. Design maps for hydrostatic piezoelectric charging coefficients d _h show they can achieve optimal performance at wide ranges of micro‐porosity and geometry parameter u for the proposed TPC piezocomposites. In addition, geometry parameter u plays a dominant role in determining the intensity of hydrostatic voltage coefficient g _h and hydrostatic figure of merit (HFOM) of all the presented TPC piezocomposites in the vicinity of the starting point of three‐dimensional (3D) interconnectivity. Within this range, these properties would increase first with the increase of micro‐porosity volume fraction (VF) and start to decrease once they reach peak values. The presented TPC piezocomposites exhibit superb hydrostatic properties, with the same 20% VF of ceramics and 2% VF of micro‐porosity with respect to composites and ceramics, respectively; TPC of face‐centered cubic (FCC) demonstrates 327‐fold enhancement of HFOM than that of the piezocomposite with three intersecting ceramic cuboids. The piezoelectric properties of FCC are superior to those of body‐centered cubic (BCC) and simple cubic (SC). These findings present a promising approach for designing additively manufactured TPC piezocomposites to achieve superb hydrostatic performances.