Enhancing thermo-electro-mechanical properties of piezoelectric fiber-polymer composites via boron nitride nanotube addition: A predictive micromechanical model

Abstract

The intra-matrix incorporation of boron nitride nanotubes (BNNTs), due to their superior mechanical properties, thermal stability, and electrical characteristics, can serve as an infrastructure for cutting-edge implementations of piezoelectric fiber-reinforced composites (PFRCs). This micromechanical investigation systematically elucidates the role of BNNTs in enhancing the thermo-electro-mechanical properties of hybrid piezoelectric systems. In this context, the effective properties of BNNT-polymer building blocks are extracted by accounting for microstructural interactions, notably the agglomeration behavior of randomly dispersed BNNTs. Subsequently, by introducing and refining the structural relations governing the material system, the responsive nature of appropriate representative volume elements is rigorously evaluated through an extended isofield micromechanical framework, specifically tailored to address the identified requirements. Following validation of the developed model against available literature, a comprehensive evaluation is conducted to assess the effects of BNNT content, agglomeration behavior, and nanotube diameter on the elastic stiffness, thermal expansion, thermal stress, and piezoelectric constants of BNNT-filled PFRC system. Furthermore, the influence of BNNT diameter on the effective properties is systematically evaluated, revealing its critical role in tailoring thermo-electro-mechanical performance. This approach lays a robust foundation for optimization, thereby eliminating the necessity for exhaustive and time-consuming parametric analyses. © 2025 The Author(s)