Influence of the porosity and auxeticity of matrices and interfacial integrity on the performance of KNN-based piezocomposites

In the evolving field of sustainable piezoelectric materials, enhancing the functional performance of lead-free composites is critical for broader application in eco-friendly technologies. Building upon our prior computational analysis of phase connectivity in piezocomposites, this study delves into the specific roles of porosity, auxeticity, and interfacial integrity in optimizing the performance of a promising KNN-BNZH & Polyethylene composite. We combine numerical homogenization and analytical microstructural models to systematically investigate how these matrix characteristics influence the electromechanical properties across a range of applications, including sensing, actuation, and energy harvesting. Specifically, we study the functional performance through a comprehensive parametric analysis of various figures of merit. Our analysis considers both 0–3 and 1–3 connectivities with active phases in the form of spherical particles and cylindrical fibers. We have identified the conditions under which an increase in the volume fraction of the active phase enhances performance, as well as those under which it does not. Specifically, we have determined how the porosity and auxeticity of the matrix influence the peak figures of merit and their locations for each connectivity pattern. Additionally, we have assessed the effects of interfacial integrity between the matrix and inclusions, a critical factor in the overall performance of the piezocomposite. Our results show that electrical damage significantly impacts the electrical and piezoelectric properties, while purely mechanical damage has a lesser effect. Furthermore, the study emphasizes that the findings are based on numerical simulations and theoretical models, necessitating experimental validation to confirm these results and fully understand their practical implications and limitations. • Influence of various matrix characteristics —porosity, auxeticity, and matrix-inclusion interfacial integrity— on KNN based piezocomposites electromechanical performance in 0–3 and 1–3 patterns. • Porosity reduces stiffness and d-coefficients but can boost d 33 and Q h 2 in 1–3 configurations. • For 1–3 patterns, highly auxetic matrices lead to significant improvements in certain figures of merit, such as d 31 , k p , g, Q 31 2 , Q 33 2 , and Q h 2 . • Mechanical and electrical interfacial damage can significantly degrade the dielectric and piezoelectric properties. • In the 1–3 connectivity, certain properties and figures of merits show minimal changes with increasing interfacial damage, indicating some level of resilience.