A novel theoretical and computational framework to quantify dielectric relaxation effects on lamb waves in piezocomposites

Abstract

Dielectric relaxation is a widespread physical phenomenon that results in the dielectric coefficient taking on complex values, with both the real and imaginary parts changing in response to variations in frequency and temperature. It is evident that dielectric relaxation affects the dynamic performance of piezoelectric acoustic devices. However, research on this topic remains limited. In this paper, a theoretical framework based on the Debye/Cole-Cole models and continuum mechanics is developed to investigate the effect of dielectric relaxation on wave motion in piezocomposites. This framework describes the wave phase velocity changes and attenuation characteristics caused by dielectric relaxation across multiple scales and at varying temperatures. To quantify the impact, an accurate calculation is performed using a novel numerical method called Multidimensional Moduli Ratio Convergence (MMRC), which features a new root-discriminating mechanism and employs a two-dimensional (2D) root-finding approach to ensure efficient and robust solutions. A three-dimensional (3D) complex dispersion curve is obtained, revealing the propagation and attenuation characteristics of the wave. Six different wave mode shapes (Bending, Tensile, Thickness Tensile, and the first, second, and third Thickness Shear) in symmetric and antisymmetric modes are identified, and their attenuation effects are determined. Further investigation reveals the impact of frequency and temperature variations on the phase velocity and attenuation of the wave. This work is crucial for improving the performance of piezoelectric devices, particularly in terms of attenuation and frequency drift control.