ANALYSIS OF BAND GAP STRUCTURES OF THERMAL WAVE IN FUNCTIONALLY GRADED THERMOELECTRIC PHONONIC CRYSTALS

This study presents a novel investigation of thermal wave propagation in layered phononic crystals (PCs) composed of functionally graded materials (FGMs), revealing unprecedented thermal band gap tuning mechanisms through the Cattaneo–Vernotte and dual-phase-lag heat conduction models. Unlike conventional homogeneous PCs, the FGM-based structure introduces unique gradient-dependent band gap modulation, analyzed via the transfer matrix method and Bloch theorem. The complex dispersion curves of thermal waves are obtained. The first band gap intervals increase with the increase of the gradient change index ₀, and the intervals of the first band gap shrink and then become broader a little bit with the increase of parameter. Besides, the first band gap intervals decrease with the increase of. The intervals of the first band gap increase with the increase of C_ρn. The τ_qn can affect the first band gap width and the number of the band gap.