Band gap manipulation on P-wave propagating in functionally graded phononic crystal by periodical thermal field

Phononic crystals and acoustic metamaterials have attracted many researchers by reason of unconventional acoustic behaviors which can be applied to achieve wave propagation control. To enhance the application value of acoustic behaviors, period structures with adaptive control ability have been an investigation focus. In the present paper, an innovative manipulation method based on inhomogeneous and periodic thermal field for longitudinal wave (P-wave) band gap control is proposed and investigated. A three-dimensional solid model, consist of homogeneous thermal sensitive material, can be transferred into functionally graded phononic crystals by a series of metallic films which are periodically embedded in structure and play the role of heat sources. Based on laminated model and transfer matrix method, propagation characteristics of both normal incident and oblique incident P-wave in functionally graded crystals are investigated. Numerical band structure results from analytical method, validated by simulation result via COMSOL Multiphysics software and transmission spectra result, reveal that period thermal field owns the ability to affectively tune the band gap properties including band width and band gap location. Also, transmission spectra result indicates that the attenuation of wave propagation may be inconspicuous even there exists obvious but relatively narrow stop band gaps. The present research proposes a band gap tuning method on P-wave according to the application of period thermal field and may lay theoretical and simulation foundation for designing and fabrication of tunable vibration isolators and acoustic filters.