含包覆层型局域共振声子晶体的带隙特性研究OA

Low-frequency vibration and noise reduction of civil aircraft is a practical problem that needs to be solved urgently,and the local resonant phononic crystal with coating has excellent low-frequency noise reduction performance.Mastering the bandgap characteristics is a critical step in solving the problem.Based on the basic model of single cladding phononic crystal,the energy band structure of double cladding phononic crystal under the same working condition is analyzed.The modal analysis of the upper and lower boundary of the band gap is carried out.The reason of the low frequency band gap in the double cladding layer is discussed.The influence of structure parameters on the band gap of the coated phononic crystal is further studied.It is found that with the increase of the thickness of the cladding layer,the overall band gap moves to low frequency,the number of band gaps increases,and the bandwidth changes little.For double cladding phononic crystals,with the increase of the ratio of the outer cladding thickness to the inner cladding thickness,the band gap moves to the low frequency,the initial frequency of the first band gap gradually decreases,the bandwidth gradually decreases,and the second band gap gradually opens,and increases with the increase of the thickness ratio.The results of this paper will provide some theoretical guidance for practical engineering application.