The Research On Transimitted Property Of Lamb Wave In Phononic Crystals

Mechanical vibration is widely present in national defense and military, aerospace,mechanical power, transport and other fields,suppression of harmful vibration has been a pressing need to solve the problem of engineering technology. Platform for large-scale industrial equipment,industrial production of harmful vibration is one of the security risk. At present, the way to isolate the vibration' transmission, using a number of isolation techniques,allowing the vibration of the carrier has been to a larger reduction, but the low frequency vibration isolation is still the difficulty of vibration technology. As the high-frequency noise in the structure with the propagation distance decay quickly, while the low-frequency noise attenuation with distance is a lesser degree, and thus low-frequency vibration isolation become an urgent need problem to solve. If the structure of the low-frequency noise, or air noise can be isolated effectively in a variety of engineering and technical fields,that will be of great significance. Artificial periodic structure of materials research provide a new way of thinking for the settlement of this issue.Materials or structures with the existence of elastic wave band gaps,elastic constants and density cycle distributionare called phononic crystals,in which elastic wave propagatting the band gap will to be generated,the elastic wave transmission are prohibited within the band gap.In this paper, phononic crystal as to be the research object, we made researchs on Lamb wave among the phononic crystal based on numerical analysis,simulation analysis of the energy spectral density diagram.This paper mainly carried out and completed the following research work:1.Finite element analysis of energy spectrum in one-dimensional Lamb wave and two-dimensional Lamb wave phononic crystals;2.Study on characteristics of Lamb waves propagation in phononic crystals based on the ternary structure of the one-dimensional quasi-periodic Fibonacci sequence structure model;3.Study on characteristics of Lamb waves propagation in the sheet metal plate of periodic structure with the cross-sectional area linear changing and on the Lamb waves energy spectrum in the periodic structure of the functionally graded plate;4.Do the experiment for Lamb-waves in the periodic plate and study on the dispersions of Lamb wave.The Lamb wave phononic crystals properties can be analysed by means of commercial finite element software and experiment.Research shows that phononic crystals is of great practical significance for sound insulation, noise reduction and other projects and the Lamb wave phononic crystals in nondestructive testing has potential applications.