Abstract: The double cladding layer local resonance mechanism resonators in phononic crystal was proposed .The band gap formation mechanisms , the width of band gap affect factors , and sound insulation quantities with finite element methods were analyzed .These results show that starting frequency depends on higher elastic modulus of the double cladding layer elasticity , cut-off frequency depends on smaller bulk density of elasticity .These results that phononic crystal has a good the light quality , low-frequency , width band gap and the sound insulation of characteristics , provides potential applications prospect the reducing of low-frequency noise in the mechanical equipments and provides theoretical guidance for the design of the structure of the phonon crystal .

Key words: phononic crystal;local resonance;band-gap mechanism;sound insulation of characteristic