Abstract: Based on the vibrational equation of the thin plate, the band structure for the two-dimensional phononic crystals thin plate composed of two kind of material is provided by using plane wave expansion method. The composite materials thin plate exhibiting vibration band gap is found. But it is different from the xy mode band structure of two-dimensional phononic crystals. For the finite periodic structure thin plate, the vibration frequency response by finite element method is simulated. The frequency ranges of sharp drop in frequency response curve show good agreement with the band gaps. The wave field dis-tribution of the frequency both in band gap and out of band gap is calculated in order to describe the vibration property of the phononic crystal thin plate. The existence of band gaps in the periodic structures thin plate gives a new idea in vibration control application of phononic crystals.

Key words: Phononic crystals, Thin plate, Vibration band gap