About the Journal :
In the present paper, we focus on the ability of phononic crystals to treat the different elastic wave's frequencies at the same structure. Changing the periodicity of the structure from perfect and defect structure can modify the width/position of phononic band gaps. By comparing between one, two and four defect layers inside perfect ones, interesting results concerning the localized peaks with the band gaps were obtained. Since the width of band gaps and the number of localized peaks are increased by increasing the defect layers. Moreover, we pay more attention in comparing the band gaps between periodic and quasi-periodic structures. A multifunctional PnC structure could be obtained depend on periodicity and materials types were investigated and discussed. These results may be of potential importance in many engineering applications such as mechanical filters and vibration isolation devices.
Keywords: Phononic band gap; Defects; Crystal.