ICSV26

It has been shown that the bandgaps of porous phononic crystals can be effectively tuned by the post-buckling deformations triggered by external stimulus, e.g. mechanical loadings, electric fields, and magnetic fields etc. However, controlling of the post-buckling deformation is sometimes not robust due to its sensitivity to geometry imperfections. In this work, a phononic crystal plate made of soft material with spring-mass-like resonant units which are connected to the perforated plate by thin beams, is proposed to tune the band gaps through small deformations instead of large post-buckling deformation. Finite element method is employed to study the deformation and the dispersion behavior of such structure when subject to external mechanical loadings. Obvious complete band gaps are found to even exist in the intact structure without any mechanical loading. The evolution of band gaps under stretching is systematically revealed. Results show that remarkable tunability of bandgaps with small pre-stretch or extension is realized when strong resonance appears for some particular modes. The resonance frequency is mainly affected by the mass of the resonator and the stiffness of the connecting beams. In the proposed structure, the stiffness of the connecting beams can be substantially increased under a small pre-stretch. As a result, the resonance frequencies of resonant modes are increased, giving rise to a remarkable modification of the band gaps, while the geometry of the structure is nearly unchanged.