Design framework for phononic crystals based on compression-twist coupling structures with curved beams

Abstract

Compression-twist coupling structures (C-TCSs) with curved beams (CBs) exhibit unusual static and dynamic mechanical behaviours, leading great application potentials for massive engineering structures including metamaterials. Specially, the acoustic metamaterials or phononic crystals (PCs) featured by C-TCSs present outstanding bandgap properties (such as tuneable central-position and width of bandgaps adjusted via the geometry of the CBs) than those from traditional designs, endowed with numerous applications with respect of vibration and wave control fields. This paper proposes a C-TCS connected by CBs for super coupling effect and specified bandgap behaviour when treated as PCs. To investigate the performance of the C-TCS and the resulting PCs, isogeometry analysis and finite element method are adopted. A design and optimization framework with genetic algorithms is further established to search for the optimal geometry configuration of the C-TCSs. Our results show that the refined C-TCSs with CBs enhance significantly the coupling performance. And the redesigned PCs, especially those with gradient unit cells, present advanced capabilities of low-frequency, large width and prescribed bandgaps. The proposal creates a new way to the design of novel acoustic metamaterials.