Topological design of 2D phononic bandgap crystals with the six-fold symmetry or the reduced symmetry

Phononic crystals are novel artificial periodical materials which exhibit phononic bandgaps preventing the propagation of acoustic or elastic waves in a particular frequency range. Zhaoxuan Zhang investigates the topology optimization of two-dimensional solid phononic crystals for maximizing specified bandgaps with different lattices and symmetries based on the bi-directional evolutionary structural optimization method. The research exhibits many novel patterns with large band gaps for different wave modes and systematically discusses the influences of lattice type and symmetry on phononic bandgap size. The efficiency and ability in opening wide bandgaps of the proposed gradient-based BESO method has also been proved.