Ultrawide band gap design of phononic crystals based on topological optimization

In this paper, based on the combined finite element method and bidirectional evolutionary structural optimization algorithm, we perform the topological optimization of phononic crystals to obtain ultrawide band gap between two special adjacent bands for both the in-plane and out-of-plane wave modes. The influences of matrix/scatter materials, material volume fraction, and initial topological design on the unit cell optimization are discussed in detail. The results show that the strategy proposed in this paper is effective and efficient to obtain better optimization results under the similar optimization condition, solutions with ultrawide band gaps can be easily obtained within 30 iterations. Several new patterns for phononic band gap crystals with optimized band gaps are presented. This work provides useful guidance in topological optimization design of phononic crystals.