Choi Myung-Jin, Oh Myung-Hoon, Koo Bonyong, Cho Seonho
Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
School of Mechanical Convergence System Engineering, Gunsan National University, Kunsan, 54150, Korea.
Sci Rep. 2019 Jul 10;9(1):9976. doi: 10.1038/s41598-019-46089-9.
This paper presents very large complete band gaps at low audible frequency ranges tailored by gradient-based design optimizations of periodic two- and three-dimensional lattices. From the given various lattice topologies, we proceed to create and enlarge band gap properties through controlling neutral axis configuration and cross-section thickness of beam structures, while retaining the periodicity and size of the unit cell. Beam neutral axis configuration and cross-section thickness are parameterized by higher order B-spline basis functions within the isogeometric analysis framework, and controlled by an optimization algorithm using adjoint sensitivity. Our optimal curved designs show much more enhanced wave attenuation properties at audible low frequency region than previously reported straight or simple undulated geometries. Results of harmonic response analyses of beam structures consisting of a number of unit cells demonstrate the validity of the optimal designs. A plane wave propagation in infinite periodic lattice is analyzed within a unit cell using the Bloch periodic boundary condition.
本文展示了通过对二维和三维周期性晶格进行基于梯度的设计优化，在低可听频率范围内实现的非常大的完全带隙。从给定的各种晶格拓扑结构出发，我们通过控制梁结构的中性轴配置和横截面厚度来创建和扩大带隙特性，同时保持晶胞的周期性和尺寸。在等几何分析框架内，梁的中性轴配置和横截面厚度由高阶B样条基函数参数化，并通过使用伴随灵敏度的优化算法进行控制。我们的最优曲线设计在可听低频区域显示出比先前报道的直线或简单波浪形几何结构更强的波衰减特性。由多个晶胞组成的梁结构的谐波响应分析结果证明了最优设计的有效性。使用布洛赫周期边界条件在一个晶胞内分析无限周期晶格中的平面波传播。
