三角阵列超材料的声传播特性

为了使声波产生不同于传统天然声学材料的反常传输特性，采用COMSOL有限元方法模拟了声波在局域共振型声子晶体中的传播特性，给出了二维三组元局域共振型声子晶体的振动机制，并以原胞为基础构建了三角形阵列的声学超材料模型，探究声波与该模型内原胞间的局域共振特性。仿真结果表明，从三角阵列模型底边入射的平面点状及线状激励声源在受到模型的调控后都会重新在顶角处汇聚成焦点；通过入射由三角阵列构成的矩形模型能实现点源的低损耗搬移效果；将两至三个相同的三角阵列组合成平行四边形和梯形模型后会产生平面声波的变向传输。模拟结果显示，此种以原胞为基础的三角形声学超材料阵列模型，在共振频率下会产生反常声学现象，并且随着模型构造的改变，其共振特性也会随之变化，产生不同的反常声学现象。研究结果可为声隐身、声探测及声波低损耗定向传输等研究提供新思路。

Acoustic propagation properties of triangle array metamaterials

To make acoustic wave produce abnormal transmission characteristics which are different from traditional natural acoustic materials, COMSOL finite element method is used to simulate the propagation characteristics of acoustic wave in local resonant phonon crystals.The vibration mechanism of 2D three-component locally resonant phononic crystals is given, and the acoustic metamaterials model of triangular array is constructed on the basis of cellular, to explore the local resonance characteristics between acoustic waves and cellular within the model. The simulation results show that the planar point and linear excitation source which is incident from the bottom edge of the triangular array model would be refocused at the top angle after being regulated by the model; the low-loss moving effect of point source could be achieved by incident rectangular model composed of triangular array; when two or three identical triangular arrays are combined into a parallelogram and a trapezoid model, the plane sound waves would be transformed to transmit. The simulation results show that this kind of triangle-based acoustic metamaterial array model will produce abnormal acoustic phenomenon under the resonance frequency, and the resonance characteristics will also change with the change of model construction, resulting in different abnormal acoustic phenomenon. The results can provide new ideas for acoustic stealth, acoustic detection and directional transmission with low acoustic loss.