Sanders Clay, Aquino Wilkins, Walsh Timothy
Department of Civil and Environmental Engineering, Duke University, Durham, North Carolina 27708, USA.
Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
J Acoust Soc Am. 2018 Jan;143(1):EL31. doi: 10.1121/1.5019699.
This letter demonstrates the design of continuously graded elastic cylinders to achieve passive cloaking from harmonic acoustic excitation, both at single frequencies and over extended bandwidths. The constitutive parameters in a multilayered, constant-density cylinder are selected in a partial differential equation-constrained optimization problem, such that the residual between the pressure field from an unobstructed spreading wave in a fluid and the pressure field produced by the cylindrical inclusion is minimized. The radial variation in bulk modulus appears fundamental to the cloaking behavior, while the shear modulus distribution plays a secondary role. Such structures could be realized with functionally-graded elastic materials.
这封信展示了连续渐变弹性圆柱体的设计，以实现对谐波声激励的被动隐身，无论是在单频还是在扩展带宽上。在一个多层、恒定密度圆柱体中，本构参数是在一个偏微分方程约束的优化问题中选择的，使得流体中无阻碍传播波的压力场与圆柱形内含物产生的压力场之间的残余最小化。体积模量的径向变化似乎是隐身行为的基础，而剪切模量分布起次要作用。这种结构可以用功能梯度弹性材料来实现。
