Hassan Scott E
NAVSEA Newport, Newport, Rhode Island 02841-5047, USA.
J Acoust Soc Am. 2007 Jul;122(1):237-46. doi: 10.1121/1.2735104.
An integral transform technique is used to develop a general solution for the impedance of rigid pistons acting on a two-layer medium. The medium consists of a semi-infinite acoustic fluid on a viscoelastic thick plate in a rigid infinite baffle. The stresses acting on the planar baffle, as a result of piston motion, are determined using theory of linear elasticity and are therefore unrestricted in terms of applicable frequency range. The special case of a circular piston is considered and expressions for the self-and mutual impedances are developed and evaluated numerically. Numerical results are compared with classical piston impedance functions and finite-element model results. At low frequencies (k(0)a<1), the self-impedances vary significantly from the classical piston impedance functions due to the shear properties of the viscoelastic medium. In the midfrequency range (1<k(0)a<pi) the self-impedances vary from the classical piston impedance functions for moderate viscoelastic layer thicknesses (0.5<ha<2). The mutual impedances associated with pistons on a two-layer medium generally exhibit an increased decay, as a function of separation distance, over the classical results.
采用积分变换技术来推导作用于双层介质上的刚性活塞阻抗的一般解。该介质由刚性无限障板中粘弹性厚板上的半无限声流体组成。根据线性弹性理论确定由于活塞运动作用在平面障板上的应力,因此在适用频率范围内不受限制。考虑圆形活塞的特殊情况,推导出自阻抗和互阻抗的表达式并进行数值评估。将数值结果与经典活塞阻抗函数和有限元模型结果进行比较。在低频(k(0)a<1)时,由于粘弹性介质的剪切特性,自阻抗与经典活塞阻抗函数有显著差异。在中频范围(1<k(0)a<pi)内,对于中等厚度的粘弹性层(0.5<ha<2),自阻抗与经典活塞阻抗函数不同。与双层介质上活塞相关的互阻抗通常在分离距离方面比经典结果表现出更大的衰减。