Sound Transmission through a Finite, Closed, Cylindrical Shell

Abstract

The transmission of an acoustic wave through an infinite, homogeneous, isotropic cylinder has been derived to be a strong function of frequency and the angle of incidence between the axis of the cylinder and the incoming wave. From this analysis, two important characteristics are found: the ring frequency, where the wavelength of a longitudinal wave in the material is equal to the circumference, and the coincidence frequency, where the trace wavelength of the incident wave is equal to the bending wavelength in the shell wall. The transmission loss will take on minimum values at these two points. Measurements with 13-oct-band noise excitation of a closed cylindrical shell with l/d=1.5 show the same gross features to be present and with additional effects of low-frequency resonances, but with very little angular dependence. The presence of stiffening corrugations and irregularities in the shell leads to a random vibration field and allows methods developed for the transmission of random sound through flat panels to be successfully used for noise-reduction estimates.

Acoustic Transmission Through Cylindrical Shells Treated with FLD Mechanisms

“…The displacement vector X can be defined as: (8) where u, v, w are displacements of the shell respectively in the axial, radial and circumferential directions. The displacement vector X can be defined as: (8) where u, v, w are displacements of the shell respectively in the axial, radial and circumferential directions.…”

“…Noise transmission, measured by transmission loss (TL) through the circular shell, has been studied by Smith [7], White [8], Koval [9,10], Blaise et al [11] and Kim [12] for isotropic, orthotropic, and laminated fiber-reinforced composite shells. student bration and acoustic media.…”

Design and Optimization of Sensitivity Enhancement Package for MEMS-Based Thermal Acoustic Particle Velocity Sensor

“…Another problem occurring while packaging TAPVS in a protection skin is that even if the sound-transmitting material is used, the transmission loss [ 26 , 27 , 28 , 29 ] of the sound signal is inevitable, which will seriously influence the sensitivity of TAPVS. Therefore, it is necessary to develop an effective protocol to maintain its high sensitivity while TAPVS is protected by sealing covering.…”

Mathematical model for characterizing noise transmission into finite cylindrical structures

“…Tang et al studied an infinite cylindrical sandwich shell with honeycomb core. 6,7 A simplified analysis of sound transmission through a finite, closed cylindrical shell was first proposed by White, 8 while the sound radiation into the acoustic cavity enclosed by a finite cylindrical shell with end plates was studied by Cheng. 9 Tso and Hansen derived a coupling loss factor for a cylindrical/plate structure using statistical energy analysis, 10 their method, however, does not work well at low frequencies and further could not show the effects on sound transmission of the cavity resonances.…”

“…fluid particle acceleration at boundary ( r = a ), which is equal to the normal rigid surface acceleration, and ( particle acceleration at the boundary. This acceleration is given by wave equation(8) or boundary condition Eq (9). …”