摘要:

The limit of a vanishing shear modulus in the null‐field approach to elastodynamic scattering by bounded scatterers is investigated. It is demonstrated, for a fairly large class of surfaces and for several types of boundary conditions, that the coupling between the incident and scatteredPwaves tends to that of a corresponding acoustic scattering problem. However, by explicit examples it is also demonstrated that theP–Scoupling does not in general tend to zero rapidly enough for the amplitude of the scatteredSwave to vanish pointwise in this limit; there remains a nonzero amplitude of a wave whose wavelength goes to zero.

ISSN:0001-4966    

DOI:10.1121/1.394149

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

Experimental studies on the reflection and transmission of bounded acoustic beams at a liquid–solid plate–liquid interface show that, for incidences at or near the Lamb angles, some effects occur which are similar to those reported at a liquid–solid interface for the Rayleigh incidence. Theoretical descriptions of this phenomenon have been proposed that are based upon asymptotic considerations for the reflected beam and numerical considerations for the reflected and the transmitted beams. These previous theories are extended in this work. The reflected and transmitted Gaussian beams are described through a short wave asymptotic analysis in regions which are not restricted to the interfaces. The nonspecular effects which appear in the transmitted field composition are different according to whether the Lamb mode under consideration is symmetric or antisymmetric. The particular case when two Lamb modes are simultaneously excited is also studied. If the two modes have a different nature, the nonspecular effects are added while, for two modes of same nature (symmetric or antisymmetric), this is no longer true.

ISSN:0001-4966    

DOI:10.1121/1.394150

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

A multiple scattering formalism using aTmatrix to characterize the response of a single fiber to an incident wave is presented to describeP‐ andSV‐wave propagation in a fiber‐reinforced composite. A convenient numerical procedure is then developed to compute the effective elastic moduli, attenuation, and phase velocity as a function of frequency and fiber concentration.

ISSN:0001-4966    

DOI:10.1121/1.394151

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

The transmission, reflection, and interaction of linear, one‐dimensional acoustic and entropy waves within subsonic, quasi‐one‐dimensional, finite length gas flows is considered. A numerical analysis is used to relate the time variations in gas properties along the length of the duct. Appropriate equations are derived for the case of a nonviscous, nonheat‐conducting, fixed composition, ideal gas with constant specific heats and no external body forces or energy sources, though the general procedure may be applied to more complicated flows. The results are expressed in terms of nine frequency‐dependent reflection and transmission coefficients. To demonstrate the analysis, calculations are presented for a 4:1 area ratio, 1‐m‐length nozzle and for a 1:4 area ratio, 1‐m‐length diffuser.

ISSN:0001-4966    

DOI:10.1121/1.394153

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

The two‐microphone transfer function method for impedance tube measurements has been extended to include the effect of the tube attenuation.

ISSN:0001-4966    

DOI:10.1121/1.394154

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

摘要:

It is noted that a simple form of the method utilized by Lauraetal., ‘‘A modification of the Galerkin method and the solution of the Helmholtz equation in regions of complicated boundary shape’’ [J. Acoust. Soc. Am.77, 1960–1962 (1985)] has already appeared in Rayleigh’s classical treatise on the theory of sound [J. W. S. Rayleigh,TheTheoryofSound, Vol. I (Dover, New York, 1945)].

ISSN:0001-4966    

DOI:10.1121/1.394155

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.394157

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.394125

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.394126

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.394127

出版商:Acoustical Society of America    

年代:1986

数据来源: AIP