摘要:

Rayleigh waves, which are elastic surface waves occurring at the interface between a solid elastic body and vacuum, are investigated. The exact solution of some canonical elastodynamic problems in a circular cylindrical geometry is given, from which the Rayleigh wave contribution is isolated. The dispersion—i.e., the dependence of the velocity of propagation of these waves on the local radius of curvature (of the interface)—is investigated. The propagation velocity diminishes as the ratio between wavelength and radius of curvature diminishes, reaching an asymptotic value at “zero wavelength.” A comparison is made with the small‐wavelength asymptotic approach of Keller and Karal, which does not take dispersion into account. It is found that the effects of dispersion should not be ignored down to rather small wavelengths. Moreover, it is found that there occurs a “critical” or “cutoff” wavelength, above which no proper Rayleigh wave can exist. Thus, a Rayleigh wave that propagates on an interface of variable curvature towards a point of minimum radius may be scattered and partially transformed into body waves.

ISSN:0001-4966    

DOI:10.1121/1.1911400

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The problem of the free vibrations of a thin orthotropic, oblate spheroidal shell has been solved by making the assumptions of orthotropic membrane theory and harmonic axisymmetric motion. The theory has reduced the differential equations of motion to a single ordinary second‐order differential equation with variable coefficients. The resulting eigenvalue problem is solved by Galerkin's method. The principal directions of the elastic compliances are assumed to be along parallels of latititude and along meridians. Both the oblate spheroidal and spherical shells were studied with various orthotropic constants. The existence of finite bounds for the corresponding mode shapes has been shown. Special consideration is given to the isotropic shell as a limiting case of the orthotropic problem. The present theory in the isotropic case yields the author's previously published results for the isotropic oblate spheroidal shell, as well as the known exact solution of the isotropic spherical shell.

ISSN:0001-4966    

DOI:10.1121/1.1911401

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Free, axisymmetric vibrations of thin elastic spherical shells submerged in a fluid are considered in this study. Irrotational motions in compressible and incompressible ideal fluids and motions in vacuum are compared via numerical examples given for steel shells vibrating in water. The results indicate that an incompressible fluid representation is applicable for the determination of natural frequencies for those modal shapes that exhibit both membrane and composite behaviors. Applicability of an incompressible solution for the uniform radial and first‐order membrane modes is dependent on the shell radius‐to‐thickness ratio. Also demonstrated is a change in modal characteristics imposed by a surrounding fluid that provides further insight into the nature of the fluid‐shell interaction.

ISSN:0001-4966    

DOI:10.1121/1.1911402

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The review in the reference cited above presents such a distorted and inadequate appraisal of the orientation and content of my textbook that I feel professionally obligated to provide areply. My primary comments are organized into two major categories: (1) those that deal with the reviewer's conception of the general organization and direction of thetextbook, and (2) those that concern the reviewer' remarks on specific content. This Letter is notintended to be an exhaustive and point‐by‐point reply to the reviewer' assertions, but is sufficiently directive to establish that the review grossly misrepresents thetextbook.

ISSN:0001-4966    

DOI:10.1121/1.1911403

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Auditory units in the eighth nerve of the leopard frog (Rana pipiens) are frequency selective with best frequencies from less than 100 Hz to near 2000 Hz. There are two distinct types of units, simple and complex. Simple units are most sensitive to high‐frequency tones, are usually spontaneous, and cannot be inhibited by sound. Complex units usually have best frequencies below 700 Hz and each can be inhibited by tones with frequencies above its best frequency. The primary auditory units of the leopard frog are similar to those found in the bullfrog and the green frog. A preliminary study of the spectral characteristics ofR. pipiensmating calls indicates that both types of units would be excited by these sounds. This suggests that mating‐call detection in the leopard frog may depend upon the excitation of simple and complex units, as it does in the bullfrog.

ISSN:0001-4966    

DOI:10.1121/1.1911405

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The justification for the term “Haas effect” is discussed.

ISSN:0001-4966    

DOI:10.1121/1.1911406

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Acoustic absorption measurements have been used to determine vibrational relaxation times in pure oxygen and in oxygen with up to 2% methane impurity at 25°C and 126°C. These measurements were undertaken to resolve the disagreement in the measurements reported by two other investigators of the same system. The results presented confirm the results reported by Schnaus [U. E. Schnaus, J. Acoust. Soc. Amer.37, 1–4 (1965)] and conflict with those reported by Parker and Swope [J. G. Parker and R. H. Swope, J. Chem. Phys.43, 4427–4434 (1965)].

ISSN:0001-4966    

DOI:10.1121/1.1911408

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The −π/2 phase jump predicted in Tolstoy's analysis for refracted waves passing through a caustic is also predicted, by an entirely different analytical technique, for the related situation of diffracted waves traversing a caustic specifically the caustic at the center of the shadow zone of a spherical scatterer. The phase jump is shown to be related to the cylindrical symmetry of the diffracted field.

ISSN:0001-4966    

DOI:10.1121/1.1911410

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1911411

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1911412

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP