摘要:

By considering the boundary value problem in Lagrangian coordinates it is shown that there should be no generation of fractional harmonics in a fluid‐filled resonant cavity when the parameter of nonlinearity of the fluid (1+B/2A) is zero. It is proposed that the mathematical model of Adler and Breazeale, which is independent of 1+B/2A, be made consistent with this result by taking into account the variation in the mean density of the fluid which accompanies the periodic change in the length of the cavity.

ISSN:0001-4966    

DOI:10.1121/1.1913107

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Acoustic ray deflection by aircraft wake vortex flows has been observed during landing operations of large aircraft. The phenomenon has been used to detect and locate vortex traces in a plane perpendicular to the runway centerline. The maximum deflection angles observed for a variety of aircraft show qualitative agreement with values predicted for a viscous core.

ISSN:0001-4966    

DOI:10.1121/1.1913108

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

In a recent paper, Freedman investigated the farfield time‐dependent pressures radiated from a rectangular piston with a pulsed velocity. Subject to specified bandwidth assumptions on the velocity, the resulting pressures in the farfield were shown to consist of replica pulses of the velocity. A comparison of Freedman's results with the results obtained from an alternate approach which requires no bandwidth assumptions is presented here. Although the pressure results from both approaches are in agreement in the principal planes of the piston, the exact approach shows the pressures at other points in the field are related to the piston displacement rather than the velocity. Since the farfield pressures resulting from a pulsed velocity can be expressed as a sum of pulses which are proportional to the piston displacement, significant differences in the numerical results obtained using Freedman's approach and the exact approach are noted.

ISSN:0001-4966    

DOI:10.1121/1.1913109

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The relationship between theimpulse response functionapproach and thereplica pulseapproach is clarified.

ISSN:0001-4966    

DOI:10.1121/1.1913110

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

A nonlinear mathematical model of the dynamics of an extensible cable in a uniform flow field is used to study the degree of coupling between longitudinal and transverse modes of motion. The various coupling effects are elucidated, and through use of numerical solutions of the model, the primary coupling effect is shown to be the tension variation due to centripetal acceleration of the cable.

ISSN:0001-4966    

DOI:10.1121/1.1913111

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

An analysis is presented for obtaining the steady‐state response of infinitely long elastic cylindrical shells subjected to a concentrated radial load. The effects of a small amount of internal material damping are included. The Fourier integral transform and series solution technique are employed for determining the solutions of the governing equations. Numerical results of a steel long shell to a concentrated radial load are presented.

ISSN:0001-4966    

DOI:10.1121/1.1913112

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

An analysis of the vibration of slightly curved Bernoulli‐Euler beams, which have constant initial curvature, is presented. A closed form general solution to the governing equation is derived, and the natural frequency, as it is affected by curvature and the type of end fixity, is discussed, with results given for the first three modes.

ISSN:0001-4966    

DOI:10.1121/1.1913113

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The problem examined is the steady‐state response of a single‐degree‐of‐freedom system subjected to repeated impact at equal intervals of time. Transmissibility curves for various damping, plotted as a function of the frequency ratio, are presented.

ISSN:0001-4966    

DOI:10.1121/1.1913114

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Solutions for the free vibration of anisotropic plates with other than clamped edge conditions have been previously obtained by approximate energy methods in conjunction with classical beam mode functions. Because of the existence of cross‐elasticity bending stiffness terms, however, the beam functions do not satisfy the natural boundary conditions. Numerical results presented for a simple supported anisotropic plate indicate that such an approach yields very slow convergence of the vibration frequencies for highly anisotropic materials, such as graphite‐epoxy fiber reinforced composites. Improved results are obtained by using a classical Fourier analysis in which both the geometric and natural boundary conditions are satisfied.

ISSN:0001-4966    

DOI:10.1121/1.1913115

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The absorption of sound in the Pacific Ocean, at a nominal frequency of 75 kHz, was measured over a horizontal path at depths of 910 and 3350 m. The results are 20.0±1.5 dB/km and 13.5±1.5 dB/km, respectively, which may be compared to values of 27.3 dB/km and 22.7 dB/km extrapolated from the empirical relation of Schulkin and Marsh. Evidently, the useful range of this relation is severely limited. In addition, the effect of pressure may be greater than previously suspected.

ISSN:0001-4966    

DOI:10.1121/1.1913116

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP