• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue

Jun 1977

Volume 61, Issue S1, pp. S1-S96

Return to All Sections
back to top
RSS Feeds
back to top Session E. Shock and Vibration I: Machinery Noise and Vibration Monitoring
Invited Papers
FREE

Proposed shipboard noise and vibration monitoring system (A)

Adamandios G. Gafos

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S9-S9 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
In this paper the composition, operation, and performance capabilities of a shipboard noise and vibration monitoring system will be described. The uniqueness of this system is that it consists of readily available off‐the‐shelf instrumentation designed to measure or monitor both the mechanical and/or acoustic condition of shipboard machinery. For this particular application the system has been tailored for use aboard a new class of Navy ships.
FREE

Velocity as vibration for measurand machinery condition analysis (A)

R. F. Misialek

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S9-S9 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
The paper presents the argument for using vibration velocity rather than acceleration or displacement as the measurand to more readily assess rotating machinery health and maintenance requirements. Also presented are the techniques used and the inherent advantages.
FREE

Signal processing for a shipborne noise and vibration monitoring system (A)

D. W. Hackett and G. A. Hirschfield

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S9-S10 (1977); (2 pages)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
OTI has developed and is producing a shipboard signal processor for interfacing noise and vibration sensor signals with a digital computer and narrow‐band spectrum analyzer. The Monitoring System Signal Processor (MSSP) provides for 144 accelerometer and 6 hydrophone inputs, as well as A/D rand D/A conversions of auxiliary dc, ac, and discrete signals. The MSSP scans the input channels and conditions the incoming signals which are then fed through a bandpass filter and selector. The selected band is connected to a variable gain amplifier. The scaled analog data are low‐pass filtered, sampled, and converted to digital format. A block of 2048 digital samples are then stored and block transferred to the computer. The computer transfers the data to a separate spectrum analyzer for narrow‐band frequency conversion and ⅓ octave band generation. The computer provides for storage of threshold values for various ship speed ranges, and generates alarms and displays for operator action when these limits are exceeded. The system can be reconfigured to incorporate the frequency transform function into the MSSP. In conjunction with a small computer and suitable peripheral equipment this would comprise a compact NVM system for shipboard or industrial applications. [Work supported by NAVSEA and NAVSEC under Contract N00024‐75‐C‐7217.]
Contributed Papers
FREE

Frequency, amplitude, and load effects on the dynamic properties of elastomers (A)

John E. Cole, III

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S10-S10 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
The dynamical‐mechanical properties of elastomer materials, which are widely used in devices such as antivibration mounts, are known to depend upon the nature of the loading of the material. While many aspects of the dependence of the dynamic properties on frequency and temperature are well known and customarily accounted for, these properties are also known to vary significantly with other aspects of the loading such as strain amplitude and static load. Furthermore, not all of these aspects of the loading appear to act independently. In this paper we discuss the dependence of the dynamic properties of elastomers on frequency, dynamic strain amplitude, and static loading. While the effects of frequency and strain amplitude appear to be separable, it does not appear to be as easy to deal with the effects of static loading. The implications of these effects on designs using elastomers is discussed. [Sponsored by USN Office of Naval Research—Structural Mechanics Program.]
FREE

Improved lower bounds for fundamental frequencies of beams (A)

S. Hanna and C. D. Michalopoulos

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S10-S10 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
Lower bounds for buckling loads and fundamental frequencies of elastic bodies have been developed recently from energy considerations. In general, these bounds are very simple to calculate but they lack the accuracy of upper bounds. In this paper, an improved lower bound is obtained. Numerical results are presented to demonstrate the improvement on existing lower bounds. The method is specifically applied to determine a lower bound to the fundamental frequency of nonuniformly compressed beams. Comparison is made of these results with those obtained by other methods. [Work supported in part by NASA.]
FREE

Dynamic stability of nonuniformly compressed beams (A)

S. Hanna and C. D. Michalopoulos

J. Acoust. Soc. Am. Volume 61, Issue S1, pp. S10-S10 (1977); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
The boundaries of the principal region of instability and upper bounds of natural frequencies of a nonuniformly compressed beam are determined approximately using the free‐vibration eigenfunctions of the uncompressed beam with the same boundary conditions. Specifically, beams under distributed compression, such as the beam's weight, and beams subjected to multiple concentrated loads are considered. Numerical results are given for beams having hinged‐hinged, fixed‐hinged, free‐free, and fixed‐free end conditions. [Work supported in part by NASA.]
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close