Tuned broadband vibrational dissipator

Details Tuned broadband vibrational dissipator Tuned broadband vibrational dissipator

1999-02-25

2001-10-09

Oberleitner, Robert J. (Department: 3613)

Brakes

Inertia of damping mass dissipates motion

Resiliently supported damping mass

C267S136000

Reexamination Certificate

active

06298963

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to damping, more particularly to methods, apparatuses and systems for passively effectuating damping for controlling vibrations.
Vibrations are often unwanted because they can cause structural weakening, metal fatigue, bothersome noise, etc. Particularly undesirable are many situations wherein a power-driven source (e.g., a motor) produces a frequency at which an attached structure naturally vibrates, an occurrence known as “resonance.”
Various types of passive damping treatments have been known to be effective in reducing the amplitude of vibrations at resonant frequencies. The known effective passive damping methodologies include “conventional” damping, “entrained” damping and “tuned” damping.
Two known kinds of conventional damping treatment are unconstrained (unconstrained-layer) damping treatment and constrained-layer damping treatment. All of these known passive damping mechanisms, though often highly (or at least moderately) effective for particular applications, nonetheless have limited capabilities in terms of damping performance.
Tuned damping, for example, produces a relatively large loss factor in a narrow frequency band. Therefore, tuned damping is generally applied to reduce single mode vibration. In contrast, constrained-layer damping is effective in a broad frequency, but its loss factor is relatively small. Because of this, constrained-layer damping treatment is relatively effective for controlling the vibrations in higher frequencies, but is less effective in lower frequencies.
A greater amount of damping loss factor has been known to be achieved by applying an increased number of similar passive damping treatments on the structure; however, this sort of “pluralizing” approach to individual units yields a diminishing return in damping effectiveness as the amount of damping treatment (i.e., the number of units) increases.
Active (as distinguished from passive) vibration control methodologies have also been known to effectively reduce vibrations. However, due to limitations regarding processor speed and actuator power delivery, active vibration control has proven rather impractical in high frequency and multi-mode vibration control. Moreover, the costs associated with installation and maintenance of active vibration control systems, vis-a-vis' passive vibration control systems, are comparatively high.
Generally speaking, depending upon the application, a damping treatment is considered to be effective if the vibrational reduction caused by the damping treatment in turn results in a decrease in at least one of the following: sound radiation; structural stresses attendant fatigue problems in structural members; and, structural-borne wave propagations (i.e., the transmission of vibrational energy along the structure).
SUMMARY OF THE INVENTION
In view of the foregoing, it is a principal object of the present invention to provide a passive vibration damping methodology which is effective over a broad range of frequencies.
It is a further object of the present invention to provide such a methodology which is economical.
The passive vibration damping device according to this invention is conveniently identified herein by the acronym “TBVD” for “Tuned Broadband Vibrational Dissipator.” The inventive TBVD provides large loss factors in a broad frequency band. In typical inventive practice, the inventive TBVD is implemented as an add-on damping device.
In accordance with many embodiments of the present invention, the inventive TBVD is a device for effectuating passive vibration damping of a structure which is subject to excitation by a source. The inventive device comprises a viscoelastic layer, a hollow member and granular material. The viscoelastic layer adjoins the hollow member. The granular material at least partially fills the hollow member.
According to many inventive embodiments, the present invention provides a method for effectuating passive vibration damping of a structure which is subject to excitation by a source. The inventive method comprises: providing a hollow member; at least partially filling the hollow member with granular material; and, affixing a viscoelastic layer to the hollow member.
The present invention features a structural integration which affords multi-damping simultaneity. Inventively integrated are various structural components which, customarily, are separately utilized in furtherance of individually corresponding passive damping mechanisms. This inventive structural integration effectuates the synchronization of three passive damping mechanisms—viz., constrained-layer damping, entrained damping and tuned damping. The present invention thereby propitiously affords a cumulative damping effect which is the aggregation of the individual damping effects corresponding to the respective damping mechanisms.
Thus the present invention, unlike previous damping treatments, is designed to simultaneously operate a diverse plurality of damping mechanisms so as to produce a large loss factor in a broad frequency band. Moreover, the present invention provides multiple tuning capability which can be tailored to suppress multiple resonant modes of the structure. Hence, the inventive damping treatment provides a cost-effective way of controlling critical vibrations.
The present invention is especially advantageous insofar as controlling extremely large vibrations. The customary approach to control of very great vibrations involves application of a large amount of conventional damping treatment (which implements elastomeric material)—an approach necessitated by the relatively small loss factor associated with conventional damping treatment. In particular, this invention cost-effectively reduces excesively large flexural vibrations in beam-like, plate-like and cylindrical structures subjected to various loading conditions in a broad frequency range.
Depending on the application, inventive practice can succeed in any or all of the following: (i) reducing the radiated acoustic noise from one or more structures; (ii) reducing the structural-borne transmission path or paths; (iii) providing a comfortable and quiet environment for a ship or a building; (iv) reducing the requirements for vibration-sensitive equipment.


REFERENCES:
patent: 3110262 (1963-11-01), West
patent: 3130700 (1964-04-01), Peterson
patent: 4173130 (1979-11-01), Sutliff et al.
patent: 4350233 (1982-09-01), Buckley
patent: 4560150 (1985-12-01), Shtarkman
patent: 4706788 (1987-11-01), Inman et al.
patent: 5712447 (1998-01-01), Hanson
patent: 5855260 (1999-01-01), Rubin
patent: 5984233 (1999-11-01), Snyder, Jr. et al.

Affiliated with

Also associated with

Rating

Tuned broadband vibrational dissipator does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Tuned broadband vibrational dissipator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tuned broadband vibrational dissipator will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2613463