# Talk:Vibration

## Definition

Is this really the definition of vibration? I think that a vibration is a mechanical oscillation, characterised by the interaction between inertia and some restoring force. Thus pendulum, rigid body and elastic body all vibrate. Can anyone justify the current (unhelpful in my view) definition? Some vibrations propagate and are waves. Part of the reason for getting involved here is that I have just written Rossby wave and would like there to be a general reference somewhere to restoring force. We could then get all waves articles in uniform layout. Vibration would be a good place to put the general principle of restoring force but not with the current definition. Cutler 22:24, 7 Feb 2004 (UTC)

I totally agree.

The use of vibration in enhancing sports performance must surely be a sphere of very limited interest relative to the importance of vibration in mechanical engineering. Mr. Bosco - could you move the references to your fine work to a sub-section of vibration ?

I created a new page for that. Greglocock 22:28, 11 January 2007 (UTC)
which has now been deleted because the whole thing was a copyvio. No good deed goes unpunished. Greglocock 23:41, 28 January 2007 (UTC)

I'd suggest correcting the definition to "vibration refers to RAPID mechanical oscillations about an equilibrium point", for the same reason we don't say that a clock pendulum or a rocking ship "vibrate". — Preceding unsigned comment added by 90.173.47.145 (talk) 16:00, 20 November 2011 (UTC)

Lzyvtl why do you keep removing them, they are a classic example that most people have experienced, unlike earthquakes? Greglocock 22:28, 11 January 2007 (UTC)

## Damping

Shouldn't other damping models be adressed? Structural damping (linear hysteretic) is so common that a section might be included to explain it. And maybe a short reference to Coulomb's and viscoelastic models wouldn't be bad... —Preceding unsigned comment added by 193.136.128.14 (talk) 18:04, 6 September 2007 (UTC)

## Religious meaning

This is a perfect article on vibration as a physical concept. But in English, the word is also used with metaphysical meanings, and the article is somewhat incomplete with an explanation of that - or at least a disambiguation page. Natha 67.52.81.242 (talk) 19:33, 14 December 2007 (UTC)

What do you mean by a metaphysical meaning? I can't think of another meaning for vibration other than physical oscillation of some sort, and I speak English natively. In any case, if Wikipedia did have a page for it, it would be a separate page, and it would give it the same treatment as it does phrenology and other pseudosciences. Sobeita (talk) 21:17, 6 November 2010 (UTC)

Perhaps we could have a disambiguation page pointing at pseudoscience for those spiritual vibration freaks? 81.151.13.18 (talk) 18:40, 21 December 2007 (UTC)

## Speed

Is there any specific paragraph on anything related to "speed" of vibration. New Babylon 2 (talk) 03:13, 1 March 2008 (UTC)

sound is when cat's eat corndogs —Preceding unsigned comment added by 24.253.129.79 (talk) 19:30, 24 April 2008 (UTC)

## New image

I was thinking that Image:Simple harmonic oscillator.gif would be great for somewhere in the article about non-damping vibration? I'm no expert on this, so I figured that someone would know where to put this. Thanks!

--pbroks13talk? 02:27, 24 May 2008 (UTC)

Thanks for the suggestion. I put the gif in the undamped section.

Lzyvzl (talk) 03:46, 10 June 2008 (UTC)

## Multiple degrees of freedom systems and mode shapes

Can someone re-work the equation on that page "describing" the OEM with the 2 masses, 3 dampeners and 3 springs? Why is there an x3? There should not be an x3 unless x3 is some kind of combination of x1 and x2. Can anyone clear this up? —Preceding unsigned comment added by 12.152.193.133 (talk) 14:47, 24 October 2008 (UTC)

I think it is fine as it is. x3 = 0 in the example given, and the 'wise' editor eliminated it from the matrix form of the system equation. Greg Locock (talk) 04:06, 25 October 2008 (UTC)

The note: "Note: Using the exponential solution of is a mathematical trick used to solve linear differential equations. If we use Euler's formula and take only the real part of the solution it is the same cosine solution for the 1 DOF system. The exponential solution is only used because it easier to manipulate mathematically" is at the least very misleading. Using the exponential solution is no "trick", the exponential is used because complex exponentials are the basis for solutions of linear differential equations. The part on using Euler's formula is also extremely imprecise. The last sentence of the note is also very informal and as said, it is not used only for manipulation convenience. Maybe all the note could be replaced by a link to Ordinary Linear Differential Equations. — Preceding unsigned comment added by 131.180.156.248 (talk) 15:19, 18 April 2013 (UTC)

## who is we?

the article talks about "we" a lot, i think that looks odd in an encyclopedia, sounds more like someone borrowing an explanation from a text book. Mikachu42 (talk) 00:57, 1 December 2008 (UTC)

Agreed, but it is just a style thing. You could try and recast it into an impersonal passive voice, something 'we' were discouraged from at university, even for formal reports. MOS recommends against we/you but not for the reason you give, and to my mind this article does not fall afoul of that stricture. Greglocock (talk) 01:37, 1 December 2008 (UTC)

This page does not sound like wikipedia. Numerous points, "To start" "What is resonance?" —Preceding unsigned comment added by 69.136.72.16 (talk) 22:59, 1 February 2010 (UTC)

## Missing reference

I think the following statement should be removed from this article until a reference can be provided:

Generally, one or more "input" or "control" points on the DUT are kept at a specified vibration level.

In that article Mr. Tustin states "Most lab personnel mount the control accelerometer at some location on the DUT side of the fixture." This contradicts what the Wikipedia article is saying.

12.188.106.66 (talk) 15:39, 24 February 2010 (UTC)

I see that the external link to the MacAnalyis training manual has been restored with the justification that it is "becoming popular". WP:EL does not list popularity of a site as a valid reason for inclusion. It also fails the test for inclusion in that sites that do not "provide a unique resource beyond what the article would contain if it became a featured article" should be avoided. In my view the link is there to advertise MacAnalysis's training and not to add value to the Wikipedia article. The complete manual is not available, it is only a limited "see inside" for a few pages, all of which are made difficult to read by the use of a prominent, intrusive watermark. SpinningSpark 06:42, 9 April 2010 (UTC)

Agree 100%.Greglocock (talk) 23:38, 9 April 2010 (UTC)

## First Image inconsistent with text

I just noticed that the blue image of the mass on top of the spring seems inconsistent with the text. On the image the positive direction of motion (x) is upwards, but in the text the spring force is F=-kx, which implies that the spring force is downwards, which doesn't make sense if the spring is pushing the mass upwards. Similarly, the force due to gravity is defined in the text as F=ma, implying that the gravitational force is in the positive x direction. This is inconsistent with having the x-axis upwards on the diagram. I think the diagram needs to be amended or removed... unless I am confused :-) Ibrace (talk) 15:30, 10 October 2010 (UTC)

Here are a couple comments about the sign convention...it can be confusing.

If the mass is moved up in the positive direction the spring stretches. The spring force then is pulling down on the mass to bring it back to the unstretched state. Hence, the spring force is pulling down in the x direction (i.e. the "-x" direction).

The "a" in F=ma is not the acceleration due to gravity. It is simply the acceleration of the mass. If "a" is positive upward then there is a positive force acting up (e.g the spring has been compressed and wants to push up on the mass). It is not stated, but the assumption is that the mass has compressed the spring due to gravity "g" (or there is no gravity). You can show that "g" can be neglected in the analysis since "g" is constant, but I avoided this because it would complicate the explanation. —Preceding unsigned comment added by Lzyvzl (talkcontribs) 03:45, 20 November 2010 (UTC)

## vibration testing

Sine (one-frequency-at-a-time) tests are performed to survey the structural response of the device under test (DUT) --> This is not completely right. There are a lot of sinusoidal vibration tests the are related to reality. For example vibrations from a engine or a motor. 198.175.151.212 (talk) 05:55, 15 October 2010 (UTC)

## Desirable and undesirable sounds

The parts on desirable and undesirable sounds ("More often, vibration is undesirable") is too objective. — Preceding unsigned comment added by 137.150.199.70 (talkcontribs) 19:02, 18 February 2011

Don't you mean too subjective? SpinningSpark 20:33, 18 February 2011 (UTC)

## Vibratory analgesia

The article is perfect and so I do not think it is possible to mention the analgesic properties of vibrations from some 5Hz to 200Hz - optimumm observed somewhere between 50Hz to 100Hz. The energy to stimulate large diameter neuron transmitting signal from tactile and tension receptors in the skin and muscles ranges between 50 mW to 5W, typically. A simple diagram showing Melzack[1]

gating theory of pain at work in the vibratory analgesia.
--Capekm (talk) 03:05, 15 April 2012 (UTC)

## Destructive vibration ignored

A significant weakness of this article is the lack of any mention of the potentially destructive structual effects of vibration, which is the major reason for engineering analysis and testing. ("Occasionally desireable", and undesireable because of wasted energy and noise, seriously?) JustinTime55 (talk) 21:19, 28 January 2015 (UTC)

## Wrong Equation ?

the formula given as definition of the critical damping :

${\displaystyle c_{c}=2{\sqrt {k \over m}}.}$

is in contradiction with the one given in the article about damping ratio. It is also incoherent with the equation coming immediately after. RenoSarastern (talk) 08:11, 17 March 2016 (UTC)

## REFERENCES for talk on vibration

1. ^ Melzack R, Wall PD. Pain mechanisms: a new theory. Science 1965; 150:971–979