Talk:Strain gauge

Comment
Doesn’t sorcery in reference 23 belong on another webpage? The listing of Zemic and Hottinger Baldwin Messtechnik look like advertisements. Comment by Ray Delcher — Preceding unsigned comment added by 216.24.45.40 (talk) 21:37, 23 March 2023 (UTC)

anyone can give me more information about strain gauges? notify me at jib_zbz@yahoo.com

Murphy's Law
I understand that the error made by the engineers in the Murphy's Law story was that the strain gauges were wired up incorrectly in the Wheatstone bridge NOT that they were installed at 90 degrees. I quote the story at the linked page:

http://www.improbable.com/airchives/paperair/volume9/v9i5/murphy/murphy1.html

So I have altered this note slightly.--Turtle (talk) 21:59, 1 April 2008 (UTC)


 * If valid then why does it not have anything at the website quoted, it is neither on the page nor found with the search engine.
 * Also Murphy's law has no mention of it. Aether22 (talk) 23:04, 2 June 2008 (UTC)


 * Hi Aether22, sadly the website above has changed since I read the article. It seems the excellent Murphy's law story the website ran has been taken off and is now sold as a book? Since this the link is now no good to the article I'll change the citation. --Turtle (talk) 21:21, 16 June 2008 (UTC)

In my opinion, this anecdote doesn't belong here anyway, but rather in the Wheatstone bridge article. It is an unnecessary distraction. 188.103.189.134 (talk) 16:41, 24 April 2018 (UTC)

Spelling
I'm not greatly fussed about "gage" and "gauge". But, if the article is "Strain gauge" and "Strain gage" redirects, then the spelling should be "gauge". If the article was "Strain gage" and "Strain gauge" redirected, then we should use "gage". Changed. Mr Stephen 22:20, 10 April 2006 (UTC)

Industry standard has been "gage". Omega and Micro-Measurements use gage throughout their sites. Most of the citations on this wiki page use gage. HBM seems mostly to have switched to gauge, despite the fact that their incredibly thorough book "An Introduction to Measurements using Strain Gages" uses gage. It is now available as a free .pdf from the HBM website under the title "An Introduction to Stress Analysis and Transducer Design using Strain Gauges", but the only change from gage to gauge is in the title. 12.230.47.87 (talk) 23:01, 11 July 2017 (UTC)
 * "Industry standard" according to whom? I worked in the industry and I never used the American spelling. Some companies use "gage" (e.g., MicroMeasurements, Omega) while others use "guage" (e.g., Kyowa, BCM) The article has used "gauge" since it was written. And I don't see any need to have an "also" known as for a minor spelling variation. Meters (talk) 01:41, 12 July 2017 (UTC)

Piezoresistive effect
The common metallic foil gauges do not use the piezoresistive effect, but rely on the geometric change, ie $$r=\frac{\rho l}{A}$$. Deleted. Mr Stephen 22:20, 10 April 2006 (UTC)
 * On re-reading, I realise that this may mislead. I don't dispute that $$\rho$$ changes with strain. Mr Stephen 21:18, 12 April 2006 (UTC)

Temperature effects
It is quite hard to create strain-free dummy gauges that are at the same temperature as the specimen. The usual technique is to use gauges made of Constantan or another alloy with a small thermal coefficient of resistance and a three-wire connection. Mr Stephen 22:20, 10 April 2006 (UTC)


 * Done -- added to article. --75.41.34.231 17:41, 21 May 2007 (UTC)

Strain Gauge History
Although Edward E Simmons developed a woven gauge, it was Arthur Claude Ruge at MIT who, at the same time in 1938, developed the first practical gauge where resistance wire was glued to a backing material. (An introduction to Measurements using Strain Gauges HBM) Patrick1950 15:41, 4 December 2006 (UTC)
 * All references I could find credit Edward Simmons with the original invention of the strain gauge (though many credit him for inventing it in 1936, rather than 1938). If the Ruge strain gauge is such a notable type of strain gauge, I don't see why it shouldn't also be added to the article. --Karnesky 17:24, 4 December 2006 (UTC)

The size of a strain gauge
I think the typical dimensions of a strain gauge should be clearly listed in order to improve this article.


 * Define "typical". When I worked in a testing lab, I dealt with gauges ranging in size from 2mm x 1mm to 25mm x 10mm. --Carnildo 22:57, 10 February 2007 (UTC)


 * Well there you go! :-) Robert K S (talk) 16:36, 17 June 2008 (UTC)


 * I have used bondable foil strain gauges with a grid as short as 0.015 inches and as long as 4 inches. MicroMeasurements makes strain gauges as short as 0.008 inches and Omega makes a 6 inch long strain gauge. The "typical" length depends entirely on the application. Measurements on concrete and other heterogeneous materials require a very long gauge length, but measurements of strains at local stress concentrations require a very short gauge length. I'll add something to the article. Meters (talk) 22:01, 20 October 2011 (UTC)

Introduction
It is not a good idea to have formulas in the introduction.--Kölscher Pitter (talk) 09:43, 10 January 2008 (UTC)

Physical operation
There are factual errors in the explanation.
 * A typical strain gauge arranges a long, thin conductive strip in a zig-zag pattern of parallel lines such that a small amount of stress in the direction of the orientation of the parallel lines results in a multiplicatively larger strain over the effective length of the conductor—and hence a multiplicatively larger change in resistance—than would be observed with a single straight-line conductive wire.

The strain does not increase: strains are dimensionless and are usually expressed as a decimal fraction, a percentage or in parts-per notation. If the strain is 1%, every segment is stretched 1%, and the total sum of the segments also increases with 1%. Ssscienccce (talk) 22:35, 13 September 2012 (UTC)
 * Good point. The filament zig zags because, like almost everything in strain gauge design, its length is a compromise. Gauge resistance is standardized (usually to 120 or 350 ohms) so a filament of a particular cross section needs to be a particular length. That length is generally much longer than the desired gauge (measurement) length and thus the filament is folded or zig-zagged. Unfortunately this increases the gauge's sensitivity to transvers strains. Why not make the cross section small enough that the resistance/length is high enough that the filament does not need to be folded? Because the area of contact between the filament and the substrate would be too small to prevent the gauge from heating up. Reducing the voltage to reduce the power (and heating) would lower the sensitivity of the measurement system... and on and on. I've been meaning to do a major review of this article. Maybe this will remind me. Meters (talk) 23:34, 13 September 2012 (UTC)
 * Well, I'm no expert on strain gauge tech, but this edit, I believe fixes this matter of syntax and terminological inexactitudeness. Regards // Fra nkB 16:28, 3 June 2013 (UTC)

Misleading lede?
By concentrating on electronic strain gauges, the lede of the article suggests that strain guages were invented in the 1930s - in fact other types of (presumably mechanical) strain guages were in use earlier - Warrior to Dreadnought: Warship Development 1860–1905 by D K Brown (1997) refers to a series of strength trials carried out on the destroyer HMS Wolf in 1903 which involved the fitting of some 30 pairs of strain gauges (p. 184–185.).Nigel Ish (talk) 22:11, 6 December 2013 (UTC)

Mechanical types
While there are mechanical means of measuring strain, the example used in this section is not actually measuring strain. It is measuring displacement across a crack, not strain. I suggest removing this example. Meters (talk) 16:05, 11 April 2016 (UTC)
 * removed. Meters (talk) 17:22, 29 April 2016 (UTC)

Definition of 'force collector'
This phrase is used a number of times in the article. It feels like a technical term in strain gaugery, so I think that it ought to be defined before it is used. I know little about the subject, so leave it to someone else. Macboff (talk) 15:20, 28 March 2022 (UTC)