Talk:Ultimate tensile strength

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Both tables in the article list "Ultimate strength" for the same materials but they are very different, so at least one table must be in error. Can someone please correct this!

There is a problem with the annealed Cu and Al yield stresses. First: 15-20 MPa is too little for Al yield strength even when annealed IMHO. http://www.roymech.co.uk/Useful_Tables/Matter/Copper_Alloys.html also states a zero-two stress of down to 50MPa for Cu whereas the wikipedia article says 33MPa for annealed 99.9 Cu.

The last paragraph of the article:

... Tensile strength can be measured for liquids as well as solids. For example, when a tree draws water from its roots to its upper leaves by transpiration, [...] ten metres, and trees can grow much higher than that. (See also cavitation, which can be thought of as the consequence of water being "pulled too hard".) ...

I think that the above except is about suction and so, not tension and neither tensile strength and doesn't belong to this article. Suction of liquids better relate to tensile stress, not strength (= the limit state). Stefanos 11:19, 9 Jan 2004 (UTC)

actually, WTF am I saying. I think it's that that 10 metres (~33') should be 70', but check it. Sorry --Kwantus 20:25, 20 Sep 2003 (UTC)

Argh. I think the article's got me confusing the tensile strength of the water with its use as a barometer...that's what i gotta rewrite. how to explain and separate the two --k

I may also have gotten the depth from which a well pump can draw with a little air in the pipe (can i call that primable depth?) vs the depth with solid water. --k

Aha. Cavitation is a much better approach than trees, 'cause it avoids all the difficulty about do trees haev microvalves and pumps, osmotic pressures, capillarity, atmosphere ... me happy now =) -- Kwantus 15:41, 21 Sep 2003 (UTC)

LOL near-total irrelevancy I can't help but save from the sci.physics thread:

>You will find that the sap is under negative pressure.

Balls. How the hell do you think folks in Canada collect maple syrup?

I do love such earthy yet practical rebuttals =) -- Kwantus 15:32, 21 Sep 2003 (UTC)

Possibly being picky here, but isn't the SI Unit usually used for tensile strength N/mm^2 (MPa) and not N/m^2 (Pa)?

The word "unit" is used with various meanings. In metrology publications such as the NIST guide, it sometimes includes megapascals and newtons per square millimeter, but at other times the word unit is limited to the base units and their combinations, and MPa and the like are referred to as multiples and submultiples of SI units. Basically, what I'm pointing out is this: there is no reason to interpret "units" being specified in newtons per square meter or in pascals as excluding combinations of those units with whatever prefix is appropriate for the context.

If someone can come up with a simple way to make that point clearer, okay. However, I don't see any real need for such a clarification in hte article. Gene Nygaard 19:25, 11 August 2005 (UTC)[reply]

Isn't the UTS just the peak of the graph? It is not nessisarily the fracture point, but just the point at which no extra stress is nessisary to deform the object. After this point if the load is not released, it will continue deform until it ultimatly fractures. This is also the point at which necking beings...

Space elevator

Hi. I noticed that the Space elevator article describes "tensile strength" as being "the limit to which a material can be stretched without irreversibly deforming" but the Tensile strength article states that:

"The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before it breaks."

Upon further reading of the tensile strength article, it looks like tensile strength is divided into "yield" and "ultimate" (the former being the limit of tensile stress which material can endure and retain its elasticity, and the latter being the limit of tensile stress before the material breaks).

Does anybody think that the elevator article should be updated to clarify this issue, and what is the best way to do so? Cheers TigerShark 10:26, 12 November 2005 (UTC)[reply]

I think the Space elevator article should be changed to specifically state yield or ultimate. I also believe that that discussion on which to use should take place inTalk:Space elevator. War (talk) 07:03, 18 February 2008 (UTC)[reply]

Possible inaccuracies

The last three entries of the first table - the one with the ceramic materials boron, SiC, and Al2O3 all have values listed under the yield strength. Shouldn't they be under ultimate strength, since the elongation of ceramic fibers are taken to be negligible in the tensile testing process?

Proposed merger

There are several reasons for the merger:

The concepts of yield strength and UTS are already presented in the Strength of materials article. If necessary the other article can be expanded to cover additional points (it needs work anyway)
Tensile strength is a loose term that normally means UTS but is used interchangably by many people. This point can be clarified in the strength of materials article if necessary
The concepts section is a copy of the Stress-strain curve article. This can be replaced with a link.
There are multiple errors (such as cast iron having a negligible tensile strength). These do not seem worth correcting
The only information not covered elsewhere are the tables of properties. These could be put into their own article and expanded to cover other mechanical properties. This could then be referenced from the yield, strength, stress, plasticity, etc articles.

Comments welcome Slinky Puppet 18:17, 11 January 2006 (UTC)[reply]

Agree. I'd like to see a lot of refactoring in the materials science/engineering related articles, maybe there should be a project. The table of properties seems pretty useless to me - a few entries for common materials is nice to give folks a sense of scale, but I don't see why it should be so inclusive.

The redundancy between the concepts section and the stress-strain curve article is mostly my fault. I couldn't think of a way to distinguish between yeild strength, UTS and breaking strength without it. I wouldn't be sad if someone else found a way to do that without the redundancy. Toiyabe 19:06, 11 January 2006 (UTC)[reply]

I agree that the materials science/engineering stuff could really do with a brush up. The hardest part is trying to find where everything fits in. Possibly we could make the 'strength of materials' article a kind of overview with brief introductions and, where relevent, a link to a more detailed article. I've seen this kind of layout on a few really nice aricles and it seems to work well. I think I will try to make a mindmap of articles on my talk page. When it's up I'll leave a link here.Slinky Puppet 12:45, 20 January 2006 (UTC)[reply]

Merging them is not a good idea. You will end up with lots of links to too general a topic to be useful to anybody. Gene Nygaard 03:41, 12 January 2006 (UTC)[reply]

I don't understand. If I merge I will reduce the number of links. The current tensile strength article is really a stub (once the repeated stuff is taken out) and there is little to be gained by linking to it. I suspect it would be better replaced by an article on what happens at failure. Slinky Puppet 12:45, 20 January 2006 (UTC)[reply]

You don't solve the problem of "tensile strength" being too ambiguous by linking the articles which use it to an even more ambiguous and general article.

If a link article is too general, people aren't going to bother to wade through it. The linking is then useless. They often want to be able to identify one specific concept, not learn a whole branch of science. Gene Nygaard 14:04, 20 January 2006 (UTC)[reply]

'tensile strength' is not ambiguous. It is the maximum stress to which a material can be subjected. That is all it is. Everything else on this page is fluff to beef a stub into a proper article size (and 99% of the fluff is found elsewhere). It would be good to put all the things that keep getting repeated in other articles and in such a way that people can see how everything fits together before diving into the details. People can't look up a topic if they don't know it exists. There is currently an empty mechanical properties article that could probably be a useful starting place. Slinky Puppet 18:42, 6 February 2006 (UTC)[reply]

You say that tensile strength "is the maximum stress to which a material can be subjected." Sounds nice, but it means nothing. Subjected to before failure? What is failure? Toiyabe 19:55, 6 February 2006 (UTC)[reply]

I agree that this should be merged with Strength of Materials. "Tensile strength", if it had its own page, is really nothing more than a definition. Perhaps it needs a Wiktionary page, but not a Wikpedia page. - EndingPop 02:46, 22 February 2006 (UTC)[reply]

I don't think that the articles should be merged. Tensile strength is obviously a subset of the general strength of a material. However, the very first paragraph of the latter article contains a number of links such concepts, including tensile strength. Together, they seem a wide enough array of concepts to warrant their own pages. Certainly someone concerned with what the "tensile strength" of some material they were looking at means may not need to worry about its compressive or shear strength, if they were just interested in the term. Perhaps the article could be slimmed down with a few well placed links (or those even more refined subjects merged into it) but as a concept, it seems reasonable to have its own article. Almost any link leading to this article (and the vast number are from specific material pages) would be intersted in this specific property, and so the links would have to be directed to that subsection of the general strength article anyway to maintain their specificity, which would essentially render the merge useless. And that's from an otherwise dedicated mergist. 04:03, 11 September 2006 (UTC)

Unneeded Materials

The list of tensile strength contains several materials with no listed strengths. Why?

St Gobain "R" glass

St Gobain "R" glass has a tensile strength of 4400 MPa listed in the table. I have searched St Gobain's website long and hard and have failed to find such a high strength glass anywhere. Is this is a typo by any chance?

-Also, this value is listed under "yield strength." Most glasses I know break instead of yielding, thus I suspect it should be listed under "tensile strength."

References

Normally, I would get headaches citing things.

But the long list is subject to HUGE inaccuracies. For example, I had to correct the values for A36 steel in standard normalized condition. Those "in the know" would scroll across this page and laugh when they see A36 yielding at 400MPa (that's more like HSLA). A rather large embarassment I would suppose.

To remedy this, we'll need to start citing sources. I suggest looking up values on MatWeb. I have ASM handbooks in my university library and other resources so if anyone is in doubt I can look those up. When I have time.

Clear distinct yield point

Non-fictional materials do not have a clear distinct yield point. The sharp tip of point #2 in the "typical structural steel" stress-strain curve is grossly exagerated. There is never such a sharp peak stress. Furthermore, I just checked a bunch of stress-strain curves and accepted yield points in the MMPDS, and even for steels that follow this general curve shape the accepted yieldpoint is in the middle of the "bathtub" following the first stress peak. The 0.2% permanent strain threshold is the widely accepted yield point. References:[1] [2]--Yannick 03:15, 11 October 2006 (UTC)[reply]

This Is "Wrong"

Water is not, contrary to common knowledge, sucked up a tree held together by the tensile strength of the water! The vapor pressure of water, at the temperatures tree water is normally at, limit the height of that action to about 32 feet. Rather the water is pumped up the tree by the roots actively intaking water osmotically, and the fibers within the xylem transporting it to the leaves. The surface tension of the water on the cellulosic xylem fibers is the main effect here leading to a capillary wicking of the water up the tree. I see little in common with tensile strength.

The second paragraph of the Concept section reads, "Steel has a very linear stress-strain relationship up to its yield point, as shown in the figure. The yield point is not a sharply defined point, though; the figure is wrong. "

Figures are not "wrong," and are not even capable of being "wrong." They may be in "error," and the people who make them and interpret them are either "wrong" or "right."

What can I say, "It's all about the details."

Request

Would somebody please sort these tables by, say, increasing strength of the material (or even alphabetically)? I hate to ask, since I'm too lazy to do it myself... Sys Hax 15:12, 1 January 2007 (UTC)[reply]

How would you calculate tensile strength? (other then referencing to the chart)--Gunnar Berlin 17:23, 9 March 2007 (UTC)[reply]

Table correction

Silicon is not strictly metallic; thus I have deleted the word "metallic"

Tensile strength of rope

The article quotes:

"In general, the tensile strength of a rope is always less than the tensile strength of its individual fibers."

Is this correct? Thanks.

silicon

I found it odd that it has (by far) the highest tensile strength listed. Is that number accurate? 76.110.227.215 02:25, 27 August 2007 (UTC)[reply]

Engineering vs. true strain

The treatment in this article seems to reflect strictly "engineering" stresses and strains. These result from an assumption that the material dimensions don't change significantly during the test. Thus, when a measured load is divided by an area to get the stress, the divisor is the original area of the specimen, not the area it actually has (and as the tension is increased, that area is reduced.) Similarly, when the extension is divided by a length to get the strain, the divisor is the original gage length of the specimen, not the new length (and as the tension is increased, that length increases). The term generally used for the quantities that take these factors into account are the "true" stress and strain, and these are more appropriate for understanding what's going on in the material. Engineering stress and strain are entirely appropriate for design, though, because they are based on the components as designed, not as deformed. The article at [3]covers this nicely, and I suggest it be added to the external links. I think the article itself should mention that both views exist and that it's written to the "engineering" view. Mweir2 14:54, 30 October 2007 (UTC) I just observed this topic is broached under "stress (physics), redirectired from engineering stress." A link to that might be helpful, but the key-to-steel article really gives some good graphical explanation also. Mweir2 21:28, 5 November 2007 (UTC)[reply]

This Is "Wrong" II

For all "spanish" who want to change to the spanish translation: the link is wrong. Wikipedia shows the translation of the "yield strength" and not of the "tensile strength"!! I don´t know how to inform Wikipedia...(no time). fdo Frank T./Bilbo —Preceding unsigned comment added by 194.224.114.20 (talk) 09:15, 18 January 2008 (UTC)[reply]

Right, es interwiki link fixed. -Fnlayson (talk) 14:29, 18 January 2008 (UTC)[reply]

Ultimate Failure

I am editing the stub for ultimate failure and I was looking for a place to create a link through this article without stepping on any toes. I have noticed a few areas it could be included through the graphs at the very right or within the text. Please send a response either below this message or on the talk page of ultimate failure, thank you. Engl315ISU (talk) 19:57, 5 March 2008 (UTC)[reply]

Just add the link at the first best place you can find or add to See also. -Fnlayson (talk) 20:05, 5 March 2008 (UTC)[reply]

Necking

A couple of images showing necking have just turned up on Wikicommons. Image:Al tensile test.jpg and Image:Ductility.svg. I don't normally edit engineering articles so I will leave them here for anyone one who thinks they can be of use.--Aspro (talk) 17:53, 20 May 2008 (UTC)[reply]

Rewrite?

I'm thinking I might impose myself here and do a major rewrite. Here are the issues I see:

1. The article should stick to the single topic of tensile strength, and not broader topic of all measures of strength in tension. These could be noted at the end in an "Also See" section with links to other wiki articles.

2. A separate article on yield strength could/should be written. I'd be surprised if there wasn't already one here. I haven't checked yet.

3. The concept section covers the stress-strain curve in general. This should be a separate article. Let's focus on the conditions that produce a tensile strength.

4. I see a need for articles on tensile testing, compression testing, and others.

M610 (talk) 18:29, 19 November 2008 (UTC)[reply]