Talk:Stress (mechanics)

message: for one thing, it focuses exclusively on solid material - what about fluids and gasses? For another, the most important concepts are buried under mountains of crap - the most simple, basic and important concepts, like ductile materials failing under shear and brittle failing under normal, fluids supporting normal but flowing under shear ... that should be in the intro. Instead, the article drones on and on with graduate level tensor math that should be spit into other articles.  --32alpha4tango (talk) 20:59, 1 June 2011 (UTC)
replies: text: Great ideas. Please add them (with references)! Mgnbar (talk) 22:22, 1 June 2011 (UTC)
replies: text: This article is about the concept of stress, not about strength of materials. It is very tempting to start writing in this article about ductile materials, the mechanical behaviour of solids (metals, rock, soil) and fluids under different loads. But this is not what this article is or should be about. sanpaz (talk) 16:46, 10 September 2011 (UTC)

text: I agree wholeheartedly, but for different reasons. This article is focused way too much on engineering aspects, as opposed to the basic physics, and spends too much time trying to explain simple concepts in a confusing manner. Stronger emphasis needs to be placed on the general applicability of the stress tensor to continuous media, and on its physical meaning. The overall formatting is crap. Why is the basic equation \mathbf{T}^{(\mathbf n)}= \boldsymbol{\sigma}\cdot\mathbf n  in the middle of the article? Also, \mathbf{n} is not explicitly defined before being used. Furthermore, for an article about the stress tensor, how come there is no link to the Cauchy momentum equation? Also, why is there no mention of the connection to non-mechanical stress tensors like the Maxwell stress tensor? Why, in many of the equations, are the individual components of the tensor written out? Either vector notation, or Einstein notation (with links to the appropriate pages in the intro) should be sufficient. I personally have never written a wikipedia article before, but this one needs some serious revision.198.125.228.16 (talk) 18:21, 2 April 2012 (UTC)

text: T is the stress vector. Te1 is the stress vector associated with a plane with normal vector e1. Then, T1(e1) is the component (scalar) in the x1 direction of the T vector (associated with the plane with normal vector e1). sanpaz (talk) 17:06, 15 February 2013 (UTC)
thread_title:  This article sucks 

message: The "Introduction" section (now "Overview") has gone through a general revision. Hopefully not too many errors were added and the notation was not messed up too much. I plan to work a bit more on this article over the next couple of days.  --Jorge Stolfi (talk) 04:03, 7 February 2013 (UTC)
replies: text: As your revision included most of the text already in existence, it will take some time to see if some of the text removed is missing in the new revision. At first glance, I noticed you removed the figure that appeared in the introduction. This figure is very useful to show the concept of an infinitesimal element and the stress tensor associated with it. I will include the figure again. sanpaz (talk) 19:42, 7 February 2013 (UTC)
replies: text: That figure seemed too detailed for the needs of the head section.  Isn't the "double bubble" picture (below the protractor photo) sufficient for that section? --Jorge Stolfi (talk) 03:08, 8 February 2013 (UTC)
replies: text: Perhaps it is too detailed for the introduction. However, I think it is very useful in later section. I'll think about where to place it.sanpaz (talk) 16:19, 8 February 2013 (UTC)

text: Continuing with the general revision, I noticed that the section "stress (mechanics)#Stress analysis" was almost a verbatim copy of part of the stress analysis article.  Some duplication between articles is unavoidable and even good, but verbatim copy is annoying to readers and demands twice as much work from editors.  So I trimmed that section of this article, and moved to the stress analysis article some material from stress (mechanics)#Mathematical background that seemed to belong there.  I hope I did not do much damage in the process. --Jorge Stolfi (talk) 03:31, 10 February 2013 (UTC)
replies: text: Jorge, are you planning on moving a lot of the content of stress (mechanics) to other articles (stress analysis, Euler-Cauchy stress principle) and leave this article dealing with stress in a general sense? I think that would be a good idea.sanpaz (talk) 18:21, 11 February 2013 (UTC)
replies: text: I am tempted to do that, but I do not know whether I will have the energy. 8-) --Jorge Stolfi (talk) 01:25, 12 February 2013 (UTC)
thread_title:  General revision 

message: The main theoretical sections were way too long and dense.  They have been split off to Cauchy stress tensor and Euler-Cauchy stress principle, where they will be hopefully easier to read and edit.  Of course, summaries of those sections should remain here with wikilinks to those articles. I will try to do that in the coming days, but please help. --Jorge Stolfi (talk) 22:14, 23 February 2013 (UTC)
thread_title:  Theory sections have been split off 

message: The "Further reading" list seems way too long, and some of the entries seem rather specialized (e.g. specific to soil mechanics and geology).  Some entries have been already moved to the split-off articles Cauchy stress tensor and Euler-Cauchy stress principle, but the list still needs some  trimming IMHO.  Perhaps move some enrties to continuum mechanics? --Jorge Stolfi (talk) 22:19, 23 February 2013 (UTC)
thread_title:  "Further reading" section needs trimming 

message: Key ideas such as the Euler-Cauchy stress principle have been banished to other pages. The definition of the Cauchy stress tensor is gone.  The excellent figures demonstrating the balance of internal forces are gone. There is a new and rather confused section on stress analysis. There is a considerable amount of redundant material. There are absurd references to "particles" midway in the article, which defeats the whole purpose of introducing a continuum framework to define stresses, to begin with. And what purpose does that picture of a tank car serve? 
Dr. Stolfi, no doubt your edits were made with the intention of improving things but excuse me when I say that they have really hurt the article. The previous version was excellent, rigorous, comprehensive  and of high quality overall (thanks to the tireless efforts of editors Sanpaz and Bbanerje, who are both experts in continuum mechanics). Watching it over the years, it had also reached a degree of stability. Unfortunately, I have neither the time nor the energy to make the extensive edits this article needs. Commutator (talk) 05:34, 25 March 2013 (UTC)
replies: text: Please provide diffs. Or just revert back to the version you preferred. KatieBoundary (talk) 10:50, 25 March 2013 (UTC)
replies: text: I think it is clear that this article has changed in scope. It went from addressing stress from the continuum mechanics perspective, to a addressing stress in a more general sense. I do not think this is a bad approach. What has happened is that the old article got the Cauchy stress tensor portion  (continuum mechanics component) removed from it and sent to a separate article, leaving the current article with the a general explanation of stress. What perhaps needs to be done in this article to further improve it is to make sure it covers all aspects of stress and also highlights the links to the most relevant related articles (Cauchy stress tensor, Stress analysis, Mohr's circle, Cauchy's equations of motion, Euler's laws of motion etc.)sanpaz (talk) 01:54, 12 June 2013 (UTC)
thread_title:  This (previously excellent) article has REALLY deteriorated in quality, rigor, completeness, accuracy and organization 

message: Is there a convention for the sign of simple uniaxial stress σ, or did I miss it in my reading of the article?  Although I didn't see it stated anywhere, it looked to me from the direction of the force vectors that in the equation F/A = σ, tensile stress is positive  (σ > 0) while compressive stress is negative (σ < 0).  --ChetvornoTALK 20:38, 17 April 2013 (UTC)
thread_title:  Sign convention? 

message: I think that the picture of the car window is not helpful for the article and should be removed. The resons are:
1. At the beginning of the article, there is already a picture clearly showing the visual effect of stressed materials when viewed through a polarizing filter
2. The most dramatic changes between the two views of the car window are not caused by the stress internal to the material, but by the reflection properties of its surface. With this I refer mostly to the transparency of the window when viewed with the polarizing filter. The finer structure caused by the material intrinsic stress is only visible when the picture is view in screen size and is much fainter than the one described above.
Don't get me wrong, I think the picture is technically advanced , but I also think it illustrates the change of transparency much better than the effect of stress.
132.187.199.137 (talk) 11:25, 6 July 2015 (UTC)
replies: text:  The stress zones of the protractor are not intentional but inevitable result of the production process, while the stress matrix of the car window is an outcome of a purposeful design and very exact planning. It is of course my subjective and biased view and I humbly wonder whether other wikipedians approve the deletion of my photo. Etan J. Tal(talk) 12:07, 6 July 2015 (UTC)
thread_title:  Redundant Picture 

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thread_title:  External links modified 

message: Stress 106.196.15.64 (talk) 13:23, 28 August 2022 (UTC)
thread_title:  Stress