Is the Maximum Shear Strain Direction Always 45 Degrees?

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Discussion Overview

The discussion revolves around the determination of the angle associated with maximum shear strain in the context of solid mechanics. Participants explore whether the angle is always 45 degrees relative to the principal plane and how to approach the problem without using Mohr's circle.

Discussion Character

  • Homework-related, Technical explanation, Debate/contested

Main Points Raised

  • One participant calculated the maximum shear strain but is uncertain about how to find the angle, questioning if it is simply the angle between the maximum shear plane and the principal plane, which is stated to be 45 degrees.
  • Another participant suggests familiarity with Mohr's circle but notes that their professor advised against using it for this specific question.
  • A participant expresses difficulty finding a method to determine the direction angle of maximum shear strain using only principal strains and maximum shear strain.
  • Some participants propose that the question is indeed asking for the angle between the maximum shear plane and the principal planes, which they believe is always 45 degrees.
  • Several participants affirm the idea that the angle is always 45 degrees, indicating agreement on this point.

Areas of Agreement / Disagreement

While there is some agreement among participants that the angle is always 45 degrees, there remains uncertainty regarding the method to derive this angle and whether the question's intent is fully understood.

Contextual Notes

Participants mention limitations in their textbooks regarding the derivation of the angle, and there is a noted restriction on using Mohr's circle for this problem.

temaire
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Homework Statement



14714206e9ccb8064cc7579fbf9cfc640441a831.png


Homework Equations



\gamma_{max} = {\left|{\epsilon_1} - {\epsilon_2} \right|}

The Attempt at a Solution



I calculated the maximum shear strain to be 200 \mu.

For the angle, I don't know exactly how to go about finding it. However, the solution says that the angle is 45^{\circ}. Does this mean that all they were asking was to state the angle between the maximum shear plane and the principal plane, which is always 45^{\circ}? Or am I supposed to solve for the maximum shear plane angle by first finding the principal plane angle and subtracting 45^{\circ} from it?
 
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You need to get chummy with your buddy the Mohr stress/strain circle... although just looking at the question you could solve it purely from math. I assume you have a solid mechanics or mechanics of materials textbook you could easily find it in there.
 
CJSGrailKnigh said:
You need to get chummy with your buddy the Mohr stress/strain circle... although just looking at the question you could solve it purely from math. I assume you have a solid mechanics or mechanics of materials textbook you could easily find it in there.

Our professor explicitly told us not to use Mohr's circle for this question.

I have tried looking through my mechanics of materials textbook, but couldn't find a way of solving for the direction angle of the maximum shear strain, just with having the principal strains and the maximum shear strain.

I want to know whether the question was supposed to ask you to state the angle between the maximum shear strain and the angle and the principal plane angle. I know this sounds trivial, but the answer to this problem does say 45^{\circ}.
 
temaire: I currently think you worked the problem correctly. I currently think all they were asking for was to state the angle between the maximum shear plane and principal planes, which is always 45 deg.
 
nvn said:
temaire: I currently think you worked the problem correctly. I currently think all they were asking for was to state the angle between the maximum shear plane and principal planes, which is always 45 deg.

Thank you nvn. That's what I was thinking as well.
 
Always 45 deg. You're right.
 

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