# Machine design problem

I am getting confused with the maths in the max distortion strain energy part of the question. Plus there is a misprint as the formula for distortion should be a^2 +b^2-2ab=(yield stress)^2, here they have missed the 2 in 2ab. Or maybe I am wrong

Can someone please solve it correctly showing the working(maths). I just need a step by step working as I am making some error solving it myself. And the one solved here is missing steps. *F.S=1 that's why not mentioned.

Thanks

• Welcome to Engineering! This looks like a homework question. In order for such questions to be answered in this site, we need you to add details describing the precise problem you're having. What have you tried to solve this yourself? Please edit your question to include this information.
– Wasabi
Commented Nov 26, 2017 at 20:20
• Can't be bothered to put my laptop on its side... Commented Nov 26, 2017 at 20:36
• Actually it's not homework. Preparing for exams. The reason I didn't mention the question is because I am only having problem in this part of the question. And the problem is the maths. Everything needed to solve is already there in the picture. Values of major and minor principal stresses are shown there in the picture.
Commented Nov 26, 2017 at 20:40
• @solar Mike there the picture is upright now.
Commented Nov 26, 2017 at 20:43
• The answer has already been given why would I come here if it was just for homework. I posted it here because I couldn't understand the solution (working) the writer has shown. It is missing crucial steps that's what I want help with
Commented Nov 26, 2017 at 20:50

Maximum distortion strain energy formula from your example is reduced von Mises formula, so the calculation should be correct. It does not comply the binomial theorem because of specific physical properties of material and stress tensor components relations.

It's very easy ask google question. Though always check wikipedia's answer and try finding some lecture notes or other literature if possible peer reviewed.

• Thanks for the answer. So is reduced von mises formula used in case of only ductile materials? What specific physical property are there.
Commented Nov 26, 2017 at 22:09
• You should go through theory part again to understand formula. Commented Nov 26, 2017 at 22:32
• @Adi Poison factor differes depending on material but von Mises stres can be used in general but in special cases when some tensor components are 0 you get reduced formula, depending is it plain stress, simple shear or uniaxial stress Commented Nov 26, 2017 at 22:39
• Well there is not much theory in the book i have, just a definition and the formula(non reduced one). This reduced formula was used in an example which confused me. I will look somewhere else now that I know what to look for. Thanks for the answer.