Wikipedia:Reference desk/Archives/Science/2017 November 26

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November 26

Mechanical Torsion

How do I calculate the total mechanical torsion experienced by a solid of revolution? I need to formulate the expression in terms of the total shear stress (s). I know that for a simple cylinder, it is the sum of the circumferential torsion and the angular torsion of both ends, but I don't know how the formula for the angular torsion was derived. Hence I can't derive a formula for an arbitrary rotating solid. I think that the assumption was made that the shear stress is evenly distributed over the ends, but is this a valid assumption?

How do I model the errosion process of the ends of a rotating prism with a particular cross-section? Obviously, the outer-edges will errose faster than the centre, but how much faster? I need to figure out an expression for how the height changes with time, radius, and angle. Plasmic Physics (talk) 11:07, 26 November 2017 (UTC)

I have a rotating cruciform prism, that is erroding from one end only. Over time, the side-profile changes from rectangular to bullet shaped. — Preceding unsigned comment added by Plasmic Physics (talk • contribs) 11:10, 26 November 2017 (UTC)

I considered adding this to the Math Ref Desk, but all the mathematical nouce in the world won't do you any good, if you're not familiar with the theory. Plasmic Physics (talk) 20:30, 26 November 2017 (UTC)

Our article is here: Torsion (mechanics). Graeme Bartlett (talk) 07:03, 27 November 2017 (UTC)

Thanks, but that article doesn't address my question. Plasmic Physics (talk) 07:30, 29 November 2017 (UTC)

At any cross section T=sum of shear stress*dA*r and shear stress is proportional to r. The rest is just maths. This assumes plane sections remain plane etc etc. Your second sentence in the question is curiously phrased. Greglocock (talk) 22:02, 3 December 2017 (UTC)

Electrical distribution planning and design

Hi, is there any body who knows how can I reach electrical distribution planning and design guidance/instruction/criteria for European countries? I searched on the net but I couldn't find any helpful material except a SIEMENS report. I do appreciate any help.--Freshman404^Talk 16:11, 26 November 2017 (UTC)

My Dad's book might be of use? --Phil Holmes (talk) 16:44, 26 November 2017 (UTC)

Published in 1905? -- ToE 18:45, 26 November 2017 (UTC)

A frustrated electrician meaning for 1995 . --Askedonty (talk) 20:55, 26 November 2017 (UTC)