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I am taking my first grad level class on stress and elasticity and ran into a bit of a wall. We are dealing with a 3x3 stress tensor which describes the state of stress of a given point. Now various text book problems have questions where given one state describe the state if the element were roateated in some fashion. Now we have just been deriving some formulas and use of the mohr's circle for this but I was thinking "hey why don't i just rotate the tensor". I asked the professor and was told that was perfectly fine if you know how to do it. So since I know linear algebra (undergrad level) and how to deal with vectors and tensors being a glorified vector no sweat.

So i am working on some HW and I try it out. What I find is my answer is incorrect because my matrix is not symetric so obviously something is wrong. Now my approach is wrong as I am told by my professor today but he did not give me much direction as too how to fix so why i am here

What I have been doing is treating the tensor like a matrix created by putting together vectors as rows or columns. I take each of the vectors apply my rotation matrix to them and voila a rotated tensor. This is of course wrong but I am looking for help as too my flaw and more so how I could go about learning how to rotate tensors. I feel it should not be much different than a transofmration of a vector but I could be wrong

any help is much appreciated.

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# Rotating tensors (different from vectors?)

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