Change of basis for deviatoric second order tensors
Dear mechanicians
I remember reading somewhere that someone had a proof of the following:
Given a deviatoric/traceless second order tensor it is possible to find a basis for which all the normal/direct components equal zero.
For 2d this is easy: a basis rotated 45deg wrt. the eigenbasis.
The proof concerned 3d and it may have been Gurtin that had it in one of his books (sometihng tells me "The Linear Theory of Elasticity" (1972) as I don't have access to this one), but I'm not certain.