1. The problem statement, all variables and given/known data is there any normal stress on torsional member? 2. Relevant equations 3. The attempt at a solution My professor showed me a circular rod made up of rubber and she made a rectangular hole on the side of it and asked whether there is any normal stress on the torsional member by showing how the circular rod is twisted when she twist it. I know there must be a shear stress on the torsional member but normal stress? Anyone knows the anwer and explanation for it?