static analysis of rectangular cross-section

hi, I have a question in simulation on static simulation. I set up a cube and its lenght, height and width are respectively 100mm, 1mm and 40mm. I want to verify the displacement results with the theory and I used the shell element, the shell element and solid element. I found that for beam and solid element, the torsion displacement is not the same as the theory. Do you have any suggestion about this problem? Thank you!

SolidworksSimulation