Finding stress at an angle for a rotating part

Hi,

We need to find the stress when the part is twisted at an angle. It's shown in the capture-1 below that a motor powers the pocket at one end, while the other end has a stopper. load (capture 2) & constrains (capture 3), kindly advise me on how to calculate the stress values at various angles? 

Plastic is the material that is used & currently I am using Creo 7

Thanks