So I am trying to figure out this shear stress problem that I have no idea how to approach. I have a shaft which is transmisitting a torque. It can be locked to its housing by using a pin which passes through it radially. I need to know that the shaft wont snap when transmitting its torque when unpinned however, and do not know how to solve this problem. I found the stress concentration factor for such a model, but I don't know what equation to use for max or average shear stress, this is beyond my understanding of stress, and beyond all the texts i have my hands on.