A component with a radius transition is attached to a rigid wall at point A.  A moment M is applied at point C.  The component thickness is 20mm and the radius is 5 mm. 

Part A: The component is made of a brittle material with yield strength of 60 MPa and an ultimate strength of 75 MPa.  Find the max permitted moment M for a factor of safety equal to 3 at the transition section B.

Part B: Engineers are considering making this component from a ductile material.  If the worst case state of stress (happens in the ductile material near the rigid wall transition at point A) is shown:

Determine the factor of safety relative to the maximum shear stress theory of the proposed material if it's yield strength is 90 MPa.