4. (a) (b) A solid shaft of 40 mm diameter is fixed at one end and subjected to two forces at the free end as shown in Figure 4. Express the reactions at the fixed end in terms of F and show their orientations on a sketch. (8 marks) Express the principal stresses and maximum shearing stress at point A in terms of F. (11 marks) If point A is the most critical point, determine the respective maximum load F for failure as predicted by maximum shearing stress, maximum distortion energy and maximum normal stress yield criteria. The yield stress of the material is 250 MPa. (6 marks) Fixed end Z K Rigid bar 240 mm DE 360 mm Figure 4 3 F 12 F