In many engineering situations components frequently have to withstand more than one type of load.
Shafts often have to withstand torque and bending moments.
To solve this type of design problem the components are assumed to behave in a linear manner and superposition is used. The stresses due to each type of loading are determined in turn and then combined using appropriate equations or Mohr's circle. In some configurations it will not be obvious where the maximum combined shear stress occurs, in these cases it will be necessary to check the combined stresses at a number of locations. For the example of a uniform solid shaft, diameter d, subject to torsion T and tension P, the maximum shear stress is constant at all points on the surface. Return to Module Introduction David J Grieve, September 1998.