Flexibility of shafts with abrupt changes of section

The calculation of deflections of shafts by simple bending theory can incur errors if it is applied where the shafts are stepped with large and abrupt changes of section. Following an experimental check, the finite element displacement method was used for an investigation into the flexural properties of such shafts, particular attention being paid to the relationship between the step geometry and the centre line deflection curves.It is shown that centre line deflections of a stepped shaft may be calculated by using simple bending theory in conjunction with an appropriate equivalent variable second moment of area for sections of shaft in the region of the step. Graphical data on the equivalent second moment of area is provided for a wide range of step length/basic shaft diameter and step diameter/basic shaft diameter ratios.