The purpose of this research is to investigate finite element analysis results of two- and three- dimensional models of stepped structures and shouldered shafts with varying fillets and varying size ratios. Combined loading conditions were placed on the models to observe how the loading conditions effect the stress concentration factors.

The results from the finite element analyses were compared to Peterson’s photoelastically determined stress concentration factors. The results were within five percent of Peterson’s results.

For the two- dimensional case, axial and bending loads were applied separately and then superpositioned to evaluate the effect combined loading has on stepped structures. The finite element analysis results from the combined loading agrees to within four percent of the results obtained by calculating the maximum stress at the fillet using Peterson’s stress concentration factors applied to both axial and bending stresses.

For the three- dimensional case, bending and torsion loads were applied separately and then superpositioned to evaluate the effect combined loading would have on shouldered shafts. It was determined for pure bending and pure torsion the finite element analyses are comparable to within five percent of Peterson’s reported stress concentration factors. But under combined loading conditions, the finite element analysis reports a more accurate solution than using Peterson’s stress concentration factors, because Peterson doesn't take into account the hoop stress acting on the shaft.