Three-Dimensional Stress Analysis of the SAE Keyhole Fatigue Specimen

The results of a three dimensional finite element analysis of the stresses near the notch of the SAE keyhole fatigue specimen are presented. They are compared to plane analyses of the same area and also to data obtained from a three dimensional photoelastic analysis.

The state of stress in the keyhole specimen is neither plane stress nor plane strain. Conditons at the midplane of the notch root are more favorable for early crack initiation than either of the plane formulations.