Nonlinear Finite Element Analysis of a Sharp Radius on the Shank of a Ring Locked Stud

This paper documents an investigation of the effect of a sharp radius on the shank of a ring locked stud. An industry specification for studs does not define a minimum size for the radius and very sharp radii have been found during inspection of some studs. Finite element analysis (FEA) is used to evaluate the stud as part of an assembled joint subject to fatigue loading. A parametric study is conducted, and high-fidelity modeling is adopted to correlate the FEA results with stud testing results. After a validated FEA model is confirmed, the elastic-plastic stress strain curve is applied in the FEA model. Three sizes of the radius are introduced in the model to evaluate the radius size effect on the vibratory stress under operational loads. The evaluation demonstrates that the radius size has a significant impact on its vibratory stress which in turn affects the calculated fatigue life.