On the press fit of a crankpin into a circular web in pressed-up crankshafts

Abstract

The contact stresses induced by press-fitting a crankpin into a crankweb bore in pressed-up crankshafts are analysed for crankwebs possessing a circular geometry. The three-dimensional nature of this problem is reduced to a plane model, where the crankweb is described in terms of an eccentrically bored disc of uniform thickness, while the crankpin is idealized as an annular ring. Two different approaches are employed. Firstly, an elastic plane finite element analysis is carried out for this contact problem. Secondly, based upon the results of the numerical study, three variously approximated plane analytical models are developed. The contact pressure and the circumferential stress by the web bore are investigated, as well as the transmissible torque, where normalized diagrams are provided exploring a variety of disc-type crankweb geometries. Finally, selected three-dimensional finite element results are discussed, which highlight the limits of a plane model.