Fatigue optimization of an induction hardened shaft under combined loading

Abstract

An integrated procedure, combining finite element modeling and fatigue analysis methods, is developed and applied to the fatigue optimization of a notched, induction hardened, steel shaft subjected to combined bending and torsional loading. Finite element analysis is used first to develop unit-load factors for generating stress-time histories, and then, employing thermo-elastic techniques, to determine the residual stresses resulting from induction hardening. These stress fields are combined using elastic superposition, and incorporated in a fatigue analysis procedure to predict failure location and lifetime. Through systematic variation of geometry, processing, and loading parameters, performance surfaces are generated from which optimum case depths for maximizing shaft fatigue performance are determined. General implications of such procedures to the product development process are discussed.