A numerical model for fatigue life calculations of surface hardened steel components

This research is focused on the development of a finite element model for simulating the mechanical behaviour and subsequent estimation of fatigue life of surface-hardened, component-like specimens. Such components are used in engineering applications where they are subjected to substantial, often localized, static, and dynamic loads, requiring special attention when modelling their behaviour during operation. To numerically simulate the mechanical behaviour of such components and estimate their fatigue life, it is essential to acquire properties and behaviour of the material itself initially. Estimation methods are thus employed to derive these parameters from more readily available properties obtained from tensile tests or hardness measurements. Hardness distribution is obtained using an analytical model from the literature and it then serves as the foundation for defining material properties and behaviour. Parameters of the cyclic Ramberg-Osgood equation, as well as fatigue Basquin-Coffin-Manson parameters, are calculated using the estimation methods functionally relating them to hardness. By using this approach, a material of surface-hardened component is defined by distinct cyclic stress-strain and strain-life curves for each node of the geometry. Finally, fatigue life calculations for every node are performed by using the constant amplitude loading of the specimen. By analysing the fatigue life distribution across the component, the most critical part can be identified.