Fatigue Life Calculation Concepts for Structures with Inhomogenous Strength Properties

A fast transfer of new manufacturing- and material technologies to actual design use is only to be expected if calculation concepts exist, which allow an easy estimation of the parts’ strength properties. This Collaborative Research Project (CRP) will develop new manufacturing and joining techniques to create high strength structures by adjusting the local strength properties of parts. These types of structures are usually loaded dynamically. To specifically optimise the fatigue behaviour, stiffness and weight of a structure, the influences of locally strengthening manufacturing processes must be considered in the fatigue life calculation concept. It is the goal of this project to include a simulation of the fatigue behaviour in the process simulation of manufacturing. Recently research on the influence of local strengthening by cold forming on fatigue life was undertaken in cooperation within another research project. The fatigue life calculation of sheet metal structures can be based on a calculation concept developed in CRP 362, subproject C5, which takes into account the influence of forming, [1,2,3,4]. This concept shall be extended to incorporate the effects of local martensite forming in the cold formed areas.