Microstructure-sensitive fatigue lifetime assessment considering forming history effects (COMInt 2)

• Applicants: Professor Dr.-Ing. Thomas Bergs; Professor Dr.-Ing. Sebastian Münstermann
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing ; Engineering Design, Machine Elements, Product Development
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 432053466

Utilizing high safety factors in component design is a common approach to prevent fatigue-related issues. However, the correspondingly increased use of materials is in direct contradiction to the resource efficiency required in the context of climate change. Ensuring component safety while minimizing the use of materials is only insufficiently possible with current design methods. To manufacture resource-efficient components, novel approaches to predicting service life are essential. Fatigue mechanism modeling is pivotal in designing cyclically loaded components. Yet, the presence of localized variations in microstructure and surface integrity, coupled with resulting performance fluctuations, complicates such modeling efforts. In cold forming processes, performance gains are achievable through work hardening and favorable fiber flow. Each forming step induces local changes in material properties rooted in microstructural evolution, including increased dislocation density or texture development. However, leveraging these mechanisms optimally is constrained by incomplete understanding of deformation-related material changes' effects on cyclic loads. The research project aims to establish correlations among macroscopic deformation levels, microstructural evolution, and workpiece and component performance. This initiative seeks to comprehend material changes and their impact on cyclic load-bearing capacity throughout component manufacturing and usage. To achieve this goal, the project is developing methods to quantitatively assess the influence of forming history on component performance under cyclic loading. These methodological advancements will be validated through a model process chain. Multiscale, coupled simulation approaches, combined with optimization methods, will identify tailored parameters for the model process chain to enhance performance. The effectiveness of this novel concept will be demonstrated by analyzing component behavior along the production chain, which involves full forward extrusion followed by mechanical surface treatment using deep rolling.

• DFG Programme: Research Grants