Solver Embedded Fatigue 2014-01-0904

This paper presents a fundamental conceptual change to the traditional CAE based fatigue analysis process. Traditional approaches take the responses from a stress solver and these are then transferred into a secondary fatigue analysis step. In this way fatigue is, and always has been, treated as a post processing step. The new conceptual change described in this paper involves combining the two separate tasks into one (stress and fatigue together). This results in a simple, elegant and more powerful Durability Management concept. This new process requires no large data files to be transferred, no complicated file management and it is likely that whole fatigue calculation process can be done in memory. This makes it possible to perform optimization with fatigue life as the constraint. It also facilitates full body fatigue life calculations, including dynamic behavior, for much larger models than was previously possible. Within this new process, fatigue is treated as part of the solve process and not as a post processing operation.

Because of the simpler file management process, and the combined stress-fatigue solution, there will be dramatic reductions in analysis time and process management time. It should be anticipated that where a job takes a week or more to process, it should now be possible in a day or two. There will be a reduction in the time and resources needed for collaboration between different job functions and between different locations because of the simplified analysis definition format (everything in the bulk data file). The combination of optimization with fatigue will result in lighter, more efficient designs. The ability to handle larger models within a dynamic fatigue life calculation will provide greater design confidence.

A solver embedded fatigue process is easier to set up and fully transparent so fatigue analysis will become more accessible to the general analyst. Fatigue life calculations will no longer be the domain of the fatigue expert.

This paper provides a detailed overview of the solver embedded fatigue concept. This new process is demonstrated by application to a typical commercial automotive truck cab model.