Life time prediction of metallic materials with the Discrete-Element-Method
The numerical simulation of fatigue and the prediction of the life time of structures is more than 50 years after the introduction of the Finite-Element-Method (FEM) still a problem. Another numerical method, older than the Finite Element idea, is the Discrete-Element-Method (DEM), with which a material can be represented as a continuum as well as a discontinuum. Over the last few years engineers have become very fascinated by this method, since it enables a very realistic fracture modelling. Furthermore it is also possible to make life time predictions with the DEM. This paper shows a new way of obtaining S–N curves for metallic materials, affected by mechanical loads. For the numerical simulation of life time a virtual specimen is represented by Discrete Elements. When using this method, no initial cracks or initial crack lengths are needed.
Materials always show a variation in their properties. Since the discrete variation of the material parameters has an influence on the mechanical behaviour of the structure and its life time, statistical aspects are also discussed briefly in this paper. These stochastically distributed microscopic effects are included in the DEM model.
Keywords: Discrete-Element-Method, Life time, Fatigue, S–N curves, Wöhler curves