Schwingfestigkeit von geschweißten Komponenten unter komplexen elasto-plastischen, mehrachsigen Verformungen

Generally, areas of components with notches or geometrical transitions are critical because of the resulting stress/strain concentrations. In these areas due to the stress-gradients and constraint local deformations are displacement controlled even if the material's yield stress is exceeded, as long as the deformations are below the structural yield point. Therefore, load controlled tests in the elasto-plastic region with unnotched specimens from ductile materials under combined axial loading and torsion are not suitable for the interpretation of component's behaviour because of uncontrolled local deformations. Thus, the influence of multiaxial stress/strain states on the fatigue behaviour of a component under elasto-plastic deformations can be determined reliably with unnotched specimens only by deformation controlled tests, if cyclic creep is not expected in critical areas.