Fatigue Behavior and Lifetime Prediction

The reliability of components is a central aspect in the qualification of new manufacturing processes with resource-efficient material use. In this context, the focus is on fatigue properties, the experimental verification of which is often the bottleneck for the transition from development to series production. With its modern high-frequency testing laboratory, Fraunhofer IWS offers a wide range of possibilities for a rapid strength assessment of materials and components and thus creates a previously unattainable reduction in the necessary testing times.

Load transmission elements can be found in almost all industrial applications, regardless of the drive concepts used. For this reason, the operationally stable design of these components is a constantly topical issue. At Fraunhofer IWS the focus is on welded, rotationally symmetric components that are subject to superimposed torsional and axial loads. Both the simulation-based design and the experimental fatigue strength verification for the complex stress conditions in the joint area represent an intensive field of research at Fraunhofer IWS.

Fatigue fracture in materials and components is mostly based on notch effects resulting from defects or microstructural irregularities. A load-compliant design of structural components is therefore only possible if these strength-reducing features are taken into account. This aspect increases in importance for additively built or joined structures. Therefore, at Fraunhofer IWS service life estimates are always based on experimental correlations between the fatigue strength and the crack-inducing elements of a structure. The focus here is not necessarily always on “as good as possible“, but much more often on “as good as necessary“.