C6 - Fatigue Behavior

Fatigue Behavior of Sheet-Bulk Metal Formed Workpieces

Project Status: finished

Last Update: 19.01.2021

Members

Proposer

• Dr.-Ing. Dmytro Rodman (until 30.04.2017)
• Prof. Dr.-Ing. Hans Jürgen Maier

Head of Project

• Prof. Dr.-Ing. Hans Jürgen Maier

Researcher

• Dipl.-Ing. Hans-Bernward Besserer (until 31.03.2021)

C6 – Fatigue behavior

Components manufactured by sheet-bulk metal forming have locally inhomogeneous material properties. Due to the cold forming process, locally varying degrees of deformation occur, resulting in differently hardened areas. An additional consequence of cold forming is the introduction of ductile damage in the form of voids in the microstructure. Investigations of the 2nd funding period on specimens from sheet-bulk metal formed components have shown on the one hand that greater work hardening has a positive influence on the service life. On the other hand, an increase of voids due to cyclic loading and thus a negative influence due to increasing ductile damage could be shown. In addition, residual stresses remain in the workpieces as a result of the forming process. Tensile residual stresses favour crack formation and crack propagation during component use and therefore have a negative effect on the fatigue life of the components.

The described material properties have to be taken into consideration for a component layout with respect to their application, for example, as transmission components. Under the influence of cyclic loads, these properties interact with each other and thus require a lifetime analysis of the sheet-bulk metal formed components under "close to service" conditions, since in uniaxial fatigue experiments these interactions cannot be fully taken into account. For this purpose, fatigue tests in a gear test stand are planned in the 3rd funding period, with which geard components can be tested in use and limit loads can be determined.

Working Groups

• Quality Assurance and Quality Management
• Materials

Publications