Rißfortschritt in elastisch-plastisch beanspruchten Kerbbereichen bei Schwingbelastung mit veränderl

FKM 1995
Project No. 145-4

Final report

Abstract:
In this research project, a J-integral related crack propagation model has been developed with special consideration of crack opening and crack closing behavior. It was possible to numerically describe the crack propagation phase within the notch region for single-stage, two-stage and service load tests on notched disks. This area of crack propagation is of particular importance, as a considerable part of the overall service life of a component is often determined by the growth of cracks in notches. For this purpose, formulas, algorithms and approximation formulas first had to be developed to describe the crack opening and closing behavior and to calculate the J-integral of cracks in notches. These were compared with experiments for crack opening and with two- and three-dimensional elastic-plastic FE calculations for the J-integrals. Good to very good agreement was achieved in both cases. The crack propagation concept allows the calculation of the crack propagation life from a given initial crack configuration (crack type, length, depth) to a critical crack configuration. It is designed in such a way that it immediately follows the crack initiation phase. It therefore includes crack propagation inside and outside (long crack growth) of the notch area. If you are interested in the overall service life, the initial crack configuration, which is important for the start of the crack propagation calculation, is taken from the crack initiation calculation. The total service life is then the sum of the crack initiation and crack propagation service life. The crack propagation curves determined with a crack propagation calculation program developed during the course of this research project were compared with the experimentally determined crack propagation curves. The results show good to very good agreement for the one- and two-stage tests and for the service load. Even the crack propagation lifetimes of the notched disks made of AIMg4.5Mn can be predicted well, although neither approximate formulas for calculating the stress intensity factor K nor for determining the J-integral for elliptical notches exist.


Scope of report:
84 p., 47 fig., 14 tab., 56 lil

Appendix:
66 p., 61 fig., 1 tab.

Start of work:
01.07.1990

End of work:
31.12.1993

Funding body:
Stiftung Stahlanwendungsforschung, A 47

Research unit:
Fachgebiet Werkstoffmechanik, Technische Hochschule Darmstadt
Head:
Prof. Dr.-lng. T. Seeger

Editors and authors:
Dipl.-lng. M. Dankert, Dipl.-lng. G. Savaidis

Chairman of the working group:
Dr.-lng. A. Bäumel Mercedes-Benz AG, Sindelfingen

Chairman of the advisory board:
Prof. Dr.-lng. H. Kipphan, Heidelberger Druckmaschinen AG, Heidelberg