Vorhaben Nr. A 143/99 Auswirkungen eines dreiachsigen Spannungszustandes auf das Verformungsverhalte

FKM 2004
Booklet No. 278
Project No. 244


For the use of large forgings in turbines and generators, it is necessary to safeguard the components with regard to crack initiation and propagation on the basis of modern ultrasonic testing in conjunction with the specific component stresses and the existing material properties if any manufacturing defects occur. The aim of the project is to create a reliable level of knowledge about the propagation behavior of group defects under practical conditions. To achieve this objective, both experimental investigations on flawed specimens under uniaxial and multiaxial loading and extensive numerical investigations were carried out. Various 3D and 2D meshes with simulated defects were generated. The stress and deformation states in the area of the defects were determined with the aid of the linear-elastic calculations simulated under uniaxial and multiaxial loading and simulated according to the Norton-Bailey creep law. Based on the numerical analyses, a criterion for assessing the interaction between two defects as a function of the defect size ratio and the distance was developed and verified using the experimental results. On the basis of the project results, a recommendation for the assessment of ultrasonic indicators of different types was drawn up, taking multi-axial stresses into account. This provides a tool that allows the extended assessment of group defects using fracture mechanics methods. Scope of report:
198 pages Start of work:
01.01.2000 End of work:
31.12.2002 Funding body:
AVIF-No. A143/99 Research unit:
Staatliche Materialprüfungsanstalt (MPA) Universität Stuttgart Head:
Prof. Dr.-lng. habil. Eberhard Roos Editor and author:
Dipl.-lng. Christina Weichert Chairman of the working group:
Dr.-lng. Claus Gerdes ALSTOM Power, Baden Chairman of the advisory board:
Dipl.-lng. W. Keppel, Alstom Power Generation, Mannheim