Subproject B4 Stochastic Structural Analysis

The mechanical properties of compressor blisks are influenced by regeneration processes. High-tech processes enable the repair of components and their reinstallation in the engine. There are various repair designs and regeneration paths. In the subproject B4 efficient methods are developed which support the decision in the regeneration path and improve the service life of components.

Motivation and Objectives

Scheme of the optimization

Decisions in the regeneration process are currently based mainly on subjective criteria. In most cases there are only generally stated repair limits. This engineering decision in the regeneration process will be supported by numerical optimization in the future. The decision about the geometry of the repair is achieved by a parameterized description. The basis for the optimization is a service life calculation, the parameterization of the repair and the use of efficient optimization algorithms.


In the first funding periods it could be shown that geometric imperfections of jet engine blades significantly influence their structural behavior. From the statistical analysis of geometric data, changes in vibration amplitude and blade fatigue life could be identified. This allows the consideration of real geometrical tolerances in the calculating of the service life of the blade.  


First oscillation mode of a compressor blisk

Current Research and Outlook

In the current research of the subproject the optimization potential of repair designs is analyzed. The optimization of blending and patch repairs of compressor blisks is based on parametric models and FE analyses. In addition to the ideal structure, the influence of scatter on the lifetime is considered. Competing repair targets are addressed by multi-objective optimization. The engineering decision about the repair design is supported by robust and reliability-based optimization. The repair designs optimized in the virtual path finally lead to an improved regeneration process in the real path. 

Subproject leader

Prof. Dr.-Ing. habil. Raimund Rolfes
Appelstraße 9a
30167 Hannover
Appelstraße 9a
30167 Hannover


Dr. Christian Gebhardt
Dr. Christian Gebhardt


International Scientific Journal Paper, peer-reviewed

  • Berger, Ricarda; Bruns, Marlene; Ehrmann, Andreas; Haldar, Ayan; Häfele, Jan; Hofmeister, Benedikt et al. (2021): EngiO – Object-oriented framework for engineering optimizationAdvances in Engineering Software 153 (1), S. 102959
    DOI: 10.1016/j.advengsoft.2020.102959
  • Berger, Ricarda; Quaak, Guido; Hofmeister, Benedikt; Gebhardt, Cristian G.; Rolfes, Raimund (2021): Multiobjective Approach Toward Optimized Patch Repairs of Blisk BladesAIAA Journal 22 (5), S. 1–12
    DOI: 10.2514/1.J060723
  • R. Berger, B. Hofmeister, C. G.Gebhardt, R. Rolfes (2020): A two-objective design optimisation approach for blending repairs of damaged compressor blisksAerospace Science and Technology 105, 106022
    DOI: 10.1016/j.ast.2020.106022
  • Rogge T.; Berger, R.; Pohle, L.; Rolfes, R.; Wallaschek, J. (2018): Efficient structural analysis of gas turbine bladesAircraft Eng & Aerospace Tech (Aircraft Engineering and Aerospace Technology) 90 (9), S. 1305–1316
    DOI: 10.1108/AEAT-05-2016-0085
  • Berger, R.; Rogge, T.; Jansen, E.; Rolfes, R. (2016): Probabilistic vibration and lifetime analysis of regenerated turbomachinery bladesAdvances in Aircraft and Spacecraft Science 3 (4), S. 503–521
    DOI: 10.12989/aas.2016.3.4.503
  • Holl, M.; Rogge, T.; Loehnert, S.; Wriggers, P.; Rolfes, R. (2014): 3D multiscale crack propagation using the XFEM applied to a gas turbine bladeComput Mech 53 (1), S. 173–188
    DOI: 10.1007/s00466-013-0900-5

International Conference Paper, peer-reviewed

  • Berger, R.; Hofmeister, B.; Gebhardt, C. G.; Rolfes, R (2019): Parametric Design of Blisk Repairs by Patching Considering High Cycle FatigueIn: ASME (Hg.): Proceedings of the ASME Turbo Expo 2019. Phoenix, USA: American Society of Mechanical Engineers, GT2019-90351
    DOI: 10.1115/GT2019-90351
  • Schwerdt, L.; Berger, R.; Keller, C.; Seume, J.; Rolfes, R.; Panning-von Scheidt, L.; Wallaschek, J. (2017): Influence of Blade Repairs on Compressor Blisk Vibration considering Aerodynamic Damping and MistuningGPPS (Hg.): Proceedings of Global Power and Propulsion Society Conference. Shanghai
  • Hohl, A.; Kriegesmann, B.; Wallaschek, J.; Panning-von Scheidt, L. (2011): The Influence of Blade Properties on the Forced Response of Mistuned Bladed DisksASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, S. 1159–1170
    DOI: 10.1115/GT2011-46826

National Conference Paper, not peer-reviewed

  • Berger, R.; Rogge, T.; Rolfes, R. (2016): Fast Methods for Structural Analysis of Gas Turbine Blades with Manufacturing ImperfectionsDeutscher Luft- und Raumfahrtkongress, Braunschweig 13. - 15. September 2016
  • Rogge, T.; Rolfes, R. (2012): Stochastische Untersuchungen regenerationsbedingter Imperfektionen einer Turbinenschaufel: Modellierung des deterministischen Modells zur effizienten Berechnung des Schwingungs- und Festigkeitsverhaltens5. Dresdner-Probabilistik-Workshop. Dresden, S. 1–11
All publications of the Collaborative Research Centre