Cyclic Mixed-Mode Crack Propagation due to Time-Dependent Multiaxial Loading in Jet Engines

Abstract:

Components in jet engines are subject to time-dependent multiaxial loading. This creates a time-varying mixed-mode stress state at the crack tip. Mixed-mode loading leads to out-of-plane crack propagation and has been treated in previous articles [1,2]. This paper concentrates on coping with the time-dependent character. Key issues are the crack propagation rate and the crack propagation direction in three-dimensional space. In order to determine the prevalent crack propagation direction the dominant loading case is determined based on its crack propagation rate. Then, a mixed-mode equivalent K-factor is calculated for all other loading cases based on the closeness of their associated crack propagation direction with the dominant one. Subsequently, a cycle extraction is performed on the crack propagation rate for all loading cases. The extracted cycles are processed based on their mimimum and maximum equivalent K-factor and the maximum temperature. The mission crack propagation rate consists of the sum of the rate of all extracted cycles.

• Periodical: Key Engineering Materials (Volumes 488-489)
• Pages: 93-96
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.488-489.93
• Online since: September 2011
• Authors: Guido Dhondt
• Keywords: Cycle Extraction, Cyclic Crack Propagation, Mission Analysis, Mixed-Mode

References

[1] G. Dhondt: Key Engineering (2003), pp.251-252, 209.

[2] M. Schöllmann, G. Kullmer, M. Fulland and H.A. Richard, in: Proc. of 6th Int. Conf. on Biaxial/Multiaxial Fatigue & Fracture, edited by M. de Freitas (2001), Lissabon, pp.589-596.

[3] S.D. Downing and D.F. Socie Int. J. Fatigue (1982), pp.31-40.