Fretting fatigue of single crystal/polycrystalline nickel subjected to blade/disk contact loading

H. Murthy, Daniel B. Garcia, John F. Matlik, Thomas N. Farris

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Two bodies are said to be in fretting contact when they are clamped together under the action of a normal force and see an oscillatory motion of small amplitudes at the contact interface due to the effect of shear force and bulk stress. The contact stresses that drive crack nucleation are very sensitive to the shape of the contacting surfaces and the coefficient of friction. To have an understanding of fretting at the contacts in engine components, it is important to simulate similar temperature, load and contact conditions in the laboratory and develop tools to analyze the contact conditions. The efforts made at simulating the temperature and load conditions typical to the engine hardware and the development of a robust mechanics based tool for life prediction are presented. The features of the rig include a combination of an efficient cooling mechanism using water and an insulation mechanism using ceramic blocks and sheets. The rig has been used to conduct an initial set of experiments using single crystal nickel (SCN) specimens and IN100 pads, and was found to function well under the operating temperature and load conditions. Crystallographic orientations contribute significantly to evaluation of the contact stress field. To perform an accurate analysis of anisotropic contact, a clear understanding of the material axes orientations must be maintained. A method for determining axes orientation using a Lauè diffraction method is described. Preliminary fractographic observations revealed that the fracture occurs along the 〈111〉 plane. Close observation of the crack initiation site revealed that the crack initiated at the edge of contact on a plane perpendicular to the contact surface.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalActa Astronautica
Volume57
Issue number1
DOIs
StatePublished - Jul 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering

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