Elevated temperature fretting of turbine materials subjected to engine type-loading

TY - JOUR

T1 - Elevated temperature fretting of turbine materials subjected to engine type-loading

AU - Murthy, H.

AU - Farris, T. N.

PY - 2003

Y1 - 2003

N2 - 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 contracting 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.

AB - 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 contracting 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.

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M3 - Conference article

SN - 0273-4508

VL - 2

SP - 1148

EP - 1158

JO - Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

JF - Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

T2 - 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

Y2 - 7 April 2003 through 10 April 2003

ER -