charlotte Vieillard - Academia.edu (original) (raw)

Papers by charlotte Vieillard

Research paper thumbnail of An experimental and theoretical study of surface rolling contact fatigue damage progression in hybrid bearings with artificial dents

Wear, Oct 1, 2016

An experimental study followed by modeling is carried out for pre-dented hybrid rolling bearings ... more An experimental study followed by modeling is carried out for pre-dented hybrid rolling bearings to observe the raceway surface damage evolution and to try to understand its behavior. The experiments and modeling are repeated in similar all-steel bearings and conditions for comparison purposes. The results show that hybrid bearings tend to re-accommodate the dent raised edges on the steel surface by mild wear and plastic deformation and this stabilizes the local pressures much faster than all-steel bearings. Followed by a lower boundary friction coefficient, when the lubricated oil is broken by the surface features, hybrid bearings give still longer dent lives than the all-steel bearings, even though the conditions are at equal bearing load (which means higher stresses in the hybrid bearings).

Research paper thumbnail of Grease Performance in Ball and Roller Bearings for All-Steel and Hybrid Bearings

Tribology transactions, Dec 8, 2021

Grease life in hybrid bearings is longer than that in all-steel bearings. This will be shown in t... more Grease life in hybrid bearings is longer than that in all-steel bearings. This will be shown in this paper by means of grease life tests with a large number of greases for both Deep Groove Ball Bearings (DGBB) and Cylindrical Roller bearings (CRB). The results show that grease life for hybrid bearings is always larger than that for equivalent all-steel bearings and that this varies between a factor 2 and 9 depending on the grease type that is used. For cylindrical roller bearings grease life does not increase with decreasing speed below a minimum value. However, also at these relatively low speeds, hybrid bearings give a longer grease life than all-steel bearings.

Research paper thumbnail of Modelling the criticality of silicon nitride surface imperfections under rolling and sliding contact

Tribology International, Aug 1, 2020

Ceramic rolling elements of hybrid bearings may initially include surface imperfections. In order... more Ceramic rolling elements of hybrid bearings may initially include surface imperfections. In order to provide reliable operation of a bearing, the criticality of such imperfections under rolling contact fatigue is examined by defining them as Star features: intersecting semi-elliptical surface cracks. Parametric study is conducted using Finite Element Method and discussed with help of previously published experimental observations. The effects of the Star feature morphology and configuration, contact pressure and crack face friction are investigated in terms of stress intensity factors. Possible crack propagation scenarios are explained in the present study.

Research paper thumbnail of Characterization and modelling of the degradation of silicon nitride balls with surface missing-material defects under lubricated rolling contact conditions

Wear, Mar 1, 2018

Hybrid bearings in which ceramic rolling elements are used in combination with hardened steel rin... more Hybrid bearings in which ceramic rolling elements are used in combination with hardened steel rings outperform the conventional full-steel bearings in some demanding applications where high speed, high temperature, electric current, and thin-film or medium lubrication are involved. Despite the continued effort and progress made to improve the toughness, ceramics are regarded as brittle solids that can suffer in general from lack of damage tolerance in the form of sensitivity to pre-existing features that are seen as being potentially harmful. Under specific conditions, these imperfections may become critical for the reliability of hybrid bearings. This paper reports on a study of the degradation of silicon nitride ceramic balls, caused by surface missingmaterial (MM) defects under lubricated rolling contact conditions. Rolling contact fatigue test is conducted on the ceramic balls containing artificial defects of different configuration and sizes. Numerical simulation by means of finite element analysis indicates that the lubricant entrapped inside the MM cavity will be pressurized under rolling contact. The hydraulic pressure of the entrapped lubricant can result in significant tensile stress at the corner of the cavity that may cause crack initiation, initial crack propagation, and eventual spalling of the ball surface. Such a degradation mechanism is confirmed by the characteristics of the fatigue damage observed from the tested balls. Based on the understanding of the failure mechanism, a model based on the nonlocal approach to crack initiation at a V-notch is developed to describe the damage tolerance of the silicon nitride balls with the MM defects of specific geometry with respect to the rolling contact load. The prediction of the tolerance limits agrees well with the endurance limits of the silicon nitride balls tested under lubricated rolling contact conditions. This research has contributed to a fundamental understanding on what type and size of the MM defects can be tolerated in hybrid bearings in relation to used application running conditions.

Research paper thumbnail of Finite elements based approaches for the modelling of radial crack formation upon Vickers indentation in silicon nitride ceramics

Journal of The European Ceramic Society, Nov 1, 2019

By having superior properties silicon nitride ceramics can be considered as the state-of-the-art ... more By having superior properties silicon nitride ceramics can be considered as the state-of-the-art material in the bearing industry. Vickers indentation of this material is typically accompanied by formation of cracks visible on surface. Two Finite Elements models are developed in the current work: the first model is based on fracture mechanics and the second on cleavage stress criterion. Plastic behavior of silicon nitride is included in the modeling, and since little is known on the plasticity of this material, the Drucker-Prager model (used for nonmetallic materials) along with the classical J 2-plasticity are explored. The results of the fracture mechanics based model correlate well with experimental results in terms of surface crack length. The numerical results in terms of the morphology of the indented zone (including cracks and plastic zone) are provided by the stress criterion based model, and these results correlate well too, with the experimental data.

Research paper thumbnail of Specification of a micro-transgranular fracture parameter

The micro-transgranular fracture calibration with a help of an efficient parallel numerical tool ... more The micro-transgranular fracture calibration with a help of an efficient parallel numerical tool is demonstrated in this poster.

Research paper thumbnail of Dynamic indentation induced damage in silicon nitride

This poster shows simulation results of trasngranular fracture percentage in the ceramic microstr... more This poster shows simulation results of trasngranular fracture percentage in the ceramic microstructure under tensile loading. Moreover, the crack face roughness was investigated for microstructures with different grain sizes.

Research paper thumbnail of Palier en métal léger et matériau céramique

L'invention concerne un palier comprenant au moins une bague de roulement (1, 2, 4, 5, 6) sur... more L'invention concerne un palier comprenant au moins une bague de roulement (1, 2, 4, 5, 6) sur laquelle un chemin de roulement (7, 8) est forme. La bague de roulement (1, 2, 4, 5, 6) comprend au moins un premier composant (1, 5, 6) essentiellement constitue d'un materiau metallique leger et au moins un second composant (2, 4) essentiellement constitue d'un materiau en ceramique completement dense. Le premier composant (1, 5, 6) et le second composant (2, 4) sont des entites separees reliees ensemble, et le second composant (2, 4) comprend au moins une partie du chemin de roulement (7, 8).

Research paper thumbnail of Lager mit leichtem metall- und keramikmaterial

Research paper thumbnail of Grease Performance in Ball and Roller Bearings for All-Steel and Hybrid Bearings

Tribology Transactions, 2021

Grease life in hybrid bearings is longer than that in all-steel bearings. This will be shown in t... more Grease life in hybrid bearings is longer than that in all-steel bearings. This will be shown in this paper by means of grease life tests with a large number of greases for both Deep Groove Ball Bearings (DGBB) and Cylindrical Roller bearings (CRB). The results show that grease life for hybrid bearings is always larger than that for equivalent all-steel bearings and that this varies between a factor 2 and 9 depending on the grease type that is used. For cylindrical roller bearings grease life does not increase with decreasing speed below a minimum value. However, also at these relatively low speeds, hybrid bearings give a longer grease life than all-steel bearings.

Research paper thumbnail of Modelling the criticality of silicon nitride surface imperfections under rolling and sliding contact

Tribology International, 2020

Ceramic rolling elements of hybrid bearings may initially include surface imperfections. In order... more Ceramic rolling elements of hybrid bearings may initially include surface imperfections. In order to provide reliable operation of a bearing, the criticality of such imperfections under rolling contact fatigue is examined by defining them as Star features: intersecting semi-elliptical surface cracks. Parametric study is conducted using Finite Element Method and discussed with help of previously published experimental observations. The effects of the Star feature morphology and configuration, contact pressure and crack face friction are investigated in terms of stress intensity factors. Possible crack propagation scenarios are explained in the present study.

Research paper thumbnail of Characterization and modelling of the degradation of silicon nitride balls with surface missing-material defects under lubricated rolling contact conditions

Wear, 2018

Hybrid bearings in which ceramic rolling elements are used in combination with hardened steel rin... more Hybrid bearings in which ceramic rolling elements are used in combination with hardened steel rings outperform the conventional full-steel bearings in some demanding applications where high speed, high temperature, electric current, and thin-film or medium lubrication are involved. Despite the continued effort and progress made to improve the toughness, ceramics are regarded as brittle solids that can suffer in general from lack of damage tolerance in the form of sensitivity to pre-existing features that are seen as being potentially harmful. Under specific conditions, these imperfections may become critical for the reliability of hybrid bearings. This paper reports on a study of the degradation of silicon nitride ceramic balls, caused by surface missingmaterial (MM) defects under lubricated rolling contact conditions. Rolling contact fatigue test is conducted on the ceramic balls containing artificial defects of different configuration and sizes. Numerical simulation by means of finite element analysis indicates that the lubricant entrapped inside the MM cavity will be pressurized under rolling contact. The hydraulic pressure of the entrapped lubricant can result in significant tensile stress at the corner of the cavity that may cause crack initiation, initial crack propagation, and eventual spalling of the ball surface. Such a degradation mechanism is confirmed by the characteristics of the fatigue damage observed from the tested balls. Based on the understanding of the failure mechanism, a model based on the nonlocal approach to crack initiation at a V-notch is developed to describe the damage tolerance of the silicon nitride balls with the MM defects of specific geometry with respect to the rolling contact load. The prediction of the tolerance limits agrees well with the endurance limits of the silicon nitride balls tested under lubricated rolling contact conditions. This research has contributed to a fundamental understanding on what type and size of the MM defects can be tolerated in hybrid bearings in relation to used application running conditions.

Research paper thumbnail of Finite elements based approaches for the modelling of radial crack formation upon Vickers indentation in silicon nitride ceramics

Journal of the European Ceramic Society, 2019

By having superior properties silicon nitride ceramics can be considered as the state-of-the-art ... more By having superior properties silicon nitride ceramics can be considered as the state-of-the-art material in the bearing industry. Vickers indentation of this material is typically accompanied by formation of cracks visible on surface. Two Finite Elements models are developed in the current work: the first model is based on fracture mechanics and the second on cleavage stress criterion. Plastic behavior of silicon nitride is included in the modeling, and since little is known on the plasticity of this material, the Drucker-Prager model (used for nonmetallic materials) along with the classical J 2-plasticity are explored. The results of the fracture mechanics based model correlate well with experimental results in terms of surface crack length. The numerical results in terms of the morphology of the indented zone (including cracks and plastic zone) are provided by the stress criterion based model, and these results correlate well too, with the experimental data.

Research paper thumbnail of In-situ observation of crack propagation in silicon nitride ceramics

Procedia Structural Integrity, 2017

During their operation, modern aircraft engine components are subjected to increasingly demanding... more During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data.

Research paper thumbnail of Observation of subsurface rolling contact fatigue cracks in silicon nitride and comparison of their location to Hertzian contact subsurface stresses

International Journal of Fatigue, 2017

From lubricated rolling contact tests on silicon nitride rolling elements, genuine subsurface fat... more From lubricated rolling contact tests on silicon nitride rolling elements, genuine subsurface fatigue process from the Si3N4 microstructure was demonstrated and visualized for the first time by testing two different microstructure quality levels. Subsurface fatigue cracks initiating at microstructure features were found to be associated with local orthogonal shear stresses from the Hertzian stress field. All fatigue cracks displayed evidence of Mode II and III crack type propagation with an angle orientation that conformed to the shear stress direction.

Research paper thumbnail of Cavitation erosion in silicon nitride: Experimental investigations on the mechanism of material degradation

Tribology International, 2010

... B Karunamurthy a * , M Hadfield a , C Vieillard b , G Morales b . a Sustainable Design Resear... more ... B Karunamurthy a * , M Hadfield a , C Vieillard b , G Morales b . a Sustainable Design Research Centre, School of Design, Engineering and Computing ... [5] Scott D, Blackwell J, et al., 1971, Silicon nitride as a rolling bearing material a preliminary assessment, Wear, Vol 17(1) 73 ...

Research paper thumbnail of Large ceramic component and method of manufacture

Research paper thumbnail of Bearing and method of inhibiting crack propagation in a bearing component

Research paper thumbnail of Method for Manufacturing Ceramic Components

Research paper thumbnail of Bearing with light weight metal and ceramic material

Research paper thumbnail of An experimental and theoretical study of surface rolling contact fatigue damage progression in hybrid bearings with artificial dents

Wear, Oct 1, 2016

An experimental study followed by modeling is carried out for pre-dented hybrid rolling bearings ... more An experimental study followed by modeling is carried out for pre-dented hybrid rolling bearings to observe the raceway surface damage evolution and to try to understand its behavior. The experiments and modeling are repeated in similar all-steel bearings and conditions for comparison purposes. The results show that hybrid bearings tend to re-accommodate the dent raised edges on the steel surface by mild wear and plastic deformation and this stabilizes the local pressures much faster than all-steel bearings. Followed by a lower boundary friction coefficient, when the lubricated oil is broken by the surface features, hybrid bearings give still longer dent lives than the all-steel bearings, even though the conditions are at equal bearing load (which means higher stresses in the hybrid bearings).

Research paper thumbnail of Grease Performance in Ball and Roller Bearings for All-Steel and Hybrid Bearings

Tribology transactions, Dec 8, 2021

Grease life in hybrid bearings is longer than that in all-steel bearings. This will be shown in t... more Grease life in hybrid bearings is longer than that in all-steel bearings. This will be shown in this paper by means of grease life tests with a large number of greases for both Deep Groove Ball Bearings (DGBB) and Cylindrical Roller bearings (CRB). The results show that grease life for hybrid bearings is always larger than that for equivalent all-steel bearings and that this varies between a factor 2 and 9 depending on the grease type that is used. For cylindrical roller bearings grease life does not increase with decreasing speed below a minimum value. However, also at these relatively low speeds, hybrid bearings give a longer grease life than all-steel bearings.

Research paper thumbnail of Modelling the criticality of silicon nitride surface imperfections under rolling and sliding contact

Tribology International, Aug 1, 2020

Ceramic rolling elements of hybrid bearings may initially include surface imperfections. In order... more Ceramic rolling elements of hybrid bearings may initially include surface imperfections. In order to provide reliable operation of a bearing, the criticality of such imperfections under rolling contact fatigue is examined by defining them as Star features: intersecting semi-elliptical surface cracks. Parametric study is conducted using Finite Element Method and discussed with help of previously published experimental observations. The effects of the Star feature morphology and configuration, contact pressure and crack face friction are investigated in terms of stress intensity factors. Possible crack propagation scenarios are explained in the present study.

Research paper thumbnail of Characterization and modelling of the degradation of silicon nitride balls with surface missing-material defects under lubricated rolling contact conditions

Wear, Mar 1, 2018

Hybrid bearings in which ceramic rolling elements are used in combination with hardened steel rin... more Hybrid bearings in which ceramic rolling elements are used in combination with hardened steel rings outperform the conventional full-steel bearings in some demanding applications where high speed, high temperature, electric current, and thin-film or medium lubrication are involved. Despite the continued effort and progress made to improve the toughness, ceramics are regarded as brittle solids that can suffer in general from lack of damage tolerance in the form of sensitivity to pre-existing features that are seen as being potentially harmful. Under specific conditions, these imperfections may become critical for the reliability of hybrid bearings. This paper reports on a study of the degradation of silicon nitride ceramic balls, caused by surface missingmaterial (MM) defects under lubricated rolling contact conditions. Rolling contact fatigue test is conducted on the ceramic balls containing artificial defects of different configuration and sizes. Numerical simulation by means of finite element analysis indicates that the lubricant entrapped inside the MM cavity will be pressurized under rolling contact. The hydraulic pressure of the entrapped lubricant can result in significant tensile stress at the corner of the cavity that may cause crack initiation, initial crack propagation, and eventual spalling of the ball surface. Such a degradation mechanism is confirmed by the characteristics of the fatigue damage observed from the tested balls. Based on the understanding of the failure mechanism, a model based on the nonlocal approach to crack initiation at a V-notch is developed to describe the damage tolerance of the silicon nitride balls with the MM defects of specific geometry with respect to the rolling contact load. The prediction of the tolerance limits agrees well with the endurance limits of the silicon nitride balls tested under lubricated rolling contact conditions. This research has contributed to a fundamental understanding on what type and size of the MM defects can be tolerated in hybrid bearings in relation to used application running conditions.

Research paper thumbnail of Finite elements based approaches for the modelling of radial crack formation upon Vickers indentation in silicon nitride ceramics

Journal of The European Ceramic Society, Nov 1, 2019

By having superior properties silicon nitride ceramics can be considered as the state-of-the-art ... more By having superior properties silicon nitride ceramics can be considered as the state-of-the-art material in the bearing industry. Vickers indentation of this material is typically accompanied by formation of cracks visible on surface. Two Finite Elements models are developed in the current work: the first model is based on fracture mechanics and the second on cleavage stress criterion. Plastic behavior of silicon nitride is included in the modeling, and since little is known on the plasticity of this material, the Drucker-Prager model (used for nonmetallic materials) along with the classical J 2-plasticity are explored. The results of the fracture mechanics based model correlate well with experimental results in terms of surface crack length. The numerical results in terms of the morphology of the indented zone (including cracks and plastic zone) are provided by the stress criterion based model, and these results correlate well too, with the experimental data.

Research paper thumbnail of Specification of a micro-transgranular fracture parameter

The micro-transgranular fracture calibration with a help of an efficient parallel numerical tool ... more The micro-transgranular fracture calibration with a help of an efficient parallel numerical tool is demonstrated in this poster.

Research paper thumbnail of Dynamic indentation induced damage in silicon nitride

This poster shows simulation results of trasngranular fracture percentage in the ceramic microstr... more This poster shows simulation results of trasngranular fracture percentage in the ceramic microstructure under tensile loading. Moreover, the crack face roughness was investigated for microstructures with different grain sizes.

Research paper thumbnail of Palier en métal léger et matériau céramique

L'invention concerne un palier comprenant au moins une bague de roulement (1, 2, 4, 5, 6) sur... more L'invention concerne un palier comprenant au moins une bague de roulement (1, 2, 4, 5, 6) sur laquelle un chemin de roulement (7, 8) est forme. La bague de roulement (1, 2, 4, 5, 6) comprend au moins un premier composant (1, 5, 6) essentiellement constitue d'un materiau metallique leger et au moins un second composant (2, 4) essentiellement constitue d'un materiau en ceramique completement dense. Le premier composant (1, 5, 6) et le second composant (2, 4) sont des entites separees reliees ensemble, et le second composant (2, 4) comprend au moins une partie du chemin de roulement (7, 8).

Research paper thumbnail of Lager mit leichtem metall- und keramikmaterial

Research paper thumbnail of Grease Performance in Ball and Roller Bearings for All-Steel and Hybrid Bearings

Tribology Transactions, 2021

Grease life in hybrid bearings is longer than that in all-steel bearings. This will be shown in t... more Grease life in hybrid bearings is longer than that in all-steel bearings. This will be shown in this paper by means of grease life tests with a large number of greases for both Deep Groove Ball Bearings (DGBB) and Cylindrical Roller bearings (CRB). The results show that grease life for hybrid bearings is always larger than that for equivalent all-steel bearings and that this varies between a factor 2 and 9 depending on the grease type that is used. For cylindrical roller bearings grease life does not increase with decreasing speed below a minimum value. However, also at these relatively low speeds, hybrid bearings give a longer grease life than all-steel bearings.

Research paper thumbnail of Modelling the criticality of silicon nitride surface imperfections under rolling and sliding contact

Tribology International, 2020

Ceramic rolling elements of hybrid bearings may initially include surface imperfections. In order... more Ceramic rolling elements of hybrid bearings may initially include surface imperfections. In order to provide reliable operation of a bearing, the criticality of such imperfections under rolling contact fatigue is examined by defining them as Star features: intersecting semi-elliptical surface cracks. Parametric study is conducted using Finite Element Method and discussed with help of previously published experimental observations. The effects of the Star feature morphology and configuration, contact pressure and crack face friction are investigated in terms of stress intensity factors. Possible crack propagation scenarios are explained in the present study.

Research paper thumbnail of Characterization and modelling of the degradation of silicon nitride balls with surface missing-material defects under lubricated rolling contact conditions

Wear, 2018

Hybrid bearings in which ceramic rolling elements are used in combination with hardened steel rin... more Hybrid bearings in which ceramic rolling elements are used in combination with hardened steel rings outperform the conventional full-steel bearings in some demanding applications where high speed, high temperature, electric current, and thin-film or medium lubrication are involved. Despite the continued effort and progress made to improve the toughness, ceramics are regarded as brittle solids that can suffer in general from lack of damage tolerance in the form of sensitivity to pre-existing features that are seen as being potentially harmful. Under specific conditions, these imperfections may become critical for the reliability of hybrid bearings. This paper reports on a study of the degradation of silicon nitride ceramic balls, caused by surface missingmaterial (MM) defects under lubricated rolling contact conditions. Rolling contact fatigue test is conducted on the ceramic balls containing artificial defects of different configuration and sizes. Numerical simulation by means of finite element analysis indicates that the lubricant entrapped inside the MM cavity will be pressurized under rolling contact. The hydraulic pressure of the entrapped lubricant can result in significant tensile stress at the corner of the cavity that may cause crack initiation, initial crack propagation, and eventual spalling of the ball surface. Such a degradation mechanism is confirmed by the characteristics of the fatigue damage observed from the tested balls. Based on the understanding of the failure mechanism, a model based on the nonlocal approach to crack initiation at a V-notch is developed to describe the damage tolerance of the silicon nitride balls with the MM defects of specific geometry with respect to the rolling contact load. The prediction of the tolerance limits agrees well with the endurance limits of the silicon nitride balls tested under lubricated rolling contact conditions. This research has contributed to a fundamental understanding on what type and size of the MM defects can be tolerated in hybrid bearings in relation to used application running conditions.

Research paper thumbnail of Finite elements based approaches for the modelling of radial crack formation upon Vickers indentation in silicon nitride ceramics

Journal of the European Ceramic Society, 2019

By having superior properties silicon nitride ceramics can be considered as the state-of-the-art ... more By having superior properties silicon nitride ceramics can be considered as the state-of-the-art material in the bearing industry. Vickers indentation of this material is typically accompanied by formation of cracks visible on surface. Two Finite Elements models are developed in the current work: the first model is based on fracture mechanics and the second on cleavage stress criterion. Plastic behavior of silicon nitride is included in the modeling, and since little is known on the plasticity of this material, the Drucker-Prager model (used for nonmetallic materials) along with the classical J 2-plasticity are explored. The results of the fracture mechanics based model correlate well with experimental results in terms of surface crack length. The numerical results in terms of the morphology of the indented zone (including cracks and plastic zone) are provided by the stress criterion based model, and these results correlate well too, with the experimental data.

Research paper thumbnail of In-situ observation of crack propagation in silicon nitride ceramics

Procedia Structural Integrity, 2017

During their operation, modern aircraft engine components are subjected to increasingly demanding... more During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data.

Research paper thumbnail of Observation of subsurface rolling contact fatigue cracks in silicon nitride and comparison of their location to Hertzian contact subsurface stresses

International Journal of Fatigue, 2017

From lubricated rolling contact tests on silicon nitride rolling elements, genuine subsurface fat... more From lubricated rolling contact tests on silicon nitride rolling elements, genuine subsurface fatigue process from the Si3N4 microstructure was demonstrated and visualized for the first time by testing two different microstructure quality levels. Subsurface fatigue cracks initiating at microstructure features were found to be associated with local orthogonal shear stresses from the Hertzian stress field. All fatigue cracks displayed evidence of Mode II and III crack type propagation with an angle orientation that conformed to the shear stress direction.

Research paper thumbnail of Cavitation erosion in silicon nitride: Experimental investigations on the mechanism of material degradation

Tribology International, 2010

... B Karunamurthy a * , M Hadfield a , C Vieillard b , G Morales b . a Sustainable Design Resear... more ... B Karunamurthy a * , M Hadfield a , C Vieillard b , G Morales b . a Sustainable Design Research Centre, School of Design, Engineering and Computing ... [5] Scott D, Blackwell J, et al., 1971, Silicon nitride as a rolling bearing material a preliminary assessment, Wear, Vol 17(1) 73 ...

Research paper thumbnail of Large ceramic component and method of manufacture

Research paper thumbnail of Bearing and method of inhibiting crack propagation in a bearing component

Research paper thumbnail of Method for Manufacturing Ceramic Components

Research paper thumbnail of Bearing with light weight metal and ceramic material