This study is based on the examination of the morphology of the wear of the P35 metal carbide ins... more This study is based on the examination of the morphology of the wear of the P35 metal carbide inserts and the carbide inserts with simple coating lay down TiN. The analysis was carried out initially by an exploration of the plates by white light interferometric microscope to white light. A second examination of the plates is carried out by the scanning electronic microscope with sweeping. The interferometric examination enabled us to evaluate with a very high degree of accuracy the depth of wear in the substrate composing materials of cut. It also allowed us to evaluate the thickness of the layer of the coating. The examination on the SEM consists in investigating wear and studying its morphology and identifying the chemical composition of the substrate used for the manufacture of the plates. The obtained results will be used to describe the nature of wear and the mechanism of its formation. Keywords: Carbide inserts, Coatings chock, Wear, White light Interferometry, Milling.
Deux facteurs K et Kmax gouvernent principalement la propagation d’une fissure de fatigue dans n... more Deux facteurs K et Kmax gouvernent principalement la propagation d’une fissure de fatigue dans n’importe quel matériau. Ce concept de base a été utilisé dans le cas d’un chargement en fatigue en Traction-Traction et en Traction-Compression. Dans le présent travail nous s’intéressons au comportement en fatigue en compression-compression des biocéramiques utilisées pour la conception des prothèses ostéo-articulaires et de donner une réponse au manque de résistance à la fatigue, provoquant une rupture brutale de l’implant. Les prothèse totale sont sollicités en compression, la propagation des fissures se fait essentiellement par traction induite. Nous simulons les conditions de chargement sur éprouvettes entaillées du type CT par analogie aux travaux effectués par Ritchie et Dickson sur la céramique technique, afin d’étudier l’amorçage et la propagation des fissures de fatigue à partir d’une entaille mécanique dans des conditions proches des condition les plus sévères. Pour caractéris...
2007 2nd IEEE/IFIP International Workshop on Broadband Convergence Networks, 2007
The problem of terminal-pair reliability has been extensively studied for wired computer networks... more The problem of terminal-pair reliability has been extensively studied for wired computer networks, however comparatively less research has been done on the reliability of wireless networks. With mesh networks becoming a more attractive option than the traditional pointto-multipoint network design due to extended coverage and increased overall link quality, a method is needed to evaluate the added reliability obtained through the available path diversity in fixed wireless mesh networks. Methods are available to evaluate the reliability of wired networks, however they do not take into account the outage conditions found in a wireless environment such as multipath fading and interference. This paper combines the currently available reliability algorithms for wired networks along with methods to calculate the link and node outage in a fixed station IEEE 802.16 environment in order the simulate the reliability of a mesh subscriber station's connection to the base station. An example calculation is also provided.
In the machining of heat resistant super alloys used in aeronautical applications and classified ... more In the machining of heat resistant super alloys used in aeronautical applications and classified as difficult-to-machine materials, the consumption of cooling lubricant during the machining operations is very important. The associated costs of coolant acquisition, use, disposal and washing the machined components are significant, up to four times the cost of consumable tooling used in the cutting operations. To reduce the costs of production and to make the processes environmentally safe, the goal of the aeronautical manufacturers is to move toward dry cutting by eliminating or minimising cutting fluids. This goal can be achieved by using coated carbide tools at high cutting speeds. To achieve this goal, different coated tools and different cutting conditions were tested in dry conditions. The elementary orthogonal cutting process was chosen, the cutting and feed cutting forces components were measured and the cutting force ratio calculated. This ratio is shown to be as an interesting indicator of tool wear. The tool wear mechanisms tool were analysed by using white light interferometer and scanning electron microscopy coupled to an energy-dispersive X-ray spectroscopy EDS-system. The EDS was very useful to analyse the elements deposited on the cutting tool faces. The ability of the different coatings to increase the carbide tool performance were analysed, the main wear modes were depicted. An optimisation of the cutting conditions was finally proposed and the efficiency of the coatings was shown. The results coming from uncoated tools were compared with those obtained with coated tools under the same conditions of machining. At the end, a choice of coatings is proposed and an extension of this study to an industrial machining operation is presented for future developments. (A. Devillez). which produces engines for commercial and military aircraft and space engines. Due to their high temperature strength and high corrosion resistance, nickel alloys are used for these applications, Inconel 718 superalloy is one of them. In this paper, attention is pointed on machining this material well known as difficult-to-cut. During machining Inconel 718, the cutting tool often supports extreme thermal and mechanical loads close to the cutting edge leading to rapid tool wear. In addition, welding and adhesion of worked material onto the cutting tool frequently occur during machining causing severe notching as well as alteration of the tool rake face due to the consequent pull-out of coating and tool substrate. Coated carbide and ceramics tools are generally used for high speed machining Inconel 718. For the coated carbide tools, the right selection of the tungsten carbidecobalt alloy for the substrate, the associated coating materials, the coating procedure and the cutting conditions choice are the main problems .
This paper presents an investigation of spallation in impact-loaded glass. For this purpose, spal... more This paper presents an investigation of spallation in impact-loaded glass. For this purpose, spall tests on cylindrical specimens were performed for various impact velocities using a Hopkinson bar "HB". After each test, the specimen was rebuilt from restored fragments and the analysis of the fracture surface was performed by means of a scanning electron microscope. Fracture is found to propagate in a transversal way. In addition, numerical modeling allowed an appropriate prediction of the experimental stress level, time to fracture and fracture location. Based on microscopic observations of the fractured surface, a new fracture criterion has been proposed. It defines the damage variable as a function of the ratio between the initial surface and its evolution.
This article investigates the machinability of two Al/SiC particulate metal-matrix composites (MM... more This article investigates the machinability of two Al/SiC particulate metal-matrix composites (MMC) with 5 and 15% vol. SiC particles. Dry turning tests were performed with three different CVD diamond-coated tools. In a first series of experiments, various cutting conditions were tested and their effects on tool wear mechanisms were studied. For the second series, optimal cutting conditions were chosen and tool
In the machining of Inconel 718, nickel based heat resistant superalloy and classified difficult-... more In the machining of Inconel 718, nickel based heat resistant superalloy and classified difficult-to-cut material, the consumption of cooling lubricant is very important. To reduce the costs of production and to make the processes environmentally safe, the goal is to move toward dry cutting by eliminating cutting fluids. This goal can be achieved by using coated carbide tool and by increasing cutting speed.
The work here presented intends to study the influence of the shape of loading on the fatigue lif... more The work here presented intends to study the influence of the shape of loading on the fatigue life in case of multiaxial loading. The practical undergoing problem is the fatigue life of high speed railways wheels. They are here considered as loaded in tension (or compression) and in torsion.Several multiaxial fatigue life criteria exist, but the most of them use
Incorporation of Advanced High Strength Steels in structural parts of vehicles should save weight... more Incorporation of Advanced High Strength Steels in structural parts of vehicles should save weight and enable economy of fuel. A very efficient protection against corrosion is achieved by hot-dip galvanization, which consists in dipping the steel in a molten zinc bath at a temperature around 450°C. Degradation of the fatigue toughness of several steels after galvanization has been reported in
The evaluation of static properties and lifetime of a pipeline notched under the impact of sand w... more The evaluation of static properties and lifetime of a pipeline notched under the impact of sand with or without the presence of hydrogen has been performed. The material damage was made by electrolytic hydrogen and projecting corundum particles (aluminium oxide). It has been shown that sandblasting and hydrogen have little affect on the yield stress and ultimate strength. The material lifetime and elongation at fracture are clearly affected by hydrogen, which penetrates into the surface layers of the material and changes the local fracture mechanism. Despite the erosion of these layers, under the sand impacting, failure strain and lifetime are improved. The observation of failure mode shows that the deformation field, after sandblasting, is very important. The crack propagation and the failure seem to be intra granular. The cracks, in the pipeline API 5L X52 steel charged with hydrogen, propagate following the porosity path without any distinct direction. The absorbed hydrogen atoms placed inside the crystalline sites of steel cause the embrittlement of material so that a small effort is sufficient to create cleavage. Modified notch failure assessment diagram was used to evaluate the dangerousness of studied notch defect in different environments: air, hydrogen and sandblasting.
This study is based on the examination of the morphology of the wear of the P35 metal carbide ins... more This study is based on the examination of the morphology of the wear of the P35 metal carbide inserts and the carbide inserts with simple coating lay down TiN. The analysis was carried out initially by an exploration of the plates by white light interferometric microscope to white light. A second examination of the plates is carried out by the scanning electronic microscope with sweeping. The interferometric examination enabled us to evaluate with a very high degree of accuracy the depth of wear in the substrate composing materials of cut. It also allowed us to evaluate the thickness of the layer of the coating. The examination on the SEM consists in investigating wear and studying its morphology and identifying the chemical composition of the substrate used for the manufacture of the plates. The obtained results will be used to describe the nature of wear and the mechanism of its formation. Keywords: Carbide inserts, Coatings chock, Wear, White light Interferometry, Milling.
Deux facteurs K et Kmax gouvernent principalement la propagation d’une fissure de fatigue dans n... more Deux facteurs K et Kmax gouvernent principalement la propagation d’une fissure de fatigue dans n’importe quel matériau. Ce concept de base a été utilisé dans le cas d’un chargement en fatigue en Traction-Traction et en Traction-Compression. Dans le présent travail nous s’intéressons au comportement en fatigue en compression-compression des biocéramiques utilisées pour la conception des prothèses ostéo-articulaires et de donner une réponse au manque de résistance à la fatigue, provoquant une rupture brutale de l’implant. Les prothèse totale sont sollicités en compression, la propagation des fissures se fait essentiellement par traction induite. Nous simulons les conditions de chargement sur éprouvettes entaillées du type CT par analogie aux travaux effectués par Ritchie et Dickson sur la céramique technique, afin d’étudier l’amorçage et la propagation des fissures de fatigue à partir d’une entaille mécanique dans des conditions proches des condition les plus sévères. Pour caractéris...
2007 2nd IEEE/IFIP International Workshop on Broadband Convergence Networks, 2007
The problem of terminal-pair reliability has been extensively studied for wired computer networks... more The problem of terminal-pair reliability has been extensively studied for wired computer networks, however comparatively less research has been done on the reliability of wireless networks. With mesh networks becoming a more attractive option than the traditional pointto-multipoint network design due to extended coverage and increased overall link quality, a method is needed to evaluate the added reliability obtained through the available path diversity in fixed wireless mesh networks. Methods are available to evaluate the reliability of wired networks, however they do not take into account the outage conditions found in a wireless environment such as multipath fading and interference. This paper combines the currently available reliability algorithms for wired networks along with methods to calculate the link and node outage in a fixed station IEEE 802.16 environment in order the simulate the reliability of a mesh subscriber station's connection to the base station. An example calculation is also provided.
In the machining of heat resistant super alloys used in aeronautical applications and classified ... more In the machining of heat resistant super alloys used in aeronautical applications and classified as difficult-to-machine materials, the consumption of cooling lubricant during the machining operations is very important. The associated costs of coolant acquisition, use, disposal and washing the machined components are significant, up to four times the cost of consumable tooling used in the cutting operations. To reduce the costs of production and to make the processes environmentally safe, the goal of the aeronautical manufacturers is to move toward dry cutting by eliminating or minimising cutting fluids. This goal can be achieved by using coated carbide tools at high cutting speeds. To achieve this goal, different coated tools and different cutting conditions were tested in dry conditions. The elementary orthogonal cutting process was chosen, the cutting and feed cutting forces components were measured and the cutting force ratio calculated. This ratio is shown to be as an interesting indicator of tool wear. The tool wear mechanisms tool were analysed by using white light interferometer and scanning electron microscopy coupled to an energy-dispersive X-ray spectroscopy EDS-system. The EDS was very useful to analyse the elements deposited on the cutting tool faces. The ability of the different coatings to increase the carbide tool performance were analysed, the main wear modes were depicted. An optimisation of the cutting conditions was finally proposed and the efficiency of the coatings was shown. The results coming from uncoated tools were compared with those obtained with coated tools under the same conditions of machining. At the end, a choice of coatings is proposed and an extension of this study to an industrial machining operation is presented for future developments. (A. Devillez). which produces engines for commercial and military aircraft and space engines. Due to their high temperature strength and high corrosion resistance, nickel alloys are used for these applications, Inconel 718 superalloy is one of them. In this paper, attention is pointed on machining this material well known as difficult-to-cut. During machining Inconel 718, the cutting tool often supports extreme thermal and mechanical loads close to the cutting edge leading to rapid tool wear. In addition, welding and adhesion of worked material onto the cutting tool frequently occur during machining causing severe notching as well as alteration of the tool rake face due to the consequent pull-out of coating and tool substrate. Coated carbide and ceramics tools are generally used for high speed machining Inconel 718. For the coated carbide tools, the right selection of the tungsten carbidecobalt alloy for the substrate, the associated coating materials, the coating procedure and the cutting conditions choice are the main problems .
This paper presents an investigation of spallation in impact-loaded glass. For this purpose, spal... more This paper presents an investigation of spallation in impact-loaded glass. For this purpose, spall tests on cylindrical specimens were performed for various impact velocities using a Hopkinson bar "HB". After each test, the specimen was rebuilt from restored fragments and the analysis of the fracture surface was performed by means of a scanning electron microscope. Fracture is found to propagate in a transversal way. In addition, numerical modeling allowed an appropriate prediction of the experimental stress level, time to fracture and fracture location. Based on microscopic observations of the fractured surface, a new fracture criterion has been proposed. It defines the damage variable as a function of the ratio between the initial surface and its evolution.
This article investigates the machinability of two Al/SiC particulate metal-matrix composites (MM... more This article investigates the machinability of two Al/SiC particulate metal-matrix composites (MMC) with 5 and 15% vol. SiC particles. Dry turning tests were performed with three different CVD diamond-coated tools. In a first series of experiments, various cutting conditions were tested and their effects on tool wear mechanisms were studied. For the second series, optimal cutting conditions were chosen and tool
In the machining of Inconel 718, nickel based heat resistant superalloy and classified difficult-... more In the machining of Inconel 718, nickel based heat resistant superalloy and classified difficult-to-cut material, the consumption of cooling lubricant is very important. To reduce the costs of production and to make the processes environmentally safe, the goal is to move toward dry cutting by eliminating cutting fluids. This goal can be achieved by using coated carbide tool and by increasing cutting speed.
The work here presented intends to study the influence of the shape of loading on the fatigue lif... more The work here presented intends to study the influence of the shape of loading on the fatigue life in case of multiaxial loading. The practical undergoing problem is the fatigue life of high speed railways wheels. They are here considered as loaded in tension (or compression) and in torsion.Several multiaxial fatigue life criteria exist, but the most of them use
Incorporation of Advanced High Strength Steels in structural parts of vehicles should save weight... more Incorporation of Advanced High Strength Steels in structural parts of vehicles should save weight and enable economy of fuel. A very efficient protection against corrosion is achieved by hot-dip galvanization, which consists in dipping the steel in a molten zinc bath at a temperature around 450°C. Degradation of the fatigue toughness of several steels after galvanization has been reported in
The evaluation of static properties and lifetime of a pipeline notched under the impact of sand w... more The evaluation of static properties and lifetime of a pipeline notched under the impact of sand with or without the presence of hydrogen has been performed. The material damage was made by electrolytic hydrogen and projecting corundum particles (aluminium oxide). It has been shown that sandblasting and hydrogen have little affect on the yield stress and ultimate strength. The material lifetime and elongation at fracture are clearly affected by hydrogen, which penetrates into the surface layers of the material and changes the local fracture mechanism. Despite the erosion of these layers, under the sand impacting, failure strain and lifetime are improved. The observation of failure mode shows that the deformation field, after sandblasting, is very important. The crack propagation and the failure seem to be intra granular. The cracks, in the pipeline API 5L X52 steel charged with hydrogen, propagate following the porosity path without any distinct direction. The absorbed hydrogen atoms placed inside the crystalline sites of steel cause the embrittlement of material so that a small effort is sufficient to create cleavage. Modified notch failure assessment diagram was used to evaluate the dangerousness of studied notch defect in different environments: air, hydrogen and sandblasting.
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Papers by S. Dominiak