The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Narendra B Dahotre - One of the best experts on this subject based on the ideXlab platform.
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Laser Machining of Structural Ceramics: An Integrated Experimental and Numerical Approach for Surface Finish
2013Co-Authors: Hitesh D. Vora, Narendra B DahotreAbstract:Poster awarded first place in the 2013 UNT Graduate Exhibition in the Engineering category. This poster discusses laser machining of Structural Ceramics and an integrated experimental and numerical approach for surface finish.
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three dimensional laser machining of Structural Ceramics
Journal of Manufacturing Processes, 2010Co-Authors: Anoop N Samant, Narendra B DahotreAbstract:Abstract Three- dimensional laser machining of Structural Ceramics such as alumina (Al2O3), silicon nitride (Si3N4), silicon carbide (SiC) and magnesia (MgO) was carried out using a 1.06 μm wavelength pulsed Nd:YAG laser. The rate of machining predicted in terms of material removed per unit time (mg/s) increased with an increase in heating rate (K/s). A thermal model based on temperature dependent absorptivity and thermophysical properties, in addition to conduction, convection and radiation based heat transfer, was developed to predict material removal rate. Predicted values were compared with actual measurements made from machined cavities. Such a study would enable advance predictions of the laser processing conditions required to machine cavities of desired dimensions.
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Physical Effects of Multipass Two‐Dimensional Laser Machining of Structural Ceramics
Advanced Engineering Materials, 2009Co-Authors: Anoop N Samant, Narendra B DahotreAbstract:Effect of multiple laser passes on cavities machined in Structural Ceramics is presented. Multiple laser passes machined cavities with reduced thermal stresses and cracks. Thermal model based on temperature dependent absorptivity and thermophysical properties along with defocusing of laser beam, multiple track induced preheating effect, and heat transfer was developed to incorporate effect of multiple passes on machined cavity. Predicted and experimentally measured values of physical attributes showed decent match.
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differences in physical phenomena governing laser machining of Structural Ceramics
Ceramics International, 2009Co-Authors: Anoop N Samant, Narendra B DahotreAbstract:Several Structural Ceramics such as alumina, silicon nitride, silicon carbide and magnesia were machined using a pulsed Nd:YAG laser. Laser processing conditions and temperature dependent thermo-physical properties govern the physical phenomena that machine these Ceramics. Melting, dissociation and evaporation are some of the vital mechanisms associated with material removal. Discrimination and incorporation of these physical processes into a hydrodynamic machining model to predict different machining parameters was conducted. The model provides an outstanding tool for advance prediction of thermal energy and time required for machining desired depth of material.
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laser machining of Structural Ceramics a review
Journal of The European Ceramic Society, 2009Co-Authors: Anoop N Samant, Narendra B DahotreAbstract:Outstanding mechanical and physical properties like high thermal resistance, high hardness and chemical stability have encouraged use of Structural Ceramics in several applications. The brittle and hard nature of these Ceramics makes them difficult to machine using conventional techniques and damage caused to the surface while machining affects efficiency of components. Laser machining has recently emerged as a potential technique for attaining high material removal rates. This review paper aims at presenting the state of the art in the field of laser machining of Structural Ceramics and emphasizes on experimental and computational approaches in understanding physical nature of the complex phenomena.
Anoop N Samant - One of the best experts on this subject based on the ideXlab platform.
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three dimensional laser machining of Structural Ceramics
Journal of Manufacturing Processes, 2010Co-Authors: Anoop N Samant, Narendra B DahotreAbstract:Abstract Three- dimensional laser machining of Structural Ceramics such as alumina (Al2O3), silicon nitride (Si3N4), silicon carbide (SiC) and magnesia (MgO) was carried out using a 1.06 μm wavelength pulsed Nd:YAG laser. The rate of machining predicted in terms of material removed per unit time (mg/s) increased with an increase in heating rate (K/s). A thermal model based on temperature dependent absorptivity and thermophysical properties, in addition to conduction, convection and radiation based heat transfer, was developed to predict material removal rate. Predicted values were compared with actual measurements made from machined cavities. Such a study would enable advance predictions of the laser processing conditions required to machine cavities of desired dimensions.
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Physical Effects of Multipass Two‐Dimensional Laser Machining of Structural Ceramics
Advanced Engineering Materials, 2009Co-Authors: Anoop N Samant, Narendra B DahotreAbstract:Effect of multiple laser passes on cavities machined in Structural Ceramics is presented. Multiple laser passes machined cavities with reduced thermal stresses and cracks. Thermal model based on temperature dependent absorptivity and thermophysical properties along with defocusing of laser beam, multiple track induced preheating effect, and heat transfer was developed to incorporate effect of multiple passes on machined cavity. Predicted and experimentally measured values of physical attributes showed decent match.
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differences in physical phenomena governing laser machining of Structural Ceramics
Ceramics International, 2009Co-Authors: Anoop N Samant, Narendra B DahotreAbstract:Several Structural Ceramics such as alumina, silicon nitride, silicon carbide and magnesia were machined using a pulsed Nd:YAG laser. Laser processing conditions and temperature dependent thermo-physical properties govern the physical phenomena that machine these Ceramics. Melting, dissociation and evaporation are some of the vital mechanisms associated with material removal. Discrimination and incorporation of these physical processes into a hydrodynamic machining model to predict different machining parameters was conducted. The model provides an outstanding tool for advance prediction of thermal energy and time required for machining desired depth of material.
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laser machining of Structural Ceramics a review
Journal of The European Ceramic Society, 2009Co-Authors: Anoop N Samant, Narendra B DahotreAbstract:Outstanding mechanical and physical properties like high thermal resistance, high hardness and chemical stability have encouraged use of Structural Ceramics in several applications. The brittle and hard nature of these Ceramics makes them difficult to machine using conventional techniques and damage caused to the surface while machining affects efficiency of components. Laser machining has recently emerged as a potential technique for attaining high material removal rates. This review paper aims at presenting the state of the art in the field of laser machining of Structural Ceramics and emphasizes on experimental and computational approaches in understanding physical nature of the complex phenomena.
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Laser machining of Structural Ceramics—A review
Journal of The European Ceramic Society, 2009Co-Authors: Anoop N Samant, Narendra B DahotreAbstract:Outstanding mechanical and physical properties like high thermal resistance, high hardness and chemical stability have encouraged use of Structural Ceramics in several applications. The brittle and hard nature of these Ceramics makes them difficult to machine using conventional techniques and damage caused to the surface while machining affects efficiency of components. Laser machining has recently emerged as a potential technique for attaining high material removal rates. This review paper aims at presenting the state of the art in the field of laser machining of Structural Ceramics and emphasizes on experimental and computational approaches in understanding physical nature of the complex phenomena.
Xiaoyue Hu - One of the best experts on this subject based on the ideXlab platform.
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laser drilling of Structural Ceramics a review
Journal of The European Ceramic Society, 2017Co-Authors: Hongjian Wang, Chengyong Wang, Lijuan Zheng, Xiaoyue HuAbstract:Abstract Structural Ceramics are becoming widely popular in numerous fields because of high mechanical and physical properties. It is of great difficulty for conventional techniques to machine brittle and hard materials. As one of nontraditional machining methods, laser beam machining has emerged as an effective technique for drilling of Ceramics. This paper reviews the research work on laser drilling of Structural Ceramics from its different pulse width. Lasers have been discussed to understand effects of critical experimental parameters on the quality characteristics and physical mechanisms involved in drilling Ceramics. In addition, it is held that heat and liquid-assisted laser processing serves as a useful method to improve processing quality. Computational approaches of ANSYS and COMSOL are used to predict laser input parameters’ effects on quality of hole and describe the physical phenomena during processing. Comments on laser drilling of Ceramics developments and future directions are provided at the end.
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Laser drilling of Structural Ceramics—A review
Journal of The European Ceramic Society, 2017Co-Authors: Hongjian Wang, Chengyong Wang, Lijuan Zheng, Xiaoyue HuAbstract:Abstract Structural Ceramics are becoming widely popular in numerous fields because of high mechanical and physical properties. It is of great difficulty for conventional techniques to machine brittle and hard materials. As one of nontraditional machining methods, laser beam machining has emerged as an effective technique for drilling of Ceramics. This paper reviews the research work on laser drilling of Structural Ceramics from its different pulse width. Lasers have been discussed to understand effects of critical experimental parameters on the quality characteristics and physical mechanisms involved in drilling Ceramics. In addition, it is held that heat and liquid-assisted laser processing serves as a useful method to improve processing quality. Computational approaches of ANSYS and COMSOL are used to predict laser input parameters’ effects on quality of hole and describe the physical phenomena during processing. Comments on laser drilling of Ceramics developments and future directions are provided at the end.
I-wei Chen - One of the best experts on this subject based on the ideXlab platform.
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Fracture Mechanics of Fatigue of Structural Ceramics
Fracture Mechanics of Ceramics, 1996Co-Authors: I-wei Chen, David JacobsAbstract:Stable crack growth under cyclic loading has been observed in many Structural Ceramics which exhibit a rising toughness (R-curve) behavior.1-7 Although the growth is sometimes enhanced by the environmental factors, it can also proceed in vacuum where the environmental assistance is absent.6 This phenomenon has been extensively documented in recent years so that it is now possible to give a fairly general description of its mechanisms and kinetics. The purpose of this article is to incorporate the main body of the phenomenology into a micromechanical framework, within which the current understanding of the R-curve behavior and fatigue is fully reconciled.
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High Temperature Fatigue of Structural Ceramics.
1995Co-Authors: I-wei ChenAbstract:Abstract : The objective of the research effort was to establish a fundamental understanding of high temperature fatigue in Structural Ceramics. Two additional closely related areas, environmental effect on fatigue and temperature dependence on strength and toughness, were also targeted where basic understanding needed to be acquired. We were successful in establishing a comprehensive framework as the basis for understanding fatigue and fracture over a broad range of temperatures, static/cyclic loading conditions, and environmental conditions. The premises of that framework were: (1) Fatigue at low temperature is a process of mechanical balance in which resistance to crack advance is due to increased shielding whereas the impetus for crack advance is due to wear-caused degradation of crack wake shielding. (2) Fatigue at high temperature is a process of slow (creep) crack growth. Cyclic loading lowers the friction of grain boundary. The difference in crack growth rate in static and cyclic loadings can be rationalized by the different evolutions of crack-tip stress intensity factor under different grain boundary frictions. (3) Toughness in monolithic Ceramics is due to grain pullout. jg p.1
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Mechanistic Studies of Superplasticity of Structural Ceramics
1992Co-Authors: I-wei ChenAbstract:Abstract : A comprehensive methodology for developing superplastic Ceramics, evaluating superplastic formability, and understanding microStructural evolution and flow mechanisms during large deformation has been developed in the present project. A summary of these accomplishments, which focuses on two important classes of Structural Ceramics, zirconia and silicon nitride, is provided here in the form of nine published journal papers, conference contributions and general reviews. Ceramics, Superplasticity, Forming, Zirconia, Silicon Nitride
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development of superplastic Structural Ceramics
Journal of the American Ceramic Society, 1990Co-Authors: I-wei ChenAbstract:Superplastic Structural Ceramics (Y-TZP, A1203, Si3N4, and their composites) that can withstand biaxial stretching to large strains have been developed recently. MicroStructural design of these Ceramics first requires an ultrafine grain size that is stable against coarsening during sintering and deformation. A low sintering temperature is a necessary, but not a sufficient, condition for achieving the required microstructure. In many cases, the selection of an appropriate phase, such as tetragonal phase in zirconia or a phase in silicon nitride, which is resistant to grain growth, is crucial. The use of sintering aids and grain-growth inhibitors, particularly those that segregate to the grain boundaries, can be beneficial. Second-phase particles are especially effective in suppressing static and dynamic grain growth. Another major concern is to maintain an adequate grain-boundary cohesive strength, relative to the flow stress, to mitigate cavitation or grain-boundary cracking during large strain deformation. Existing evidence suggests that a lower grainboundary energy is instrumental in achieving this objective. The selection of an appropriate phase and the tailoring of the grain boundary or liquid-phase composition can sometimes drastically alter the cavitation resistance. Related observations on forming methods, forming characteristics, and sheet formability are also reviewed. The basic deformation characteristics are similar to diffusional creep and are dominated by R. E. Newnham-contributing editor
Hongjian Wang - One of the best experts on this subject based on the ideXlab platform.
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laser drilling of Structural Ceramics a review
Journal of The European Ceramic Society, 2017Co-Authors: Hongjian Wang, Chengyong Wang, Lijuan Zheng, Xiaoyue HuAbstract:Abstract Structural Ceramics are becoming widely popular in numerous fields because of high mechanical and physical properties. It is of great difficulty for conventional techniques to machine brittle and hard materials. As one of nontraditional machining methods, laser beam machining has emerged as an effective technique for drilling of Ceramics. This paper reviews the research work on laser drilling of Structural Ceramics from its different pulse width. Lasers have been discussed to understand effects of critical experimental parameters on the quality characteristics and physical mechanisms involved in drilling Ceramics. In addition, it is held that heat and liquid-assisted laser processing serves as a useful method to improve processing quality. Computational approaches of ANSYS and COMSOL are used to predict laser input parameters’ effects on quality of hole and describe the physical phenomena during processing. Comments on laser drilling of Ceramics developments and future directions are provided at the end.
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Laser drilling of Structural Ceramics—A review
Journal of The European Ceramic Society, 2017Co-Authors: Hongjian Wang, Chengyong Wang, Lijuan Zheng, Xiaoyue HuAbstract:Abstract Structural Ceramics are becoming widely popular in numerous fields because of high mechanical and physical properties. It is of great difficulty for conventional techniques to machine brittle and hard materials. As one of nontraditional machining methods, laser beam machining has emerged as an effective technique for drilling of Ceramics. This paper reviews the research work on laser drilling of Structural Ceramics from its different pulse width. Lasers have been discussed to understand effects of critical experimental parameters on the quality characteristics and physical mechanisms involved in drilling Ceramics. In addition, it is held that heat and liquid-assisted laser processing serves as a useful method to improve processing quality. Computational approaches of ANSYS and COMSOL are used to predict laser input parameters’ effects on quality of hole and describe the physical phenomena during processing. Comments on laser drilling of Ceramics developments and future directions are provided at the end.
