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Search Results: 1 - 10 of 1027 matches for " Prasanta Sahoo "
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A Finite Element Study of Elastic-Plastic Hemispherical Contact Behavior against a Rigid Flat under Varying Modulus of Elasticity and Sphere Radius  [PDF]
Prasanta Sahoo, Biplab Chatterjee
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.24030
Abstract: The present study considers a finite element analysis of elastic-plastic axi-symmetric hemispherical contact for a frictionless deformable sphere pressed by a rigid flat. The material of the sphere is modeled as elastic perfectly plastic. Analysis is carried out to study the effect of varying modulus of elasticity and sphere radius in wide range of dimensionless interference until the inception of plasticity as well as in plastic range. Results are compared with previous elastic-plastic models. It is found that materials with Young’s modulus to yield strength (E/Y) ratio less than and greater than 300 show strikingly different contact phenomena. The dependency of E on dimensionless interference at which the plastic region fully covers the surface is observed. However with different radius, finite element study exhibits similar elastic-plastic phenomena.
Study of Potentiodynamic Polarization Behaviour of Electroless Ni-B Coatings and Optimization using Taguchi Method and Grey Relational Analysis  [PDF]
Suman Kalyan Das, Prasanta Sahoo
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.1014103
Abstract: Electroless nickel coatings are very popular for their corrosion resistant actions. The present article attempts to study the corrosion behaviour of electroless Ni-B coatings by varying the coating parameters viz. bath temperature, reducing agent concentration and nickel source concentration together with the annealing temperature. The electrochemical parameters viz., corrosion potential and corrosion current density are evaluated with the help of potentiodynamic polarization experimentation. Taguchi based Grey analysis is employed in order to optimize this multiple response problem and the optimal combination of parameters for maximum corrosion resistance for Ni-B coatings is presented. Moreover, analysis of variance reveals that bath temperature and concentration of nickel source have significant influence on the corrosion performance of the coating. The microstructure characterization of the coating is also conducted with the help of scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction analysis. The Ni-B coating in general exhibits a nodular structure and turns crystalline with heat treatment. The corroded surface exhibits cracks and black spots which imply the occurrence of localized corrosion.
Wear Behaviour of Al-SiCp Metal Matrix Composites and Optimization Using Taguchi Method and Grey Relational Analysis  [PDF]
Shouvik Ghosh, Prasanta Sahoo, Goutam Sutradhar
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2012, DOI: 10.4236/jmmce.2012.1111115
Abstract: Aluminium metal matrix composite is a relatively new material that has proved its position in automobile, aerospace and other engineering design applications due to its wear resistance and substantial hardness. Need for improved tribological performance has led to the design and selection of newer variants of the composite. The present investigation deals with the study of wear behaviour of Al-SiCp metal matrix composite for varying reinforcement content, applied load, sliding speed and time. Aluminium metal matrix composites reinforced with SiC particles are prepared by liquid metallurgy route using LM6 aluminium alloy and silicon carbide particles (size ~ 37 μm) by varying the weight fraction of SiC in the range of 5% - 10%. The material is synthesized by stir casting process in an electric melting furnace. The materials are then subjected to wear testing in a multitribotester using block on roller configuration. A plan of experiments based on L27 Taguchi orthogonal array is used to acquire the wear data in a controlled way. An analysis of variance is employed to investigate the influence of four controlling parameters, viz., SiC content, normal load, sliding speed and sliding time on dry sliding wear of the composites. It is observed that SiC content, sliding speed and normal load significantly affect the dry sliding wear. The optimal combination of the four controlling parameters is also obtained for minimum wear. The microstructure study of worn surfaces indicates nature of wear to be mostly abrasive.
Effect of Strain Hardening on Elastic-Plastic Contact of a Deformable Sphere against a Rigid Flat under Full Stick Contact Condition
Biplab Chatterjee,Prasanta Sahoo
Advances in Tribology , 2012, DOI: 10.1155/2012/472794
Abstract: The present study considers the effect of strain hardening on elastic-plastic contact of a deformable sphere with a rigid flat under full stick contact condition using commercial finite element software ANSYS. Different values of tangent modulus are considered to study the effect of strain hardening. It is found that under a full stick contact condition, strain hardening greatly influences the contact parameters. Comparison has also been made between perfect slip and full stick contact conditions. It is observed that the contact conditions have negligible effect on contact parameters. Studies on isotropic and kinematic hardening models reveal that the material with isotropic hardening has the higher load carrying capacity than that of kinematic hardening particularly for higher strain hardening. 1. Introduction Surface interactions are dependent on the contacting materials and the shape of the contacting surfaces. The shape of the surface of an engineering material is a function of both its production process and the nature of the parent material. When studied carefully on a very fine scale, all solid surfaces are found to be rough. So when two such surfaces are pressed together under loading, only the peaks or the asperities of the surface are in contact and the real area of contact is only a fraction of the apparent area of contact. In such conditions the pressure in those contact spots are high. Accurate calculation of contact area and contact load are of immense importance in the field of tribology and lead to an improved understanding of friction, wear, and thermal and electrical conductance between surfaces. However, it is a difficult task as rough surfaces consist of asperities having different radius and height. The problem is simplified when Hertz [1] provides the contact analysis of two elastic solids with geometries defined by quadratic surfaces. From then, the assumption of surfaces having asperities of spherical shape is adopted to simplify the contact problems. Greenwood and Williamson [2] used the Hertz theory and proposed an asperity-based elastic model where asperity heights follow a Gaussian distribution. Hertz assumed frictionless surfaces and his theory is restricted for perfectly elastic solids. Later on, researchers have attempted to investigate the effect of material properties beyond the Hertz restriction and the elastic plastic contact of a sphere with a flat became a fundamental problem in contact mechanics. The plastic model introduced by Abbot and Firestone [3], neglects volume conservation of the plastically deformed sphere.
Effect of Strain Hardening on Unloading of a Deformable Sphere Loaded against a Rigid Flat – A Finite Element Study
Biplab Chatterjee,Prasanta Sahoo
International Journal of Engineering and Technology , 2010,
Abstract: The present study considers an elastic-plastic contact analysis during loading-unloading of a deformable sphere with a rigid flat using finite element method. The effect of strain hardening on the contact behavior of a nonadhesive frictionless elastic-plastic contact is analyzed using commercial finite element software ANSYS. To study the strain hardening effect different values of tangentmodulus are considered by varying the hardening parameter. The range of hardening parameter is chosen in such a way that most of the practical materials belong in this range. The effect of strain hardening is explained through the results of simulations and compared with elastic perfectly plastic models as well as available loadingunloading models. Analysis has been carried out for deformations up to 200 times the critical interference. It is found that the contact parameters during loadingunloading are not of uniform nature within the range of hardening parameters used in this study. Increased strain hardening results in less residual strain and offer less resistance to full recovery of the original spherical shape. Multiple loading-unloading is also done for two extreme cases of hardening parameters to study the fluctuation of dimensionless interference during subsequent cycles. The contact parameters are found identical with first cycle of loading-unloading.
Corrosion Study of Electroless Ni-P-W Coatings Using Electrochemical Impedance Spectroscopy
Supriyo Roy,Prasanta Sahoo
Portugaliae Electrochimica Acta , 2012,
Abstract: The present study investigates the significance of different coating process parameters on the corrosion behaviour of electrolessly deposited Ni-P-W coatings on mild steel substrate. The process parameters considered are concentration of nickel source, concentration of reducing agent, concentration of tungsten source and annealing temperature. The corrosion characteristic is evaluated by electrochemical impedance spectroscopy technique. The responses considered are charge transfer resistance and double layer capacitance. The Taguchi technique coupled with grey analysis is employed to find out the optimum combination of the process parameters for better corrosion resistance. Analysis of variance (ANOVA) reveals the contribution of the process parameters on the corrosion property of Ni-P-W coating. Finally a validation test is performed to justify the experimental result. The microstructure of the surface is studied by scanning electron microscopy (SEM); energy dispersive x-ray analysis (EDX) reveals the chemical composition and the x-ray diffraction analysis (XRD) is used to identify the phase transformation behaviour of the coating.
Potentiodynamic Polarization Behaviour of Electroless Ni-P-W Coatings
Supriyo Roy,Prasanta Sahoo
ISRN Corrosion , 2012, DOI: 10.5402/2012/914867
Abstract:
Optimization of Multiple Roughness Characteristics of Chemically Deposited Ni-P-W Coating Using Weighted Principal Component Analysis
Supriyo Roy,Prasanta Sahoo
ISRN Mechanical Engineering , 2012, DOI: 10.5402/2012/495857
Abstract:
Optimization of Electroless Ni-P-W Coatings for Minimum Friction and Wear Using Grey-Taguchi Method
Supriyo Roy,Prasanta Sahoo
Journal of Coatings , 2013, DOI: 10.1155/2013/608140
Abstract: The present experimental investigation deals with the deposition of electroless Ni-P-W coating on mild steel substrate and optimization of tribological parameters for better tribological behaviour like minimization of wear depth and coefficient of friction. Three tribological test parameters, namely, load, speed, and time, are optimized for minimum friction and wear of the coating. Friction and wear tests are carried out in a multitribotester using block on roller configuration under dry conditions. Taguchi based grey relational analysis is employed for optimization of this multiple response problem using L27 orthogonal array. Analysis of variance shows that load, speed, time, and interaction between load and speed have significant influence on controlling the friction and wear behavior of Ni-P-W coating. It is observed that wear mechanism is mild adhesive in nature. The structural morphology, composition, and phase structure of the coating are studied with the help of scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction analysis (XRD), respectively. 1. Introduction Most of the engineering components undergo rubbing action due to which wear takes place on the surface of the components and become useless after a certain period. Life and performance of these engineering components can be extended by applying hard coatings over the surface of the components. The thickness of coatings ranged between 10 and 500?μm and their rates of deposition can provide the required product quality at relatively low capital and operating costs. Among the various metallic coating procedures based on aqueous solutions, most metals are electroplated since electroplating is technically straightforward and less expensive than electroless (autocatalytic) deposition. On the other hand, electroless deposition is of industrial importance mainly for copper, nickel, and some nickel based alloys. Industrial use of electroless deposition method continues to increase due to its good anticorrosion, antifriction, and wear protection properties. Electroless method has several advantages over electroplating technique, except for the life of the bath. The advantages include the quality of the deposit, namely, the physical and mechanical properties. In this process, a sharp edge receives the same thickness of deposit as a blind hole does and it offers extremely bright deposits, which are comparable with electroplated ones. The desirable properties can be varied by choosing different pH, temperature, and composition of the bath. Electroless nickel
Potentiodynamic Polarization Behaviour of Electroless Ni-P-W Coatings
Supriyo Roy,Prasanta Sahoo
ISRN Corrosion , 2012, DOI: 10.5402/2012/914867
Abstract: This paper deals with the synthesis of electroless Ni-P-W coatings on mild steel substrate followed by furnace-annealing process. Corrosion behaviors of the coatings after heat treatments at various annealing temperatures are evaluated by potentiodynamic polarization test using 3.5% sodium chloride solution. The electrochemical parameters, that is, corrosion potential and corrosion current density, are optimized for maximum corrosion resistance using Taguchi-based grey relational analysis, considering four coating parameters, namely, concentration of nickel, concentration of reducing agent, concentration of tungsten, and annealing temperature as main design factors. The optimum combination of these four design factors is obtained from the analysis. The analysis of variance reveals that the concentration of tungsten source and annealing temperature play the most important role on the corrosion performance of the coating. Effects of the operating parameters on microstructures, in terms of porosity formation, crystallization, phase transformation, grain growth, are investigated using SEM, EDX, and XRD techniques. 1. Introduction The performance and lifetime of engineering components can be enhanced by applying hard coating over the surface of the components, by allowing the mechanical properties of the substrate material to be maintained while protecting them against wear, friction, or corrosion. Basically the coating acts as a barrier to the substrate material by sealing it from the environment. Among the coating processes the electroless coating process is now widely accepted by the industries due to its simplicity and enhanced properties like improved friction, wear, and anticorrosive properties. The basic hypophosphite-reduced Ni-P and borohydride-reduced Ni-B coating has proved its supremacy in providing improved hardness, corrosion, and wear resistance [1–4]. The corrosion resistance of electroless Ni-P coating is excellent, moreover in some environments it is superior to that of pure nickel or chromium alloys due to the amorphous nature and passivity of the coating [5]. It is obvious that increasing of coating porosity decreases the corrosion resistance of the coating. The important factor that affects the coating porosity and ultimate resistance to corrosion attack is surface roughness which is influenced by mechanical preparation of the surface and electroless nickel-coating process procedure [6]. Recently, much attention is being paid towards composite electroless nickel plating. The properties of composite electroless nickel coatings are often
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