Showing papers by "Prasanta Sahoo published in 2012"

Wear Behaviour of Al-SiCp Metal Matrix Composites and Optimization Using Taguchi Method and Grey Relational Analysis

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.

Influence of Process Parameters on Microhardness of Electroless Ni-B Coatings:

Abstract: Electroless Ni-B coatings have found large applications due to their high hardness and wear resistance. The present paper tries to investigate the influence of coating process parameters on the microhardness of electroless Ni-B coating with the help of Taguchi analysis. Four parameters, namely, bath temperature, concentration of reducing agent, concentration of nickel source, and annealing temperature, are considered and fitted into an L27 orthogonal array to find out the optimized condition for improved hardness of the coating. The optimized condition is found to yield about 19% improvement in hardness of the coating compared to the initial condition. The significance of the process parameters and their interactions on the hardness of Ni-B coating is studied with the help of analysis of variance, which revealed that annealing temperature and concentration of reducing agent have significant influence over the hardness characteristics of electroless Ni-B coating. The compositional, microstructural, and pha...

ANN modelling of fractal dimension in machining

Abstract: This chapter deals with fractal dimension modelling in machining operations. The study considers the fractal dimension to describe surface roughness. Four different machining operations, including CNC end milling, CNC turning, cylindrical grinding and EDM are carried out on mild steel (AISI 1040) work-pieces. The surface roughness data are used to develop models for predicting fractal dimension using artificial neural network (ANN). From the results of all machining operations, it is seen that developed models can predict fractal dimension very accurately.

Effect of Strain Hardening on Elastic-Plastic Contact of a Deformable Sphere against a Rigid Flat under Full Stick Contact Condition

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.

Optimization of Material Removal Rate in EDM Using Taguchi Method

Abstract: This paper presents an investigation on the effect and optimization of machining parameters on material removal rate (MRR) in electrical discharge machining (EDM) of EN31 tool steel. For the experiment, four process parameters viz. pulse on time, pulse off time, discharge current and voltage are considered. The settings of machining parameters are determined by using Taguchis orthogonal array (OA). L27 orthogonal array (OA) is considered for the study. The level of importance of the machining parameters on MRR is determined by analysis of variance (ANOVA) test. The optimum machining parameter combination is obtained by the analysis of signal-to-noise (S/N) ratio. The analysis shows that discharge current has the most significant effect on MRR followed by pulse off time and voltage. It is seen that with an increase in discharge current and pulse off time, MRR increases in the studied range. The methodology described here is expected to be highly beneficial to manufacturing industries.

Corrosion Study of Electroless Ni-P-W Coatings Using Electrochemical Impedance Spectroscopy

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 .

A numerical analysis of large amplitude beam vibration under different boundary conditions and excitation patterns

Abstract: Large amplitude forced vibration behavior of thin beams under harmonic excitation is studied, incorporating the effect of geometric nonlinearity. Large amplitude free vibration analysis of the same...

Potentiodynamic Polarization Behaviour of Electroless Ni-P-W Coatings

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.

Large Displacement of Crossbeam Structure through Energy Method

Abstract: This paper undertakes a geometric nonlinear large displacement static analysis of crossbeam structure. A crossbeam structure comprises two beams in contact with their longitudinal axes perpendicular to each other, used effectively in civil and mechanical engineering, marine and aerospace structures. The energy method forms the basis for the mathematical formulation and the governing set of equations are obtained using the principle of extremisation of the total energy of the system in its equilibrium state. To obtain the solution, an iterative procedure is developed based on the reaction force generated between the two beams of the system. The method is validated by experiment and simulation through ANSYS v11. Results are presented in terms of plots of reaction force and the displacement of the interaction point versus load in dimensional form and additionally, the deflected shapes of the crossbeam structure at static equilibrium condition, under a particular load, are provided. The static response of the system has been studied for variation of beam thickness, loading pattern and position of the supporting beam.

Optimization of Multiple Roughness Characteristics of Chemically Deposited Ni-P-W Coating Using Weighted Principal Component Analysis

Abstract: The present investigation deals with the chemical deposition of Ni-P-W coating on mild steel substrate and optimization of multiple surface roughness characteristics on the basis of different coating process parameters. Three coating parameters which are varied to have the optimum condition are concentration of nickel source, concentration of reducing agent, and concentration of tungsten source. Five different roughness parameters, namely, centre line average (Ra), root mean square roughness (Rq), skewness (𝑅sk), kurtosis (𝑅ku), and mean peak line spacing (𝑅sm) are considered. Weighted principal component analysis (WPCA) method is adopted to convert the multiple-response problem into a single performance index and Taguchi L27 orthogonal array is used. ANOVA is performed to find the significance of the each coating process parameters and their interactions. The EDX analysis, XRD analysis, and SEM are performed to study the composition and structural aspects.

Dynamic Analysis of Rotating Annular Disk of Variable Thickness under Uniform Axial Pressure

Abstract: The large-amplitude free vibration analysis of a rotating annular disk of exponentially varying thickness, subjected to uniform axial pressure, is presented. The entire formulation is energy-based and uses variational principles to derive the governing equations. The study is carried out up to the onset of yielding, which occurs due to the application of two types of external loadings, namely body force due to rotation and uniform axial pressure. The results are compared for three exponential disks having the same mass. The effects of the individual loadings and their combination on the free vibration dynamic behavior are presented.

Experimental investigation of static deflection and loaded natural frequencies of stiffened plates

Abstract: Experimental studies on static and dynamic behaviour of stiffened plates have been furnished in the present paper. These experiments are conducted on a set up simulating clamped boundary condition with provision for applying uniformly distributed transverse load. Experiments are carried out for three different types of plates, one unstiffened and two types of stiffened plates, which are uni-axially single stiffened and bi-axially cross stiffened plate. The aim is to determine the static deflection under transverse uniform pressure and the loaded natural frequencies of the stiffened plate specimens. The results for the static experiment are presented as load-deflection plot, whereas, frequency results are provided in terms of backbone curves in non-dimensional plane.