ISSN Number

ISSN: 2147-9690

Turkish Journal of Engineering, Sciences and Technology

2015 Volume 3 Issue 2

 

Effect Of Slip Velocity And Roughness On The Jenkins Model Based Ferrofluid Lubrication Of A Curved Rough Annular Squeeze Film

Jimit R. Patela and Gunamani Deheri a

a Department of Mathematics, Sardar Patel University,Vallabh Vidyanagar, Anand, Gujarat India-388 120.

Abstract

This paper aims to evaluate the combined effect of slip velocity and roughness on the performance of a Jenkins model based ferrofluid squeeze film in curved annular plates. The model of Beavers and Joseph’s slip model has been considered to analyse the effect of slip velocity. Christensen and Tonder’s stochastic averaging method has been resorted to for studying the effect of surface roughness. The pressure distribution is obtained by solving the associated stochastically averaged Reynolds type equation with appropriate boundary conditions, leading to the calculation of load carrying capacity. The graphical representations suggest that the transverse surface roughness adversely affects the bearing performance. However, Jenkins model based ferrofluid lubrication offers some scopes in lowering this adverse effect when the slip parameter is kept at minimum. Of course, a suitable choice of curvature parameters adds to this positive effect in the case of negatively skewed roughness.  Besides, it is revealed that this type of bearing system supports certain amount of load, even when there is no flow, contrary to the case of conventional lubricant based bearing system.

Keywords: Annular plates, Magnetic fluid, Roughness, Jenkins model, Slip velocity.

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Curved Pivoted Porous Slider Bearings Lubricated With Micropolar Fluids

Siddangouda Aa , N. B. Naduvinamanib and Mahaveer D. Patilc

a Department of Mathematics, Appa Institute of Engineering & Technology, Gulbarga-585103, INDIA

b Department of Mathematics, Gulbarga University, Gulbarga-585106, INDIA

c Department of Mathematics, GPP Arts, Commerce & VVS Science College, Sindgi-586128, INDIA

Abstract

In this paper, the performance of the curved pivoted porous slider bearings is studied. The general modified Reynolds-type equation is derived on the basis of micro continuum theory. Microscopic effects generated by micromotions of particles in suspension in a viscous fluid drastically change the character of the flow between the solid walls. The closed form of expressions for the mean film pressure and load carrying capacity, frictional force is obtained. Numerical computations show that the performance of the slider bearings is prepared by the uses of lubricants with additives (micropolar fluids) as compared to the lubricants. Further it is observed that the micropolarity parameters  and increase the pressure, load carrying capacity, frictional force, coefficient of friction and centre of pressure. The effect of porous parameters causes the reduction of pressure and load carrying capacity.

Key words: Pivoted slider bearing, micropolar fluids, porous.

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An Evaluation Of Swell Rate Characteristics Of Orange Peel Particulate Green Composite Material Using Dimensional Analysis

Sunday Ayoola Okea

a Department of Mechanical Engineering, University of Lagos, Lagos, Nigeria

Abstract

This paper is motivated from the need to determine the expansive rate of orange peel particulates (OPP) in water. It is expected that findings obtained in this work would be helpful in a comparative analysis of the swell of OPP in other solvents and matrices when used in the composite fabrication process. Free swell experiments were set up according to Holtz and Gibbs model. Parametric quantities of the process were observed by taking readings on a daily basis from the time of the last experimental setup. A predictive model for the swell rate was developed by using the dimensional variables of the quantities to obtain a functional relationship that is dimensionless. It was observed that the 0.212 mm particle size has the highest mean swell rate of 2.96c m3/s. This was followed closely by the 0.600 mm size sample with an average swell rate of 2.58 cm3/s. The 0.300 and 0.425 mm samples had average swell rates of 1.16 and 1.35 cm3/s, respectively. According to the swell rate model, the influences of the increase in heights and masses were found to be more significant on the swell rate than the swollen density of the OPP.

Keywords: Composites reinforcement, water absorption, orange peels, particulates, green composites

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A study on the effects of tool material on the output parameters in Electrical Discharge Machining (EDM)

Hadi Eivazi Bagheria, Ali Hashemvandb

a Department of Mechanical Engineering, Babol University of Technology, Babol, Iran

b Department of Engineering, Islamic Azad University, Arak Branch, Arak, Iran

Abstract

In this paper the effect of tool material (copper, graphite and brass) along with other input parameters (machining gap and duty cycle) on output parameters of electrical discharge machining (material removal rate, tool wear ratio and surface roughness) in machining of AISI D6 tool steel has been studied. Based on this research results, the most material removal rate from the workpiece has been obtained by using graphite tool and the least amount of electrode wear ratio has been obtained by using copper tool. Also the results revealed that the least amount of workpiece surface roughness is obtained by brass tool. When using copper and graphite tools, which increase machining gap, material removal rate and surface roughness first increase then decrease. But when using brass tool, which increase machining gap, material removal ratio and surface roughness increase. The results show that, when using copper and graphite tools, which increase duty cycle, material removal rate and surface roughness first increase then decrease, but the tool wear ratio has a falling trend.

Keywords:EDM, AISI D6, Tool Material, MRR, TWR, Ra

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Determination Of Temperature Distribution For Porous Fin With Temperature-Dependent Heat Generation By Homotopy Analysis Method

H. A. Hoshyara, D. D. Ganjia, M. Abbasi a

a Department of Mechanical Engineering, Sari Branch, Islamic Azad University, Sari, Iran

Abstract

In this study, highly accurate analytical methods, Homotopy Analysis Method (HAM), is applied for predicting the temperature distribution in a porous fin with temperature dependent internal heat generation. The heat transfer through porous media is simulated using passage velocity from the Darcy’s model. It has been attempted to show the capabilities and wide-range applications of the Homotopy Analysis Method in comparison with a type of numerical analysis as Boundary Value Problem (BVP) in solving this problem.  The results show that the HAM is an attractive method in solving this problem.

Keywords: Homotopy Analysis Method, Porous fin, Temperature-dependent heat generation

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Bearing Fault Detection Techniques:A Review

Nabhan, A.a, Nouby, M.b, Sami, A. M.a, Mousa, M.O.a

aProduction and Design Dept., Faculty of Engineering, Minia University, El-Minia – 61111, Egypt

bMechanical Engineering Dept., Faculty of Engineering, South Valley University, Qena-83521, Egypt

Abstract

Detection of a rolling element fault is one of the most challenging tasks in bearing health condition monitoring, especially when the fault is at its initial stage.The defects in bearing unless detected in time may lead to malfunctioning of the machinery. The defects in the rolling element bearings may come up mainly due to the following reasons; improper design of the bearing or improper manufacturing or mounting, misalignment of bearing races, unequal diameter of rolling elements, improper lubrication, overloading, fatigue and uneven wear. This paper presents a detailed of the different detection techniquesused for measuring rolling bearing defects. From in depth study, four different methods for detection and diagnosis of bearing defects; they may be broadly classified as vibration measurements, acoustic measurements, temperature measurements and wear debris analysishave been identified. It is observed that the vibration analysis is most commonly accepted technique due to its ease of application.

Keywords: Bearing Defects,Vibration Measurements, Acoustic Measurements, Temperature       Measurements, Wear Debris Analysis.

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Analytical-Numerical And Numerical Linearization Of A Mini UAV Nonlinear Dynamic Model

Rahman Mohammadi Farhadia, Vyacheslav Ivanovich Kortunovb and Ali Mohammadic

a National Aerospace University named after N. Zhukovsky (KhAI), Kharkov, Ukraine

b National Aerospace University named after N. Zhukovsky (KhAI), Kharkov, Ukraine

c Malek-Ashtar University of Technology, Tehran, Iran

Abstract

Due to the high nonlinearities, time varying and uncertainties of the mini UAV dynamics, a lot of classical and advanced control techniques have been used in autopilot systems to guarantee a smooth desirable navigation trajectory. Reliable and accurate linearized dynamic model for such complicated nonlinear dynamic model is required for classical and robust control system design. In this paper nonlinear mathematical dynamic model for an Unmanned Aerial Vehicle (UAV) developed at low velocities in the presence of wind and then its linearized model derived using numerical and analytical-numerical methods. These linearized dynamic models and nonlinear one simulated andcompared with each other. It is shown that analytical-numerical and numerical linear models with nonlinear dynamic model confirm each other adequately. It must be mentioned that analytical-numerical linear model more accurate and closer to nonlinear model than numerical linear model, because of errors in calculating numerical linear model due to hard nonlinearities. Achieved linear models can be used for control system design purposes. Worst-case linear model obtained for aerodynamic coefficients uncertainties. It means that these linearized models can be used for obtaining required accurate nominal linear models and uncertainties to design robust control system.

Keywords: UAV, nonlinear and linear dynamic model, analytical and numerical linearization, nominal model, control system design, aerodynamic coefficient uncertainty.

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