Indian Journal of

Engineering & Materials Sciences

 

VOLUME 8

NUMBER 3

JUNE 2001

 

CONTENTS

Engineering

Revisit to the stability of a uniform cantilever column subjected to Euler and Beck loads—Effect of realistic follower forces

 

123

  G Venkateswara Rao & Gajbir Singh

 

 

 

Effect of split injection on diesel engine pollutants using multi-zone model

129

  G Devaradjane

 

 

 

Measure of parallelism for in-parallel robotic structures

136

  A C Rao & Anne Jagadeesh

 

 

 

Effect of aspect ratio and curvature on characteristics of S-shaped diffusers

141

  Vinit Gupta, Rajneesh Devpura, S N Singh & V Seshadri

 

 

 

Determination of mass transfer coefficient for the waste water from a centrifuge rubber latex concentration unit

 

149

       G Madhu

 

 

 

Materials Science

 

Corrosion behaviour of sintered ferrous alloys and Ferro-TiC in H2SO4 and NaCl solutions

 

153

       M Debata & G S Upadhyaya

 

 

 

Preparation and properties of Al2O3/Al in-situ composites by reactive melt penetration

161

  V Venkateswara Rao

 

 

 

Effect of structure of nadimides on properties of glass fibre reinforced composites

165

  Anju Srivastava & I K Varma

 

 

 

Selective flocculation separation of iron and titanium from Kutch kaolins (India)

170

  G V S S Kumar, S K Menon, Y K Agrawal & S B Vora

 

 

 

Electrical properties of MoO3 films

177

  K Srinivasa Rao, K V Madhuri, S Uthanna, B S Naidu & O M Hussain

 

 

 

Effect of acidic environment on slake durability of iron ore—An experimental approach

 

182

  T N Singh, N Madhusudhan & M Monjezi

 

 


Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp. 123-128

 

Revisit to the stability of a uniform cantilever column subjected to
Euler and Beck loads—Effect of realistic follower forces

G Venkateswara Rao & Gajbir Singh

Structural Engineering Group, Vikram Sarabhai Space Centre, Trivandrum 695 022, India

Received 25 August 2000; accepted 28 March  2001

The stability of a uniform cantilever column subjected to Euler and Beck loads is investigated for its practical significance and reported here. A classical solution to the system of equations of motion and constraints pertaining to the problem is presented in detail.  The transcendental equation, so obtained, is solved using MAPLE-V software and interaction curves between Euler load and Beck load are plotted. The physical significance of these interaction curves is also discussed.


Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp. 129-135

 

Effect of split injection on diesel engine pollutants using multi-zone model

G Devaradjane

Department of Automobile Engineering, Anna University, M.I.T. Campus, Chennai 600 044, India

Received 15 May 2000; accepted 28 February 2001

A four zone model based on the existing two zone model is developed to predict the formation of the pollutants like nitric oxide, carbon monoxide and soot from the fuel injection data and engine geometry. The four zones are fuel zone, stoichiometric burning zone, product/air zone and a non-burning zone outside the spray. Whitehouse combustion model and Annand's heat transfer model are used for the prediction of combustion parameters like pressure and temperature of the engine. Equilibrium calculations and rate kinetics are used for the rate calculation of nitric-oxide. Nagle Strickland constable oxidation mechanism has been used for predicting the formation and emission of soot.


Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp. 136-140

 

Measure of parallelism for in-parallel robotic structures

A C Rao & Anne Jagadeesh

Koneru Lakshmaiah College of Engineering, Vaddeswaram, K.C Works P.O, Tadepalli Mandal, Guntur 522 502, India

Received 10 May 2000; accepted 11 January 2001

Multi-degree-of-freedom (d.o.f.) planar kinematic chains can be considered for application as in-parallel robots in view of their greater rigidity. A number of distinct chains are available with the same number of links and degree-of-freedom for consideration as in-parallel structures. Hence, it becomes necessary to know which of these chains are more in-parallel so that selection of the chains for the specified task such as work space, rigidity becomes easy. A simple and logical method is presented in this paper to accomplish the same. The efficiency of parallel systems is high and component velocities are less but this aspect is not dealt with since they are well-established. Measure of parallelism developed in this paper enables comparison of distinct chains for these characteristics also.


Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp. 141-148

 

Effect of aspect ratio and curvature on characteristics of S-shaped diffusers

 

Vinit Gupta, Rajneesh Devpura, S.N. Singh* & V Seshadri

Applied Mechanics Department, Indian Institute of Technology, New Delhi 110 016, India

Received 7 June 2000; accepted 26 February 2001

Performance characteristics of S-shaped rectangular diffusers have been investigated using CFD. The characteristics have been obtained for 15°/15°, 22.5°/22.5°, 30°/30°, 45°/45° and 90°/90° diffusers for constant circular center line length of 600 mm having an aspect ratio of 2, 4 and 6 at inlet. It is observed that as the curvature increases, the uniformity of flow at the outlet reduces, the cross flow velocities at the outlet increase and the coefficient of pressure recovery decreases. The effect of aspect ratio on the performance characteristics of these diffusers is also similar, i.e. reduction in aspect ratio reduces flow uniformity and pressure recovery.


Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp. 149-152

 

Determination of mass transfer coefficient for the waste water from a centrifuge rubber latex concentration unit

G Madhu

Process Engineering Department, FACT Engineering and Design Organisation, Udyogamandal 683 501, India

Received 2 May 2000; accepted 28 February 2001

During the concentration of natural rubber latex by centrifuging, considerable quantity of waste water is generated. Mass transfer coefficient is an important parameter in the design of a biological waste water treatment system based on aeration. This paper deals with the experimental determination of mass transfer coefficient for the waste water generated during the concentration of natural rubber latex by centrifuging. The determination of alpha, the ratio of mass oxygen transfer coefficient in waste water to that in clean tap water under identical conditions is also discussed in the paper. The effects of various parameters on the alpha value are also discussed.


Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp. 153-160

 

Corrosion behaviour of sintered ferrous alloys and Ferro-TiC in H2SO4 and NaCl solutions

M Debata & G S Upadhyaya

Department of Materials and Metallurgical Engineering, Indian Institute of Technology, Kanpur 208 016, India

Received 5 September 2000; accepted 4 April 2001

The room temperature corrosion behaviour of plain carbon steel Fe-0.5C, low alloy steel Fe-5Cu-0.5C, tool steels ASP 23 and ASP 30, and ferro-TiC cermet was investigated in H2SO4 (0.1-5 N) and 0.6 N NaCl solutions by potentiodynamic polarization technique. The study also includes X-ray diffraction, optical microscopy and scanning electron microscopy of the as-received as well as corroded surfaces. Porosities present in Fe-0.5C and Fe-5Cu-0.5C steels were found to be responsible for their poor corrosion resistance. ASP 30 steels were found to exhibit good corrosion resistance as compared to ASP 23 in both the media.


Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp 161-164

 

Preparation and properties of Al2O3/Al in-situ composites by reactive melt penetration

 

V Venkateswara Rao

National Metallurgical Laboratory, Jamshedpur 831 007, India

Received 6 January 2000; accepted 19 February 2001

Al2O3/Al ceramic matrix in-situ composites were prepared by reacting vitreous silica, mullite, or fireclay preforms with molten aluminium. Microstructure of the composites was found to consist of a network of aluminium channels embedded in the ceramic  matrix. Properties of the composites like density, hardness, and fracture toughness were determined. Composites made from vitreous silica exhibited low hardness, relatively easy machinability and improved fracture toughness. The process is suitable for producing net-shape or near net-shape composites.


Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp. 165-169

 

Effect of structure of nadimides on properties of glass fibre reinforced composites*

 

Anju Srivastavaa & I K Varmab

aDepartment of Chemistry, Hindu College, Delhi University, Delhi110 007, India.

bCentre for Polymer Science and Engineering, Indian Institute of Technology,

Hauz Khas, New Delhi 110 016, India.

Received 11 October 2000; accepted 1 March 2001

 

The paper describes fabrication of glass fibre reinforced laminates based on three structurally different nadimide oligomers containing phosphine oxide in the backbone and a low molecular weight low viscosity allyl nadicimide resin. Fabrication of laminates was done using methyl ethyl ketone solvent. Interlaminar shear strength and flexural strength of laminates, containing 0.67-0.5 volume fraction of fibres, depended on the structure of the resin and was found to be higher in laminates based on resins with higher polarity and having phosphine oxide in backbone. Properties of composites based on blends of these resins could be predicted on the basis of rule of mixtures. A marginal synergism was observed in one case. Tg was in the range of 230-270°C and was found to increase marginally in blends. Effect of oven aging and boiling water treatment on the properties of composites is also reported.


 

Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp. 170-176

 

Selective flocculation separation of iron and titanium from Kutch kaolins (India)

G V S S Kumara, S K Menona, Y K Agrawala* & S B Vorab

aChemistry Department, School of Sciences, Gujarat University, Ahmedabad 380 009, India

bGMDC Science and Research Centre, Ahmedabad 380 009, India

Received 17 February 2000; accepted 14 February 2001

A new selective flocculation separation (SFS) scheme has been described for upgrading Mamuara kaolins of Gujarat (Kutch district), India. The process embodies the implementation of polvinylpyrrolidone (PVP) as dispersant, carboxymethyl cellulose(CMC) as flocculant and new class of supramolecules such as hexasulfonato calix(6)arene [HSC(6)] as enriching agent.

Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp. 177-181

 

Electrical properties of MoO3 films

K Srinivasa Rao, K V Madhuri, S Uthanna, B S Naidu & O M Hussain*

Thin Film Laboratory, Department of Physics, S V University, Tirupati - 517 502, India

Received 25 February 2000; accepted 9 April 2001

DC conductivity of thin films of MoO3, prepared by activated reactive evaporation technique, revealed electron hopping conduction at lower temperature and the intrinsic thermally activated process at higher temperature. The dielectric properties of Al/MoO3/Al thin film sandwich structures were studied in the frequency range 0.050-100 kHz and in the temperature range 80-400 K. The frequency and temperature dependences of capacitance and dielectric loss were also studied.

Indian Journal of Engineering & Materials Sciences

Vol. 8, June 2001, pp. 182-184

 

Effect of acidic environment on slake durability of
iron ore — An experimental approach

T N Singh*, N Madhusudhan & M Monjezi

Department of Mining Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221 005., India

Received 18 August 2000; accepted 2 March 2001

Forces of weathering and erosion reduce the strength of rocks leading to various types of failures in slopes and strata. The present paper deals with the variation in the strength of iron ore bearing rocks with the acidity of the solutions to which they are exposed. Slake durability index is a measure of the durability of the rock when exposed to a slaking fluid medium. The variations in the slake durability indices of iron ore samples were studied by exposing them to acidic solutions of different pH values. The results indicate that the slake durability of iron ore rocks decreases with increase in the acidity of the solutions to which they are exposed. This behaviour is attributed to combined forces of weathering and corrosion acting on iron ore in acidic slaking media.

 

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