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Indian Journal of Engineering & Materials Sciences

 

 

 

ISSN : 0971-4588

VOLUME 11

 

NUMBER 6

CODEN : IEMSEW

DECEMBER 2004

 

 

CONTENTS

  

Engineering

 

 

Effect of orientation on the wake of a square cylinder at low Reynolds numbers

447

Sushanta Dutta, P K Panigrahi & K Muralidhar

 

[IPC Code: Int. Cl.7 F 15D]

 

 

 

Thermal post buckling behaviour of tapered columns—A simple solution

460

K Kanaka Raju & G Venkateswara Rao

 

[IPC Code: Int. Cl.7 F 16S, E 04C 3/30]

 

 

 

An investigation on the applicability of Cartesian grid approach to calculate flow over arbitrary terrain

 

465

S Vengadesan, A Nakayama & S Yokojima

 

[IPC Code: Int. Cl.7 G 01F 1/00, F 15D]

 

 

 

Property analysis and mathematical modeling of machining properties of aluminium alloy hybrid (Al-alloy/SiC/flyash) composites produced by liquid metallurgy and powder metallurgy techniques

 

 

473

S Charles & V P Arunachalam

 

[IPC Code: Int. Cl.7 C 22C 49/06]

 

 

 

Stabilising dimensions of brass powder components

481

Akhter H Ansari, M Hameedullah & M S J Asghar

 

[IPC Code: Int. Cl.7 B 22F 3/02]

 

 

 

An investigation on forging loads and metal flow in conventional closed-die forging of preforms obtained by open-die indentation

 

487

Yilmaz Can, M Tahir Altinbalik & H Erol Akata

 

[IPC Code: Int. Cl.7 B 21K]

 

 

 

Performance assessment of draglines in opencast mines

493

Piyush Rai

 

[IPC Code: Int. Cl.7 E 02F 3/48, E 21C 47/00]

 

 

 

Materials Science

 

 

Decolourisation of metal complex azo dyes and treatment of a dyehouse waste by modified photo-Fenton (UV-vis/ferrioxalate/H2O2) process

 

499

Pooja Tripathi & Malay Chaudhuri

 

[IPC Code: Int. Cl.7 C 09B 57/10]

 

 

AC impedance studies on the molecular semiconductors based on aromatic diamines-iodine charge-transfer complexes

 

505

R K Gupta & R A Singh

 

[IPC Code: Int. Cl.7 H 03H 9/00, H 01L]

 

 

 

A study of the crystallization kinetics in Se68Ge22Pb10 chalcogenide glass

511

N Mehta, P Agarwal & A Kumar

 

[IPC Code: Int. Cl.7 C 03C]

 

 

 

N,N˘-Bis(1,2,4-triazol-3-yl-)-4,4˘-diamino-2,2˘, 3,3˘, 5,5˘, 6,6˘-octanitroazo-benzene (BTDAONAB): A new thermally stable insensitive high explosive

 

516

Mehilal, N Sikder, A K Sikder & J P Agrawal

 

[IPC Code: Int. Cl.7 C 06B 25/00]

 

 

 

Temperature dependence of the viscosity of In-Sb alloy melts

521

 S J Chengb, X F Bian, X B Qin & P C Si

 

[IPC Code: Int. Cl.7 C 22C, C 21D 9/00]

 

__________

 

IPC: International Patent Classification

 

Int. Cl.7: International Classification 7th edition, 1999

 

 

 

  

Indian Journal of Engineering & Materials Sciences

Vol 11, December 2004, pp. 447-459

Effect of orientation on the wake of a square cylinder at low Reynolds numbers

Sushanta Dutta, P K Panigrahi & K Muralidhar

 

Experimental investigation of flow past a square cylinder at Reynolds numbers of 97 and 187 is reported. Cylinder orientations of 0 to 60o with respect to the mean flow have been considered. Two-component hotwire anemometry has been adopted for velocity measurements. The wake of the cylinder has been visualized using a pulsed laser sheet to understand the flow structure. Measurements have been carried out in the near wake, mid-wake and far wake of the cylinder. The effects of orientation and Reynolds number on Strouhal number, drag coefficient, time-average and rms velocity distributions, decay of velocity fluctuations and power spectra are of interest. There is a dominant peak of vortex shedding in the near wake velocity spectra over the range of Reynolds numbers studied. The Strouhal number and drag coefficient are correlated to the cylinder angle. A change in the cylinder orientation leads to an early appearance of quasi-periodicity and hence three-dimensionality, owing to the asymmetric nature of the wake. The shape of the mean velocity profiles, fluctuations and the rate of decay show a strong dependence on the cylinder orientation in the near wake, though the dependence weakens in the far wake. Among the angles studied, the wake of a cylinder whose orientation is 22.5o with respect to the incoming flow is surprisingly vigorous, and shows strong three-dimensionality. The data of the present work is useful for assessing flow interaction with cylindrical structures of square cross-section.

 

IPC Code: Int. Cl.7 F15D

 

 

 

Indian Journal of Engineering & Materials Sciences

 Vol. 11, December 2004, pp. 460-464

 

Thermal post-buckling behaviour of tapered columns—A simple solution

K Kanaka Raju & G Venkateswara Rao*

 

The applicability of a simple method proposed earlier by the authors to predict the thermal post-buckling behaviour of structural elements has been demonstrated in this paper for the case of tapered columns. Numerical results are presented to show the accuracy of the method along with comparable finite element results. Both depth and diameter tapered columns are considered with simply supported and clamped boundary conditions.

IPC Code: Int. Cl.7 F16S, E04C 3/30

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, December 2004, pp. 465-472

 

An investigation on the applicability of Cartesian grid approach to calculate flow over arbitrary terrain

 

S Vengadesan, A Nakayama  & S Yokojima

 

An investigation is made on the applicability of method of representing by Cartesian grid to calculate flow over natural terrain. Model hill geometry with different maximum slope angles is chosen and calculations by both Cartesian and Boundary-fitted coordinate representations are made. Computations are performed for laminar flow at different Reynolds numbers and turbulent flow conditions. Results in terms of mean velocity distribution, streamline, vorticity distribution and velocity vector close to the surface are analyzed and discussed. The study indicates that to calculate flow over undulating natural terrain, rectangular coordinate method of representing the geometry is able to capture most of the flow phenomena and it can be a viable alternative.

IPC Code: Int Cl.7 G01F 1/00, F15D

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, December 2004, pp. 473-480

 

Property analysis and mathematical modeling of machining properties of  aluminium alloy hybrid (Al-alloy/SiC/flyash) composites produced by liquid metallurgy and powder metallurgy techniques

S Charles & V P Arunachalam

 

Aluminium hybrid composites reinforced with silicon carbide and flyash particulates were fabricated by stir casting and powder metallurgy methods. Different volume fractions of SiC particles (10, 15 and 20 vol%) and constant volume fraction of flyash (10 vol%) were used for the synthesis. Wear, micro hardness, tensile and microstructural properties were studied. Results of the investigations indicated that wear resistance and hardness were enhanced on increasing the vol% of SiC. The tensile strength was high at 10 vol% of SiC and it decreased as the vol% increased. Microstructure showed a fairly uniform distribution of the dispersoids. Electric discharge machining was done on the composite specimens and mathematical models were developed for predicting the material removal rate and tool wear rate using design of experimentation with current, pulse duration and vol% of SiC as the process variables. Curves describing the direct and interaction effect of the process variables were drawn. It was found that the material removal rate and tool wear rate increased with increase in current and decreased with increase in pulse duration and vol% of SiC. The behaviour of the composites was similar both for powder metallurgy and stir casting, except the fact that stir cast specimens exhibited higher hardness, wear resistance and tensile strength. This increase can be attributed to the close interfacial bonding of stir cast specimens.

 

IPC Code:  C22C 49/06

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, December 2004, pp. 481-486

 

Stabilising dimensions of brass powder components

Akhter H Ansari, M Hameedullah & M S J Asghar

 

Powder metallurgy components are manufactured by compacting metal powders. Hence, compaction pressure affects the properties of the components. In the present case, pre-alloyed cartridge brass (70:30) powder is employed for investigation and the effect of compaction pressure on dimensional properties of components is studied. A volumetric shrinkage is observed at various levels of compaction pressure. The shrinkage reduces with an increase in compaction pressure. It is 1.0% at 242 MPa, which reduces further to 0.4% at 725 MPa. At high level of compaction pressure, the shrinkage is found along the diameter. A swelling of 1.0% in diameter is exhibited at low level.

 

IPC Code: Int. Cl.7 B22F 3/02

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, December 2004, pp. 487-492

 

An investigation on forging loads and metal flow in conventional closed-die forging of preforms obtained by open-die indentation

Yilmaz Can, M Tahir Altinbalik & H Erol Akata

 

In this paper, an experimental study has been carried out to investigate the effectiveness of the usage of the open die indented specimen as preforms of conventional closed die forging. Cylindrical billets having two different aspect ratios (H0/D0) are indented with two different ratios and thereafter forged using a conventional closed-die set-up. Effects of indentation and aspect ratios on forging load and on die filling have been observed and compared with reported results.

 

IPC Code: B21K

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, December 2004, pp. 493-498

 

Performance assessment of draglines in opencast mines

Piyush Rai

 

The present paper investigates a few important productivity parameters of draglines operating in some major opencast coal-mines in India. The parameters, such as, average total cycle time, availability, utilization, annual output and influence of fragmentation on the overall performance of the draglines, have been critically analyzed with studies in mines. The results indicate that there is a considerable scope for improvement in performance of draglines mines by reducing the cycle time, improving the maintenance strategies, reducing the idling losses and improving the degree of fragmentation, especially at the collar regions.

 

IPC Code: Int. Cl.7 E02F 3/48, E21C 47/00

 

 

 

Indian Journal of Engineering & Materials Sciences

 Vol. 11, December 2004, pp. 499-504

  

Decolourisation of metal complex azo dyes and treatment of a dyehouse waste by modified photo-Fenton (UV-vis/ferrioxalate/H2O2) process

Pooja Tripathi & Malay Chaudhuri

 

In a laboratory study, decolourisation of three metal complex azo dyes (Acidol Yellow, Acidol Grey and Acidol Scarlet) in mixture by the modified photo-Fenton (UV-vis/ferrioxalate/H2O2) process, and treatment of a dyehouse waste containing the three dyes were examined. From decolourisation of the dye mixture, process conditions for decolourisation were selected – pH 4, Fe(III) dose 12.5 mg/L, oxalic acid dose 50 mg/L, hydrogen peroxide dose 60 mg/L and irradiation time 90 min. Ninety-two percent decolourisation of the dye mixture (colour 120 SU) occurred in 90 min under irradiation with sunlight intensity in the range 0.5-0.8 kW/m2. The process was found effective in decolourisation of highly coloured solutions. Modified photo-Fenton decolourisation of the synthetic dyehouse waste (pH 7.5, colour 120 SU, COD 260 mg O2/L, BOD5 125 mg/L, turbidity 1.5 NTU, conductivity 1265 mmho/cm and total solids 875 mg/L) under selected process conditions and irradiation with sunlight or incandescent lamp, was also studied. Ninety-two percent decolourisation (residual colour ca 10 SU) was achieved under 90 min irradiation with sunlight (0.5-0.8 kW/m2) or incandescent lamp (6.5 kW/m2). A depth of 30 cm was found to be the maximum depth for decolourisation. The study has demonstrated that modified photo-Fenton is an effective process for decolourisation of dyehouse waste containing metal complex azo dyes. A scheme for oxidative treatment of the dyehouse waste was formulated and the treatment efficiency was evaluated – 90-92% or 90-92%, 69-70% or 63-73%, and 52-65% or 50-60% removal of colour, COD and BOD5 were achieved under irradiation with sunlight or incandescent lamp.

 

IPC Code: Int. Cl.7 C09B 57/10

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, December 2004, pp. 505-510

 

AC impedance studies on the molecular semiconductors based on aromatic diamines-iodine charge-transfer complexes

R K Gupta & R A Singh

 

Molecular semiconductors based on charge-transfer complexes of benzidine, o-olidine and N, N'-diphenylbenzidine with iodine having different mole ratios have been prepared and characterized by thermal, spectral and electrical methods. The thermal decomposition behaviour of these materials indicate that they are thermally stable up to 130°C and then proceed to stoichiometric weight loss corresponding to iodine and aromatic diamines respectively. The electrical conductivity has its highest value for N, N'-diphenylbenzidine-iodine complexes and lowest for benzidine-iodine complexes which may be due to more extensive conjugation of radical cation in the former than in the later. Impedance studies show (RC)(RC), R (RC) and (RC) equivalent circuit for benzidine, o-tolidine and N, N'-diphenylbenzidine-iodine complexes respectively. The electrical data have been discussed in light of dynamic bond percolation model in which the distribution, density and availability of potential hopping sites change as a result of electronic and structural changes in the material.

 

IPC Code: Int. Cl.7 H03H 9/00, H01L

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, December 2004, pp. 511-515

  

A study of the crystallization kinetics in Se68Ge22Pb10 chalcogenide glass

N Mehta, P Agarwal & A Kumar

 

Differential scanning calorimetry (DSC) is performed at different heating rates under non-isothermal conditions to study the crystallization kinetics of Se68Ge22Pb10 chalcogenide glass. Different kinetic parameters such as the activation energy of crystallization (Ec), the order parameter (n), the rate constant and its frequency factor have been determined. Four different non-isothermal methods Kissinger’s method, Matusita-Sakka theory, Augis-Bennett approximation and Ozawa-Chen method have been used in the present study. The average value of activation energy of crystallization Ec is 1.477 eV. The average value of Avrami’s index n is 3.61, which indicates that in the glassy Se68Ge22Pb10, two crystallization (two- and three-dimensional growth) mechanisms are working simultaneously during its amorphous to crystalline transformation.

 

IPC Code: Int. Cl.7 C03C

 

 

 

Indian Journal of Engineering & Materials Sciences

 Vol. 11, December 2004, pp. 516-520

 

N,N˘-Bis(1,2,4-triazol-3-yl-)-4,4˘-diamino-2,2˘, 3,3˘, 5,5˘, 6,6˘-octanitroazo-benzene (BTDAONAB): A new thermally stable insensitive high explosive

Mehilal, N Sikder, A K Sikder & J P Agrawal

 

N,N˘-Bis(1,2,4-triazol-3-yl)-4,4˘-diamino-2,2˘, 3,3˘, 5,5˘, 6,6˘-octanitroazobenzene (BTDAONAB) has been synthesized by condensing 4,4˘-dichloro-2,2˘, 3,3˘, 5,5˘, 6,6˘-octanitroazobenzene (DCONAB) with 3-amino-1,2,4-triazole in methanol. The title compound has been characterized by elemental analysis and spectral data (IR and NMR). Some thermal and explosive properties of the compound have also been studied and the data indicate that the BTDAONAB possesses remarkable thermal stability and is, at the same time, safe for handling, transportation and storage.

 

IPC Code: Int. Cl.7 C06B 25/00

 

 

 

Indian Journal of Engineering & Materials Sciences

 Vol 11, December 2004, pp. 521-524

 

 Temperature dependence of the viscosity of In-Sb alloy melts

S J Cheng, X F Bian, X B Qin  & P C Si

 

The temperature dependence of the dynamic viscosity of In-Sb alloy melts has been investigated using a torsional oscillation viscometer. The results show that no anomalous change in viscosity occurs in In-1 wt.%Sb melt and an anomalous change occurs at about 800oC both in In-55 wt.%Sb and In-69.5 wt.%Sb alloy melts. A low temperature area (LTA) and a high temperature area (HTA) can be used to describe the viscosity behaviour of In-55 wt.%Sb and In-69.5 wt.%Sb alloy melts. The activation energy of In-Sb alloy melts has been obtained. Variation of activation energy with temperature of In-Sb melts has been observed. The structural variation of In-Sb alloy melts has also been discussed on the basis of the change in viscosity and DSC analysis.

 

IPC Code: Int. Cl.7 C22C, C21D 8/00