Indian Journal of Engineering & Materials Science
VOLUME 12CODEN : IEMSEW |
NUMBER 5
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OCTOBER 2005 ISSN : 0971-4588 |
CONTENTS
Engineering
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Long crack growth
mechanisms in Ti-6Al-4V alloy |
367 |
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[IPC Code: C22C 14/00] |
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Combined
characteristic-based split algorithm and mesh adaptation technique for
high-speed compressible flow analysis |
376 |
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Parinya
Boonmarlert, Sutthisak Phongthanapanich &
Pramote Dechaumphai |
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[IPC Code: F15B] |
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Flow analysis in a model can-type
gas turbine combustor |
389 |
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[IPC Code: F15D] |
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Interference effects on
wind pressures on low-rise and high-rise square structures in side-by-side
arrangement |
398 |
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[IPC Code: F15D 1/10, G01M 1/00] |
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Analysis of probabilistic
low cycle fatigue design curves at strain cycling |
411 |
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[IPC Code: G01N 3/00] |
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Behaviour
of the model surface strip footing on reinforced sand |
419 |
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[IPC Code: E02D 1/00] |
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Behaviour of slurry
infiltrated fibrous concrete (SIFCON) simply supported two-way slabs in
flexure |
427 |
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[IPC Code: C04B 14/38] |
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Comparison of three
back-propagation training algorithms for two case studies |
434 |
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[IPC
Code: G06N 3/02] |
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Materials Science |
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Influence
of fibre proportion and position on the machinability of GFRP composites- An
FEA model |
443 |
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[IPC
Code: C08B, G01N 3/58] |
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Fracture
criterion developed for elastic-plastic Russian materials |
451 |
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[IPC
Code: G01N] |
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Effect of
high density polyethylene on the permanent deformation of asphalt concrete |
456 |
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[IPC
Code: C04B26/00] |
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Persistent photoconductivity in a-Se90Ge10-xInx
thin films |
461 |
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[IPC
Code: H01L 27/00] |
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Synthesis,
characterization and thermolysis of 2,4-dihydro
-2,4,5-trinitro-3H-1,2,4-triazol-3-one (DTNTO): A new derivative of
3-nitro-1,2,4- triazol-5-one (NTO) |
467 |
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H S
Jadhav, M B Talawar, D D Dhavale,
S N Asthana & V N Krishnamurthy |
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[IPC
Code: C06B] |
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Note
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Failure
assessment of a driven shaft of an extrusion gear pump |
472 |
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[IPC
Code: F16C] |
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__________________ |
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IPC: International Patent
Classification |
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Int. Cl.7: International Classification
7th edition, 1999 |
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Indian Journal of Engineering & Materials Sciences
Vol.
12, October 2005, pp. 367-375
Long crack growth mechanisms in Ti-6Al-4V alloy
T Goswami
A transition mechanism of long crack growth from structure
sensitive (Regime I) to insensitive region (Regime II) was investigated at (i)
room temperature under high humidity conditions, and (ii) elevated temperatures
for Ti-6Al-4V alloy and other materials. Constant amplitude tests were
conducted using several stress ratios (R =
0.05, 0.1, 0.4 and 0.7) for the high humidity tests and 0.1 for room and
elevated temperature tests. Conventionally forged Ti-6Al-4V alloy disks,
processed to the solution treated and over-aged condition, were studied for both
programs. An increase in stress ratio and temperature lowered the transitional
stress intensity factor range where Regime I transitioned to Regime II. Higher
stress ratios (R = 0.7) accelerated
the fatigue crack growth rates many times the crack growth rates obtained at
lower stress ratios (R = 0.05).
However, higher temperatures (345ºC) influenced the crack growth rates only
marginally. The mechanisms controlling elevated temperature fatigue crack
growth in Ti-6Al-4V were by the secondary crack formation, striations and some
cavity features on the fracture surface. The damage was localized on the a platelets, where a type dislocations found
with the Burgers vectors (a/2) <11
0> g = 1010 near (10
0).
IPC Code: C22C14/00
Indian Journal of Engineering & Materials Sciences
Vol.
12, October 2005, pp. 376-388
Combined characteristic-based split algorithm and
mesh adaptation technique for high-speed compressible flow analysis
Parinya Boonmarlert, Sutthisak Phongthanapanich & Pramote Dechaumphai
The characteristic-based split algorithm is combined with a mesh adaptation technique to analyze high-speed inviscid compressible flow problems. The solution accuracy is improved by coupling an error estimation procedure to an adaptive remeshing technique that generates small elements in regions with large change in solution gradients, and at the same time, larger elements in the other regions. The efficiency of the combined procedure is evaluated by solving several problems for both transient and steady-state flow behaviours.
IPC Code: F15B
Indian Journal of Engineering & Materials Sciences
Vol.
12, October 2005, pp. 389-397
Flow analysis in a model can-type gas turbine combustor
Abhishek Jain, Sidharth Choudhary, S N
Singh & Lajpat Rai
Flow analysis has been carried out in a model can-type gas turbine combustor using a commercial computational fluid dynamics (CFD) code. The code has been validated against the experimental results quoted in the literature and part of the present study. The comparison has shown that CFD code can be effectively used to carry out parametric investigations on the complete combustor model for the combustor design.
IPC Code: F15D
Indian Journal of Engineering & Materials Sciences
Vol.
12, October 2005, pp. 398-410
Interference effects on wind pressures on low-rise and high-rise square structures in side-by-side arrangement
J Lakshminarasimhan, B H Lakshmana Gowda & Ch Sivannarayana
In this paper, the effects of interference on three-dimensional bluff bodies with square cross-section placed in side-by-side arrangement for a low-rise body and a high-rise body have been investigated experimentally. The extent of interference effects are brought out by varying the spacing between the bodies. The pressure distributions on the surfaces of the bodies are measured to bring out the severity of interference due to another body adjacent to it. The bodies are exposed to an air stream with a velocity profile satisfying the 1/7th power law. It is seen that the pressure distribution on rear side and interference side is greatly affected for low-rise body when interfered by a high-rise body in close proximity.
IPC Code: F15D1/10,G01M1/00
Indian Journal of Engineering & Materials Sciences
Vol. 12, October 2005, pp. 411-418
Analysis of probabilistic low cycle fatigue design curves at strain cycling
Zilvinas Bazaras
In this investigation, low cycle fatigue tests were carried out and mechanical characteristics of three materials (steel of grades 15X2MFA and 45 and aluminium alloy D16T1), representing all possible variations of cyclic properties (fatigue, quasi-static and intermediate mode of fracture) were determined experimentally. Based on the data obtained, design curves of equal fracture probability for steels 15X2MFA and 45 and aluminium alloy D16T1 at low cycle strain-controlled loading were generated and the design curves were compared with experimental data. Analysis of calculated and experimental low cycle fatigue curves constructed according to the fracture probability parameter, revealed that the use of analytical relationships for lifetime assessment of structures may lead to an error and decreasing safety margin. It is recommended to use experimental 50% fracture probabilistic curves in lifetime assessment of power equipment structures.
IPC
Code: G01N3/00
Indian Journal of Engineering & Materials Sciences
Vol.
12, October 2005, pp. 419-426
Behaviour
of the model surface strip footing on reinforced sand
Berkan Moroglu, Bayram Ali Uzuner & Erol Sadoglu
A series of tests were carried out with an eccentrically loaded model surface strip footing on un-reinforced and reinforced dense sand to investigate the behaviour of the footing (decrease in ultimate load with increasing eccentricity, failure surfaces and load displacement relations). The experimental set-up used to run the tests consists of tank, model footing, sand and loading mechanism. A single woven geotextile strip sheet was placed horizontally below the footing’s base at a depth half of the footing’s width. The primary failure surfaces occurred at the eccentricity side for this laterally unrestricted footing. The use of this reinforcement increased the ultimate load by about 50% for centrally loaded strip footing in comparison with un-reinforced case and its contribution to ultimate load decreased as eccentricity increased in these conditions. Geotextile not only increased ultimate load, but also increased necessary amount of vertical displacement of footing to reach failure compared with un-reinforced case. The experimental results are in good agreement with Meyerhof’s effective width concept than the customary analysis and the customary analysis is unsafe outside the core.
IPC Code: E02D1/00
Indian Journal of Engineering & Materials Sciences
Vol.
12, October 2005, pp. 427-433
Behaviour of slurry infiltrated fibrous concrete (SIFCON) simply supported two-way slabs in flexure
H Sudarsana Rao & N V Ramana
Slurry infiltrated fibre concrete (SIFCON) is one of the recently developed construction material. SIFCON could be considered as a special type of fibre concrete with high fibre content. The matrix consists of cement slurry or flowing cement mortar. This composite material has already been used for structures subjected to blast loading, repair of pre-stressed concrete beams and safe vaults1. This paper presents the information on behaviour of two-way slabs in flexure. Flexure and cyclic load tests have been conducted and compared with fibre reinforced concrete (FRC) and plain concrete slabs. Both strength and deflection characteristics have been studied. The results of the experimental investigation indicate that with 12% fibre by volume of matrix slabs possess excellent performance among other slabs in all respects.
IPC Code: C04B14/38
Indian Journal of Engineering & Materials Sciences
Vol.
12, October 2005, pp. 434-442
Comparison of three back-propagation training algorithms for two case studies
Özgür Kişi & Erdal Uncuoğlu
This paper investigates the use of three back-propagation training algorithms, Levenberg-Marquardt, conjugate gradient and resilient back-propagation, for the two case studies, stream-flow forecasting and determination of lateral stress in cohesionless soils. Several neural network (NN) algorithms have been reported in the literature. They include various representations and architectures and therefore are suitable for different applications. In the present study, three NN algorithms are compared according to their convergence velocities in training and performances in testing. Based on the study and test results, although the Levenberg-Marquardt algorithm has been found being faster and having better performance than the other algorithms in training, the resilient back-propagation algorithm has the best accuracy in testing period.
IPC Code: G06N3/02
Indian Journal of Engineering & Materials Sciences
Vol.
12, October 2005, pp. 443-450
Influence of fibre proportion and position on the machinability of GFRP composites- An FEA model
D Abdul Budan
More commonly considered criteria for judging the machinibility are the cutting forces on the tool and power consumption. A classical Merchant’s model is widely used to predict the cutting forces while machining isotropic material. However, no such model exists to predict the cutting forces while machining orthotropic materials. In this paper, an effort is made to modify the Merchant’s formula by incorporating the K-factor to evaluate the shear strength, the fibre orientation as shear angle and a constant coefficient of friction. The cutting forces evaluated by modified Merchant’s model on unidirectional GFRP composite material has been compared with the results predicted by two-dimensional FEA model. In FEA model both maximum stress and Tsai-Hill failure criteria were used to simulate the chip separation. The influence of composite design, in particular the fibre proportion and orientation on cutting forces has been investigated. The higher fibre proportion in the composite caused an increase in cutting force values. Fibre orientations 45° and 60° have shown favorable results. The FEA predicted results have shown good agreement with the results evaluated by modified Merchant’s model.
IPC
Code: G01N3/58, C08B
Indian Journal of Engineering & Materials Sciences
Vol. 12, October 2005, pp. 451-455
Fracture criterion developed for elastic-plastic Russian materials
A Ziliukas
One of the ways to maximize the safety of metal structures and components is to use elastic-plastic materials instead of brittle ones. The use of such materials reduces the probability of catastrophic failure occurring from crack like flaws that may have resulted from the manufacturing process or during the operational life. However, within the field of fracture mechanics, the criterion of brittle fracture is more developed than brittle-plastic fracture criteria. This paper deals with the analysis of universal fracture criteria, which are suitable not only for elastic materials with the brittle fracture, but also for elastic-plastic materials with the elastic-plastic fracture. An analytical two-parametrical fracture criterion has been proposed for static loading, which is validated experimentally and compared with the behaviour of perfectly plastic and elastic specific Russian materials. It allows the fracture resistance of structural components made of elastic-plastic materials to be evaluated more precisely.
IPC Code: G01N
Indian Journal of Engineering & Material Sciences
Vol.
12, October 2005, pp. 456-460
Effects
of high density polyethylene on the permanent deformation of
asphalt concrete
Sinan Hinislioğlu, Hatice Nur Aras, Osman Ünsal Bayrak
This paper reports an investigation about
the effect of high density polyethylene (HDPE) in powder form as a bitumen
modifier on the permanent deformation of asphalt concrete using Marshall design
parameters and creep behaviour. The parameters assessed are the compacted mix
density, the percentage of air voids in the mixture, the percentage of void in
the mineral aggregate, the percentage of voids filled with bitumen, Marshall
stability and flow and also Marshall quotient (MQ), axial strain and stiffness
modulus. It is also investigated
the effect of HDPE on some physical properties such as penetration, softening
point and ductility. Bitumen is mixed with the HDPE at
1-4% by weight of bitumen at 185°C for
60 min. duration using a high shear mixer. Marshall samples prepared with the
HDPE modified binder provide the specification limits. The addition of 3% HDPE,
results in an increase of 57% in Marshall quotient. In addition, it has been
observed that the use of 2% HDPE decreased the permanent strain by 34% and
increased the creep stiffness by 52%. The creep recovery values of the asphalt
concrete with HDPE after 15 min have been found to be higher than control
mixtures. It can be concluded that HDPE modified asphaltic binders provide
better resistance against permanent deformation, because of their higher
stability and stiffness, relatively lower flow. As a result, HDPE modified
asphaltic binders are considered to be very useful in mitigating permanent
deformation in hot climate regions.
IPC Code: C04B 26/00
Indian Journal of Engineering & Materials Sciences
Vol. 12, October 2005, pp. 461-466
Persistent photoconductivity in a-Se90Ge10-xInx thin films
Sangeeta Singh, R K Shukla & A Kumar
Transient photoconductivity has been studied in amorphous Se90Ge10-xInx thin films prepared by vacuum evaporation. It is observed that the decay of photoconductivity is quite slow in these samples. A persistent photoconductivity, with an extremely slow decay rate is also observed during decay process. The magnitude of persistent photoconductivity increases with increase in illumination time, intensity of light and temperature of the films. The results indicate that some kind of photo induced structural changes occur in these samples, which are of reversible nature and have time constants of a few hours. Studies made on various compositions under identical conditions show that the persistent photoconductivity is minimum at 4 at. % of Indium. This discontinuity at an average coordination number <Z> = 2.2 is closer to the value suggested by topological models based on constraints theory.
IPC Code: H01L27/00
Indian Journal of Engineering & Materials Sciences
Vol.
12, October 2005, pp.467-471
Synthesis,
characterization and thermolysis of 2,4-dihydro
-2,4,5-trinitro-3H-1,2,4-triazol-3-one (DTNTO): A new derivative of 3-nitro-1,2,4-triazol-5-one
(NTO)
H S Jadhav, M B Talawar, D D Dhavale, S N Asthana & V N
Krishnamurthy
A new derivative of
3-nitro-1,2,4-triazol-5-one (NTO, 2), viz., 2,4-dihydro-2,4,5-trinitro-3H-1,2,4-triazole-3-one
(DTNTO, 3) has been obtained by
nitration of NTO synthesized during this work using fuming nitric acid and
acetic anhydride. The title compound 2 was obtained from 2,4-dihydro-3H-1,
2,4-triazol-3-one (TO, 1). The newly synthesized DTNTO has been characterized
by elemental analysis, IR, 1H and 13C NMR. The DTA and
DSC of (3) showed exothermic
decomposition with peak temperature (Tmax)
of 264oC. TG showed 61% weight loss for 3 in the temperature range of
194-264oC. The sensitivity data obtained for the newly synthesized
compound indicates its relatively high susceptibility towards external stimuli
(Impact height, h50% explosion
80 cm, 3 kg drop weight and friction insensitive up to 25 kg) in comparison to
NTO (h50% >100 cm, 3 kg
drop weight and friction insensitive up to 36 kg). The theoretically predicted
performance of compound 3 in terms
of velocity of detonation (8.79 km/s) is intermediate to that of NTO (8.75
km/s) and RDX (8.93 km/s). The calculated CJ pressure and sound intensity for
DTNTO are found superior in comparison to benchmark high explosives RDX and
HMX. Its positive oxygen balance is an attractive feature from the point of
view of its application as an eco-friendly oxidizer in propellant formulations.
IPC
Code:C06B
Indian Journal of Engineering & Materials Sciences
Vol. 12, October 2005, pp. 472-474
Failure
assessment of a driven shaft of an extrusion gear pump
K L Barui & B Bhattacharya
The paper deals with the investigation of failure of a driven shaft made of BS 970-1991 Series 080 M40 (BS 970-1955 Series En 8) grade steel. It broke after 1100 h run while pumping out liquid polythene under normal operating condition. Metallurgical investigation reveals Widmanstatten pattern and very coarse grains enveloped with ferrite, though the chemical and physical properties of the material are satisfactory. Presence of such microstructure due to elevated finishing temperature of the forging process causes brittle fracture. The suggested remedial measure is to keep the finishing temperature just above the lower critical temperature.
IPC Code: F16C