Indian Journal of Engineering & Materials Science


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VOLUME 12

CODEN : IEMSEW

NUMBER 5

OCTOBER 2005

ISSN : 0971-4588

 

CONTENTS

 

Engineering

 

Long crack growth mechanisms in Ti-6Al-4V alloy

367

        T Goswami

 

        [IPC Code: C22C 14/00]

 

 

 

Combined characteristic-based split algorithm and mesh adaptation technique for high-speed compressible flow analysis

 

376

        Parinya Boonmarlert, Sutthisak Phongthanapanich & Pramote Dechaumphai

 

        [IPC Code: F15B]

 

 

 

Flow analysis in a model can-type gas turbine combustor

389

        Abhishek Jain, Sidharth Choudhary, S N Singh & Lajpat Rai

 

        [IPC Code: F15D]

 

 

 

Interference effects on wind pressures on low-rise and high-rise square structures in side-by-side arrangement

 

398

        J Lakshminarasimhan, B H Lakshmana Gowda & Ch Sivannarayana

 

        [IPC Code: F15D 1/10, G01M 1/00]

 

 

 

Analysis of probabilistic low cycle fatigue design curves at strain cycling

411

        Zilvinas Bazaras

 

        [IPC Code: G01N 3/00]

 

 

 

Behaviour of the model surface strip footing on reinforced sand

419

        Berkan Moroglu, Bayram Ali Uzuner & Erol Sadoglu

 

        [IPC Code: E02D 1/00]

 

 

 

Behaviour of slurry infiltrated fibrous concrete (SIFCON) simply supported two-way slabs in flexure

 

427

        H Sudarsana Rao & N V Ramana

 

        [IPC Code: C04B 14/38]

 

 

 

Comparison of three back-propagation training algorithms for two case studies

434

        Özgür Kişi & Erdal Uncuoğlu

 

        [IPC Code: G06N 3/02]

 

Materials Science

 

 

 

Influence of fibre proportion and position on the machinability of GFRP composites- An FEA model

 

443

        D Abdul Budan

 

        [IPC Code: C08B, G01N 3/58]

 

Fracture criterion developed for elastic-plastic Russian materials

451

        A Ziliukas

 

        [IPC Code: G01N]

 

 

 

Effect of high density polyethylene on the permanent deformation of asphalt concrete

 

456

        Sinan Hinislioğlu, Hatice Nur Aras, Osman Ünsal Bayrak

 

        [IPC Code: C04B26/00]

 

 

 

Persistent photoconductivity in a-Se90Ge10-xInx thin films

461

        Sangeeta Singh, R K Shukla & A Kumar

 

        [IPC Code: H01L 27/00]

 

 

 

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

        H S Jadhav, M B Talawar, D D Dhavale, S N Asthana & V N Krishnamurthy

 

        [IPC Code: C06B]

 

 

 

Note

 

 

 

Failure assessment of a driven shaft of an extrusion gear pump

472

        K L Barui & B Bhattacharya

 

        [IPC Code: F16C]

 

__________________

 

IPC: International Patent Classification

 

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

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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) <110> g = 1010 near (100).

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