Engineering
& Materials Sciences
http : // www.niscair.res.in
VOLUME 16
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NUMBER 2
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APRIL 2009
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CODEN
: IEMSEW |
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ISSN : 0971-4588 |
CONTENTS
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Engineering |
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Collapse behaviour and simplified modeling of
triangular cross-section columns |
71 |
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Failure analysis of composite single bolted-joints
subjected to bolt pretension |
79 |
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Neuro-fuzzy modeling of hot extrusion process |
86 |
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Rheological properties of
fiber reinforced asphalt binders
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93 |
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Influence of size strength relation in modeling the
behaviour of quasi-brittle |
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materials |
100 |
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Materials
Science |
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High temperature oxidation and wear behaviour of
powder metallurgically |
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developed Ni-Cr-W-Al-Ti-MoS2 composite |
111 |
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An experimental investigation into the machinability
of |
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spheroidal graphite cast iron |
116 |
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Size dependent modifications in the physical
properties of chemical solution |
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deposition and pulsed laser deposition grown La0.7Ca0.3MnO3
manganite |
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thin films: A comparative study |
123 |
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J H
Marknaa, P S Vachhani, N A Shah, J John, D
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Study of surface morphology in DC and pulse plating
of silver alloy |
128 |
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C
Shanthi,
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Synthesis, characterization, curing and thermal
studies of phosphorylated |
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epoxy resins |
133 |
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Indian
Journal of Engineering & Materials Sciences
Vol.
16, April 2009, pp. 71-78
Collapse behaviour and simplified modeling of triangular cross-section columns
Yucheng Liu
This paper investigates and develops the collapse behaviours and characteristics of thin-walled columns with triangular cross-section under axial compression and pure bending. Two bending modes, inward bending and outward bending are discussed. The axial and bending resistances of the triangular columns are formulated with mathematical equations of simple forms. Simplified finite element models for the triangular columns are then developed based on the derived equations to simulate their axial buckling and bending collapse behaviours during crashes. The developed simplified models consist of beam elements and spring elements. Numerical results and comparisons show that the developed simplified models can replace detailed models in using for crashworthiness analysis and save a lot of computing time and modeling efforts. The presented simplified models and modeling efforts can be extensively applied in thin-walled structural analysis and design.
Keywords: Axial buckling, Bending collapse, Thin-walled column,
Triangular cross-section, Simplified model, Crashworthiness analysis
Indian
Journal of Engineering & Materials Sciences
Vol.
16, April 2009, pp. 79-85
Failure analysis of composite single bolted-joints subjected to bolt pretension
Murat Pakdil
In this study, failure analysis of composite single bolted joints has been performed. To determine effects of joint geometry and stacking sequences of laminated composite plates on bearing strength and failure mode, experimental studies have been carried out by which edge distance-to-hole diameter ratio (E/D), and plate width-to-hole diameter ratio (W/D) are varied from 1 to 5 and 2 to 5, respectively. In addition, bolt pretensions of 0, 3 and 6 Nm are applied. The composite laminated plates are stacked with the following four different orientations: [0o/0o/30o/30o]s, [0o/0o/45o/45o]s, [0o/0o/60o/60o]s, and [0o/0o/90o/90o]s. Experimental results show that failure mode and bearing strength are closely related to by stacking sequence of plates, geometrical parameters, and bold tension. An increase in bolt pretension positively affected failure behaviour of bolted joints.
Keywords: Bearing strength, Bolted composites, Composite
plates, Failure analysis, Failure mode
Indian
Journal of Engineering & Materials Sciences
Vol. 16, April 2009, pp. 86-92
Neuro-fuzzy modeling of hot extrusion process
Rahul Swarup Sharma,
Vikas Upadhyay & K Hans Raj
Agile manufacturing systems require models that can predict in real time the effect of various process parameters of a production process. Hot extrusion is a commonly used production process in forging industry. The relationship between the process variables (input), viz., die-velocity, temperature of billet, die angle and co-efficient of friction of a given material and extrusion force (output) required to extrude a shaft is very complex and is amenable to neuro-fuzzy approach. In this paper, a soft computing approach, i.e., neuro-fuzzy technique is used in modeling hot extrusion process to predict the punch force required to extrude a transmission shaft from ck-45 steel billet. The neuro-fuzzy model has been created out of training data obtained from the finite element (FE) simulation and correlates well with the FE results. This work has considerable implications in selection and control of process variables in real time and ability to achieve energy and material savings, quality improvement and development of homogeneous properties throughout the component and is a step towards agile manufacturing. The close agreement of the values of the final extrusion force obtained by the NF model and the FE simulation clearly indicates that the model can be used for predicting the extrusion force in the range of parameters under consideration in real-time without having to perform any extensive and costly computations. This technique opens new avenues of parameter estimation, optimization and on-line control of complex agile manufacturing systems.
Keywords: Neuro-fuzzy, FEM, Hot extrusion, Agile manufacturing.
Indian
Journal of Engineering & Materials Sciences
Vol.
16, April 2009, pp. 93-99
Rheological properties of
fiber reinforced asphalt binders
Qunshan Ye & Shaopeng Wu
Cellulose fiber, polyester fiber and mineral fiber are
employed as additives to prepare fiber reinforced asphalt binders in this
paper, with a concentration ranging from 0 to 1.0 %. Viscosity test, dynamic shear test
and creep test are conducted to investigate the rheological characteristics of
fiber reinforced asphalt binders. Experimental results indicate that the
viscosity
of fiber reinforced asphalt binders is increased by the addition of fibers,
especially when the fiber concentration is up to 0.5 % by mass of asphalt binder.
Complex shear modulus of fiber reinforced asphalt binders are
increased, which indicate that the stiffness of asphalt binders can be enhanced
by the use of fiber additives. The elastic part of viscoelastic behaviours
of asphalt binders are enhanced by the addition of fibers, which result in the reduction of the phase
angle. The master curves of complex shear modulus of fiber reinforced asphalt binders are determined
based on nonlinear least square regression according to the time-temperature
superposition theory at a control temperature (
Keywords: Asphalt binder; Fiber reinforced; Viscosity;
Viscoelastic property; Permanent deformation
Indian
Journal of Engineering & Materials Sciences
Vol.
16, April 2009, pp. 100-110
Influence of size
strength relation in modeling the behaviour of quasi-brittle materials
G Sankarasubramanian &
Modeling the behaviour of quasibrittle materials (concrete, rock, fiber composites, ceramics, etc.) is a challenging task for engineers. A comprehensive approach and methodology are required for the fracture mechanics problems of quasibrittle materials. In quasi brittle materials, the fracture process zone ahead of the crack tip is not negligible compared to the characteristic cross-sectional dimension of the specimen. Influence of strain softening zones due to cracking must be considered. This paper illustrates the importance of size effect and its salient features in the field of fracture mechanics. According to Bazant Size effect law1, the asymptotic deviation of nominal strength with respect to structural size varies from strength criteria for small size specimen to linear elastic fracture mechanics (LEFM) for large size specimen. The salient characteristics of Weibull’s statistical weak link theory and nonlocal damage theory for modeling are explained. Influence of size effect on modulus of rupture, brittleness number and rate of loading are illustrated. Salient features of crack band model, microplane model and their applications have also been summarized. Recent trends in developing virtual internal pair bond model for quasibrittle materials are also included. These concepts are essential for carrying out analytical investigations and development of design guidelines. Relatively large fracture process zone present in concrete enhances the need for extensive research in experimental methods, appropriate physical process and numerical techniques to simulate the fracture behaviour of quasibrittle materials. A summary of various models for quasibrittle materials using fracture mechanics is also presented.
Keywords: Size
effect, Nonlocal theory, Brittleness number, Fracture mechanics, Crack band
model, Microplane model, Virtual internal pair bond model
Indian
Journal of Engineering & Materials Sciences
Vol.
16, April 2009, pp. 111-115
High temperature oxidation and wear behaviour of powder metallurgically developed Ni-Cr-W-Al-Ti-MoS2 composite
Maoquan Xue
Nickel-chromium matrix
composites reinforced with tungsten, aluminum, titanium and molybdenum
disulfides are developed by a powder metallurgy method. The high temperature
oxidation properties, the friction and wear behaviour of the composites under
dry sliding condition are investigated using the pin-on-disc. The oxidation
behaviour of composite is studied by scanning electron microscopy (SEM), the
worn surfaces and worn chips are observed by X-ray diffraction (XRD) and
optical microscope. The results show that the kinetic curves of oxidation
for composite obey the parabolic law, the oxide scales consist of Cr2O3
and NiCr2O4. Both
the friction coefficient and wear rate of composites decrease with the increase
of temperature before 400°C, but the wear rate is the highest at 600°C. The
oxidative wear is the main wear mechanism for the composites.
Keywords: Molybdenum disulfides, Ni-Cr matrix composite,
Oxidation, Wear behaviour
Indian
Journal of Engineering & Materials Sciences
Vol.
16, April 2009, pp. 116-122
An experimental investigation into
the machinability of
Ihsan Korkut,
Kadir Yavuz & Yakup
Turgut
In this study, machining tests of the bearing necks of
crank shafts produced from
Keywords: Ductile iron (DI),
Indian
Journal of Engineering & Materials Sciences
Vol.
16, April 2009, pp. 123-127
Size dependent modifications in the physical properties of chemical solution deposition and pulsed laser deposition grown La0.7Ca0.3MnO3 manganite thin films: A comparative study
J H Markna, P S Vachhani, N A Shah,
J John, D
Grain-size dependence of electronic transport and
magnetoresistance (MR) properties of nanostructured La0.7Ca0.3MnO3
(LCMO) manganite thin films grown using pulsed laser deposition (PLD) and
chemical solution deposition (CSD) have been compared in the context of the
grain size, surface and strain modification due to the different synthesis
techniques used as well as due to substrate induced magnetic anisotropy. CSD
grown LCMO thin films shows the grain size ~70 nm while grain size ~150 nm is
exhibited by PLD grown films resulting in an appreciable change in the strain
and low temperature magnetoresistance (LTMR). In CSD grown film, nanostructured
grains exhibit sharp magnetic orientation in the absence of strain resulting in
the observation of large maximum TCR value ~10.1% K-1 at 235 K as
compared to PLD grown film (TCR value ~2.7% K-1 at 194 K). Epitaxial
thin films grown by the CSD technique are strain free and possess
nanostructured grains size resulting into better physical properties as
compared to PLD grown LCMO films.
Indian
Journal of Engineering & Materials Sciences
Vol.
16, April 2009, pp. 128-132
Study of surface morphology in DC and pulse plating of silver alloy
C Shanthi,
The objective of this work is to make a comparative study of
dc and pulse plating of silver on silver alloy. The dc and pulsed electro
deposition of silver on silver alloy is analyzed from an alkaline cyanide bath
with brightener. Pulse duty cycles of 20 to 80%, at frequencies 10, 25, 50 and
100 Hz with peak current densities of 3.21, 3.75 and 4.55 A/dm2 are
employed. The influences of peak current density on the thickness and current
efficiency of the plating process are studied. The surface morphology is characterized
by SEM and XRD. Less porosity and fine grains are formed by pulse plating
compared to that formed by dc plating.
Keywords: DC plating,
Pulse plating, Silver, Duty cycle, Frequency, Current efficiency
Indian
Journal of Engineering & Materials Sciences
Vol.
16, April 2009, pp. 133-139
Synthesis, characterization, curing and thermal studies of phosphorylated epoxy resins
Geeta Durga, Darshan Singh, Parveen Kukreja & A K Narula
Phosphorous containing two epoxies tris (glycidyloxy) phosphine oxide (TGPO) and tris (glycidyloxy) phosphine (TGP) are synthesized and their structure are characterized with the help of FTIR, 1HNMR, 13CNMR, and 31PNMR spectroscopy. Synthesized TGPO/TGP is blended with DGEBA, which after curing with diamine curing agents, viz., 1,4-phenylene diamine (P), 3,4’-oxydianiline (O), 4,4’-diaminodiphenyl sulphide (DS), and 1,5-diamino naphthalene (N) resulted in several phosophorylated epoxy polymers. Curing reactions and reactivities of polymers are studied via DSC, which revealed that TGP is relatively more reactive towards diamine curing agent than TGPO. Further, among the diamines phenylene diamine (P) is most reactive curing agent towards both the epoxies as compared to other diamines. Thermal gravimetric analysis (TGA) was used to study the thermal behaviour and weight loss behaviour of cured epoxy resin. The phosphorous containing epoxy resin shows lower weight loss temperature and higher char yield (~23-36) and LOI (~27-32) values than that of Bisphenol-A based epoxy resin (char yield~10-12 & LOI~21-22), which confirms the effectiveness of phosphorylated epoxy resins as flame retardant.
Keywords: Phosphorylated epoxy, Curing,
Thermal stability, Flame retardancy, Diamine.