Indian Journal of

 Engineering & Materials Sciences

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VOLUME 16

NUMBER 2

APRIL 2009

CODEN : IEMSEW

 

ISSN : 0971-4588

 

  CONTENTS

 

Engineering

 

Collapse behaviour and simplified modeling of triangular cross-section columns

71

        Yucheng Liu

 

 

 

Failure analysis of composite single bolted-joints subjected to bolt pretension

79

        Murat Pakdil

 

 

 

Neuro-fuzzy modeling of hot extrusion process

86

        Rahul Swarup Sharma, Vikas Upadhyay & K Hans Raj

 

 

 

Rheological properties of fiber reinforced asphalt binders

93

        Qunshan Ye & Shaopeng Wu

 

 

 

Influence of size strength relation in modeling the behaviour of quasi-brittle

 

materials

100

        G Sankarasubramanian & S Eswari

 

 

 

Materials Science

 

High temperature oxidation and wear behaviour of powder metallurgically

 

developed Ni-Cr-W-Al-Ti-MoS2 composite

111

        Maoquan Xue

 

 

 

An experimental investigation into the machinability of GGG-70 grade

 

spheroidal graphite cast iron

116

        Ihsan Korkut, Kadir Yavuz & Yakup Turgut

 

 

 

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

123

        J H Marknaa, P S Vachhani, N A Shah, J John, D S Rana , S K Malik &

 

        D G Kuberkar

 

 

 

Study of surface morphology in DC and pulse plating of silver alloy

128

        C Shanthi, S Barathan , Rajasrisen Jaiswal & R M Arunachalam

 

 

 

Synthesis, characterization, curing and thermal studies of phosphorylated

 

epoxy resins

133

        Geeta Durga, Darshan Singh, Parveen Kukreja  & A K Narula

 

 

 

 

 

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 (20°C). It is implied that the reinforcing effects of fibers are more significant at lower frequencies. The development of creep strain curves for asphalt binders varied remarkably by the addition of fibers. The total strain during loading period and the permanent strain are reduced greatly when fibers are added, which revealed that the resistance to permanent deformation can be significantly improved for asphalt binders containing fibers.

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 & S Eswari

 

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 GGG-70 grade spheroidal graphite cast iron

Ihsan Korkut, Kadir Yavuz  & Yakup Turgut

 

 

In this study, machining tests of the bearing necks of crank shafts produced from GGG-70 grade ductile iron (DI) are carried out. Coated cemented carbide inserts are used in the machining tests. The tests are carried out at four different cutting speeds (250, 275, 300 and 325 m/min), three different feed rates (0.15, 0.25 and 0.30 mm/rev) and two different depth of cuts (0.5 mm and 2 mm). The effects of these parameters on the surface roughness and the cutting force are investigated. Increasing cutting speed is found to deteriorate the surface roughness. The best average surface roughness values are obtained at 250 m/min which is the lowest cutting speed. Main cutting forces increased with increasing feed rate and depth of cut.

Keywords: Ductile iron (DI), Cam shaft, Machinability, Cutting forces, Surface roughness

 

 

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 S Rana, S K Malik & D G Kuberkar

 

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, S Barathan, Rajasrisen Jaiswal & R M Arunachalam

 

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.