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R Gnanamoorthy
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R Gnanamoorthy
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R Gnanamoorthy
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Gnanamoorthy, Rajappa
Gnanamoorthy, R.
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60 results
Now showing 1 - 10 of 60
- PublicationFretting wear studies on uncoated, plasma nitrided and laser nitrided biomedical titanium alloys(15-02-2007)
;Vadiraj, Aravind; Fretting wear resistance of uncoated and surface modified biomedical titanium alloys (Ti-6Al-7Nb) in air and Ringer fluid has been investigated in the present work. Laser nitrided specimen has shown superior performance with minimum surface damage and wear rate (<0.1 × 10-6 mm3/Nm) despite high friction coefficient in air (0.6) compared to uncoated and plasma nitrided (>12 × 10-6 mm3/Nm) specimens. This is due to presence of TiN dendrites (60-80%) in the laser nitrided layer. Plasma nitrided surface is relatively softer and hence wear rates and surface damage are comparable with uncoated alloys. Friction coefficient is high for uncoated (0.8) and plasma nitrided alloys (0.6) in air as well as Ringer fluid. Fretting induced electrochemical dissolution is responsible for higher wear rates in uncoated and plasma nitrided specimens. The fretting damage resistance is primarily governed by relative hardness and modified layer thickness of the mating components. © 2006 Elsevier B.V. All rights reserved. - PublicationEffect of oil jet peening duration on surface modification and fatigue behavior of medium carbon steel, AISI 1040(15-05-2007)
;Grinspan, A. SahayaIntroduction of compressive residual stress on the surface of dynamically loaded structural members improves the fatigue life. Oil jet peening is a new surface modification technique that can be potentially applied to introduce compressive residual stresses. Effect of oil jet peening on the surface modification and fatigue behavior of medium carbon steel, AISI 1040, is reported. The compressive residual stress on the surface of oil jet peened specimen was in the order of 332 MPa and the depth of compressive stress induced was about 50 μm. The surface hardness increased due to the oil jet peening. Oil jet peening improved the fatigue strength under cantilever-bending conditions to about 19% compared to unpeened specimens. © 2006 Elsevier B.V. All rights reserved. - PublicationDevelopment of a fretting wear test rig and preliminary studies for understanding the fretting wear properties of steels(01-01-2006)
;Ramesh, R.Rolling element bearings experience fretting wear type of failures due to small relative oscillatory motion existing between races and rolling elements of the bearing. Small oscillatory motion between contacting surfaces that occur due to overall machine or system vibration and unexpected loads in service causes accumulation of wear debris in the contact zone and accelerate the wear process. A fretting wear test rig is designed and developed in the laboratory for understanding the fretting wear behavior of bearing materials. The test rig is designed for testing at slip amplitudes ranging from 20 to 200 μm and test frequencies ranging from 1 to 30 Hz. Preliminary studies for understanding the fretting wear characteristics were conducted on hardened and tempered bearing steel, En31 and widely employed hardened and tempered structural steel, En24 at various normal loads. Coefficient of friction during fretting tests was high during the initial stages of fretting tests and reached a steady state. The coefficient of friction depends on the normal load. Wear scar morphology reveals the nature of contact exhibited by the fretting contacts. © 2004 Elsevier Ltd. All rights reserved. - PublicationStudy of damage mechanisms and failure analysis of sintered and hardened steels under rolling-sliding contact conditions(15-02-2007)
;Govindarajan, N.Due to continual improvements of the powder material processing, it is possible for powder metal alloys to compete even in some of the most demanding applications. The main lure of powder metallurgy (PM) components amongst the several challenging mass production methods plays an imperative role, as saving material, energy and also provides good fatigue properties, which are equally good and substitute for the conventional methods. The investigation on the lubricated rolling-sliding contact fatigue damage mechanisms in sintered and hardened steel (FLC 4608-110HT) containing combination of closed and interconnected pores has been carried out. Rolling-sliding contact conditions are simulated in twin disc type experimental set up for various contact pressure and slide/roll ratio. The damaged surface of sintered and hardened steel is examined under image analyzer for different sliding conditions. It is observed that the peel of material and surface crack opening is seen for the higher slide/roll ratio. Wear debris analysis is also carried out by dual-ferrograph analyzer for sintered and wrought steels for comparison study. The characteristics of wear morphology and the size, shape and concentration of worn particles are also analysed for different sliding contact conditions. © 2006 Elsevier B.V. All rights reserved. - PublicationPerformance and failure analysis of injection molded carbon reinforced nylon gears(01-01-2004)
;Senthilvelan, S.Reinforced polymers offer superior strength and modulus required in many load-bearing applications. Reinforced thermoplastic polymer gears are used in motion as well as power transmission applications. The performance of reinforced polymer gears needs to be thoroughly understood for widening their application. This paper describes results of the ongoing research on polymer composite gear performance. Unreinforced and 20% short carbon fiber reinforced Nylon granules were used for the development of gears using injection-molding process. Gear tests were conducted in a power absorption type gear test rig. Gears were tested at a constant rotational speed of 1000 rpm and at various torque levels up to 3 Nm. Test results showed the superior fatigue strength of carbon reinforced Nylon gears compared with the unreinforced Nylon gears. Improved thermal resistance, high strength and modulus contributed to the superior fatigue performance of carbon reinforced Nylon gear. Failed and worn out surfaces were observed using optical and scanning electron microscope. Three major gear failure modes were observed; excessive wear, severe deformation and tooth fracture. Fiber orientation, presence of fiber particles between contact surfaces and poor surface finish affects the wear resistance of carbon-reinforced gear. - PublicationRolling contact fatigue behaviour of carbonitrided and nitrocarburised sintered steels(01-12-2004)
; Krishnakumar, J.Sintered gears and bearings find increasing application in many automotive and other engineering industries because of many technical and economical advantages. The poor mechanical and tribological properties of sintered materials limit their application to light duty applications. Failure of gears and bearings, in general, are due to surface deterioration leading to increased sound and vibration of overall machinery. Improvement of surface properties of gears and bearings improves the overall performance of components. Results of the rolling contact fatigue studies conducted on the sintered steels subjected to different surface treatments are discussed. Experiments were conducted in the twin disc type rolling contact fatigue test rig at different contact stress levels. Contact stress vs. number of cycles for failure data was generated for the nitrocarburised and carbonitrided sintered and hardened steels. Nitrocarburised sintered steels showed superior contact fatigue behaviour compared to the carbonitrided materials. The endurance limit strength under contact fatigue conditions is significantly higher for the nitrocarburised materials. All the specimens failed by surface peeling and pitting type of failures. Surface peeling was the severe form of surface failure encountered in the sintered rollers. Significant plastic deformation was also observed. Copyright © 2004 by Society for Advancement of Heat Treatment & Surface Engineering (SAHTSE). - PublicationEffect of nanoclay reinforcement on tensile and tribo behaviour of Nylon 6(01-06-2005)
;Srinath, G.Polymer nanocomposites are particle-filled polymers in which at least one dimension of the dispersed particles is in the nanometer range. Dispersing nanosize particles in a polymer matrix induces superior mechanical properties compared to traditional macro fillers. Nanolevel reinforcement also affects the tribological properties and needs to be clearly understood before using in practical applications. Friction and wear characteristics of Nylon 6 nanocomposites under dry sliding conditions are reported in this paper. Nylon 6 with 5% organoclay was prepared by melt intercalation technique. The tensile behaviour is evaluated according to ASTM standards. A pin-on-disc type tribometer is used for evaluating the friction and wear behaviour. It is found that the Nylon 6 nanocomposites have superior tribological properties than unfilled polymer. Formation of uniform tenacious transfer layer by Nylon 6 nanocomposite on the counterface contributes to the reduction in coefficient of friction and specific wear rate. Nylon Nancomposites exhibited high wear resistance compared with the neat Nylon. © 2005 Springer Science + Business Media, Inc. - PublicationMicrostructure, strength and tribological behavior of Fe-C-Cu-Ni sintered steels prepared with MoS2 addition(01-06-2007)
;Dhanasekaran, S.Powder metal processing permits development of new composites with specific properties required for demanding applications. Complex shaped machine elements like gears and bearings are made of powder metallurgy technique economically. In many applications these machine elements operate under unlubricated conditions and there is a need for materials with good friction and wear characteristics, strength and modulus. In the present study, Fe-C-Cu-Ni alloys with solid lubricant, MoS2, were developed using a simple single stage compaction and sintering. The microstructure, strength, hardness and tribo behavior of the composites were evaluated. The friction and wear characteristics were evaluated using pin-on-disc type tribo test machine. Addition of solid lubricant improved the compressibility and thereby the density of the compacts. Presence of the secondary sulphide phases in the as-sintered compacts improves the hardness and strength. The coefficient of friction and wear loss decreased with addition of MoS2. A simple wear model is proposed to predict the wear loss in these composites. The model predicts wear loss values that are in agreement with the experimental data. © Springer Science+Business Media, LLC 2007. - PublicationEvaluation of activation energy for dynamic strain aging process in 316L(N)/316(N) SS weld joints(01-01-2008)
;Shanmugavel, M. ;Nandagopal, M. ;Sandhya, R. ;Sankara Rao, K. BhanuType 316 L(N) Stainless Steel (SS) is being currently used as a structural material for various components of Prototype Fast Breeder Reactor (PFBR). The possibility of using 316 L(N) electrodes for fabrication of 316 L(N) welding joints is being critically examined. This paper discusses about the evaluation of activation energy for Dynamic Strain Aging (DSA) process in 316L(N)/316(N) SS Weld Joints. The Gas Tungsten Arc Welding (GTAW) process was used for the root pass and Gas Metal Arc Welding (GMAW) process was used for the remaining passes. Tensile tests have been conducted in the wide temperature range from room temperature to 1023 K at a strain rate of 3 × 10-3 s -1. Yield stress showed a continuous decrease with increasing temperature, with a plateau being observed between 823 and 923 K. A minima in elongation was also observed in this temperature range. These two properties being manifestations of dynamic strain aging, further tests at different strain rates (3 × 10-5 s-1 to 3 × 10 2 s-1) were conducted in this temperature range. Detailed analyses of the results were carried out and the solute responsible for dynamic strain aging was identified to be substitutional chromium. Post test analysis of fracture surfaces and deformation substructures were correlated with the changes in tensile properties at different testing temperatures. - PublicationAbrasive wear behavior of sintered steels prepared with MoS2 addition(28-02-2007)
;Dhanasekaran, S.Sintered steels containing molybdenum di sulphide powders were developed for application as bearings, gears, connecting rods, etc. Abrasive wear characteristics of these materials are investigated as the machine elements also need to have a good abrasive wear resistance. Materials with base composition Fe-C-Cu and Fe-C-Cu-Ni containing varying levels of MoS2 were developed from elemental powders. Compressive strength, hardness and density are influenced by the addition of MoS2. Abrasive wear tests were conducted by sliding against the SiC abrasive sheet at room temperature. MoS2 added material exhibited a high coefficient of friction and good wear resistance compared to the base composition. The artificial neural network model developed predicts the wear volumes, which are in agreement with the experimentally measured data. © 2006 Elsevier B.V. All rights reserved.