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Search Results: 1 - 10 of 1642 matches for " Biplab Chatterjee "
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A Finite Element Study of Elastic-Plastic Hemispherical Contact Behavior against a Rigid Flat under Varying Modulus of Elasticity and Sphere Radius  [PDF]
Prasanta Sahoo, Biplab Chatterjee
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.24030
Abstract: The present study considers a finite element analysis of elastic-plastic axi-symmetric hemispherical contact for a frictionless deformable sphere pressed by a rigid flat. The material of the sphere is modeled as elastic perfectly plastic. Analysis is carried out to study the effect of varying modulus of elasticity and sphere radius in wide range of dimensionless interference until the inception of plasticity as well as in plastic range. Results are compared with previous elastic-plastic models. It is found that materials with Young’s modulus to yield strength (E/Y) ratio less than and greater than 300 show strikingly different contact phenomena. The dependency of E on dimensionless interference at which the plastic region fully covers the surface is observed. However with different radius, finite element study exhibits similar elastic-plastic phenomena.
Effect of Strain Hardening on Elastic-Plastic Contact of a Deformable Sphere against a Rigid Flat under Full Stick Contact Condition
Biplab Chatterjee,Prasanta Sahoo
Advances in Tribology , 2012, DOI: 10.1155/2012/472794
Abstract: The present study considers the effect of strain hardening on elastic-plastic contact of a deformable sphere with a rigid flat under full stick contact condition using commercial finite element software ANSYS. Different values of tangent modulus are considered to study the effect of strain hardening. It is found that under a full stick contact condition, strain hardening greatly influences the contact parameters. Comparison has also been made between perfect slip and full stick contact conditions. It is observed that the contact conditions have negligible effect on contact parameters. Studies on isotropic and kinematic hardening models reveal that the material with isotropic hardening has the higher load carrying capacity than that of kinematic hardening particularly for higher strain hardening. 1. Introduction Surface interactions are dependent on the contacting materials and the shape of the contacting surfaces. The shape of the surface of an engineering material is a function of both its production process and the nature of the parent material. When studied carefully on a very fine scale, all solid surfaces are found to be rough. So when two such surfaces are pressed together under loading, only the peaks or the asperities of the surface are in contact and the real area of contact is only a fraction of the apparent area of contact. In such conditions the pressure in those contact spots are high. Accurate calculation of contact area and contact load are of immense importance in the field of tribology and lead to an improved understanding of friction, wear, and thermal and electrical conductance between surfaces. However, it is a difficult task as rough surfaces consist of asperities having different radius and height. The problem is simplified when Hertz [1] provides the contact analysis of two elastic solids with geometries defined by quadratic surfaces. From then, the assumption of surfaces having asperities of spherical shape is adopted to simplify the contact problems. Greenwood and Williamson [2] used the Hertz theory and proposed an asperity-based elastic model where asperity heights follow a Gaussian distribution. Hertz assumed frictionless surfaces and his theory is restricted for perfectly elastic solids. Later on, researchers have attempted to investigate the effect of material properties beyond the Hertz restriction and the elastic plastic contact of a sphere with a flat became a fundamental problem in contact mechanics. The plastic model introduced by Abbot and Firestone [3], neglects volume conservation of the plastically deformed sphere.
Effect of Strain Hardening on Unloading of a Deformable Sphere Loaded against a Rigid Flat – A Finite Element Study
Biplab Chatterjee,Prasanta Sahoo
International Journal of Engineering and Technology , 2010,
Abstract: The present study considers an elastic-plastic contact analysis during loading-unloading of a deformable sphere with a rigid flat using finite element method. The effect of strain hardening on the contact behavior of a nonadhesive frictionless elastic-plastic contact is analyzed using commercial finite element software ANSYS. To study the strain hardening effect different values of tangentmodulus are considered by varying the hardening parameter. The range of hardening parameter is chosen in such a way that most of the practical materials belong in this range. The effect of strain hardening is explained through the results of simulations and compared with elastic perfectly plastic models as well as available loadingunloading models. Analysis has been carried out for deformations up to 200 times the critical interference. It is found that the contact parameters during loadingunloading are not of uniform nature within the range of hardening parameters used in this study. Increased strain hardening results in less residual strain and offer less resistance to full recovery of the original spherical shape. Multiple loading-unloading is also done for two extreme cases of hardening parameters to study the fluctuation of dimensionless interference during subsequent cycles. The contact parameters are found identical with first cycle of loading-unloading.
Finite-Element-Based Multiple Normal Loading-Unloading of an Elastic-Plastic Spherical Stick Contact
Biplab Chatterjee,Prasanta Sahoo
ISRN Tribology , 2013, DOI: 10.5402/2013/871634
Abstract: The repeated normal elastic plastic contact problem of a deformable sphere against a rigid flat under full stick contact condition is investigated with a commercial finite element software ANSYS. Emphasis is placed on the effect of strain hardening and hardening model with the maximum interference of load ranging from elastic to fully plastic, which has not yet been reported. Different values of tangent modulus coupled with isotropic and kinematic hardening models are considered to study their influence on contact parameters. Up to ten normal loading-unloading cycles are applied with a maximum interference of 200 times the interference required to initiate yielding. Results for the variation of mean contact pressure, contact load, residual interference, and contact area with the increasing number of loading unloading cycles at high hardening parameter as well as for low tangent modulus with two different hardening models are presented. Results are compared with available finite element simulations and in situ results reported in the literature. It is found that small variation of tangent modulus results in same shakedown behavior and similar interfacial parameters in repeated loading-unloading with both the hardening rules. However at high tangent modulus, the strain hardening and hardening rules have strong influence on contact parameters. 1. Introduction Multiple repeated normal loading unloading is common in engineering applications. Several researchers have identified the use of repeated normal loading unloading in various fields of engineering applications such as contact resistance in MEMS micro switches [1, 2], head-disk interaction in magnetic storage systems [3], ultrasonic interfacial stiffness measurement [4], stamping mechanism, and in rolling element bearings, gears, cams, and so forth. Earlier the problems of multiple loading-unloading were solved assuming a specific pressure distribution. The contact region related to the analysis of Kapoor et al. [5], Williams et al. [6] did not exceed greatly the elastic limit; hence they assumed Hertzian [7] contact. Merwin and Johnson [8], Kulkarni et al. [9], Bhargava et al. [10, 11] used Hertzian or modified Herzian pressure distribution even for elastic plastic contacts. In most engineering applications, the contact deformation occurred in elastic plastic as well as in plastic region. The arbitrary selection of pressure distribution where the plasticity effects are dominant eventually would provide inaccurate solution. Beyond the Hertzian assumption of nonadhesive frictionless contact within
Finite Element based Elastic-Plastic Contact Behaviour of a Sphere against a Rigid Flat – Effect of Strain Hardening
Prasanta Sahoo,,Biplab Chatterjee,,Dipankar Adhikary
International Journal of Engineering and Technology , 2010,
Abstract: The present study considers an elastic-plastic contactanalysis of a deformable sphere with a rigid flat using finiteelement method. The effect of strain hardening on the contactbehaviour of a non-adhesive frictionless elastic-plastic contact isanalyzed using commercial finite element software ANSYS. Tostudy the strain hardening effect we have taken different valuesof tangent modulus. The result of strain hardening effect clearlyshows that a generalized solution can not be applicable for allkind of materials as the effect of strain hardening differentlyinfluenced the contact parameters. With the increase in the valueof hardening parameter this effect also increases. For highervalue of hardening parameter the effect of strain hardening issevere on contact parameters. With the increase in strainhardening the resistance to deformation of a material isincreased and the material becomes capable of carrying higheramount of load in a smaller contact area.
Identification of potential apicoplast associated therapeutic targets in human and animal pathogen Toxoplasma gondii ME49
Sadegh Saremy,Biplab Bhattacharjee*,Mahdi Eskandarian Boroujeni,Jhinuk Chatterjee
Bioinformation , 2011,
Abstract: Toxoplasma gondii ME49 is an obligatory intracellular apicomplexa parasite that causes toxoplasmosis in humans, domesticated and wild animals. Waterborne outbreaks of acute toxoplasmosis worldwide reinforce the transmission of Toxoplasma gondii ME49 to humans through contaminated water and may have a greater epidemiological impact than previously believed. In the quest for drug and vaccine target identification subtractive genomics involving subtraction between the host and pathogen genome has been implemented for enlisting essential pathogen specific proteins. Using this approach, our analysis on both human and Toxoplasma gondii ME49 reveals that out of 7987 protein coding sequences of the pathogen, 950 represent essential non human-homologous proteins. Subcellular localization prediction & comparative-biochemical pathway analysis of these essential proteins gives a list of apicoplast-associated proteins having unique pathogen-specific metabolic pathway. These apicoplast-associated enzymes involved in fatty acid biosynthesis pathway of Toxoplasma gondii ME49, may be used as potential drug targets, as the pathway is vital for the protozoan’s survival. Structure prediction of drug target proteins was done using fold based recognition method. Screening of the functional inhibitors against these novel targets may result in discovery of novel therapeutic compounds that can be effective against Toxoplasma gondii ME49.
HIV Infection in T-lymphocytes and Drug Induced CTL Response of a Time Delayed Model
Priti Kumar Roy,Amar Nath Chatterjee,Biplab Chattopadhyay
Lecture Notes in Engineering and Computer Science , 2010,
Abstract:
Similarities between 2D and 3D convection for large Prandtl number
Ambrish Pandey,Mahendra K. Verma,Anando G. Chatterjee,Biplab Dutta
Physics , 2014,
Abstract: Using direct numerical simulations of Rayleigh-B\'{e}nard convection (RBC), we perform a comparative study of the spectra and fluxes of energy and entropy, and the scaling of large-scale quantities for large and infinite Prandtl numbers in two (2D) and three (3D) dimensions. We observe close similarities between the 2D and 3D RBC, in particular the kinetic energy spectrum $E_u(k) \sim k^{-13/3}$, and the entropy spectrum exhibits a dual branch with a dominant $k^{-2}$ spectrum. We showed that the dominant Fourier modes in the 2D and 3D flows are very close. Consequently, the 3D RBC is quasi two-dimensional, which is the reason for the similarities between the 2D and 3D RBC for large- and infinite Prandtl numbers.
Screening for Aphid Incidence on Some Potato Germplasm in Plains of West Bengal  [PDF]
Biplab Kahar, Amitava Konar
Agricultural Sciences (AS) , 2016, DOI: 10.4236/as.2016.76036
Abstract: A field trial was conducted to study the impact of various potato germplasm against aphids, Myzus persicae (Sulzer) and Aphis gossypii Glover (Aphididae: Hemiptera) during rabi season from November to March in 2012-2013 and 2013-2014, respectively at Adisaptagram Block Seed Farm, Hooghly, West Bengal. The population of aphids was started on potato crop in between third week of December and first week of January irrespective of various germplasms, except K. Chipsona-2, where its infestation was initiated during second and third week of January. Then, their population was gradually increased to reach its critical level (ETL) during first and second week of January in most of the potato germplasm, except in K. Anand, K. Chipsona-1, K. Chipsona-2 and Sailaja, where it was crossed in between fourth week of January and first week of February. The peak population of aphids was observed during third and fourth week of February in most of the potato germplasm. It was observed that K. Ashoka, K. Badshah, K. Chandramukhi, K. Jawahar, K. Jyoti and K. Pukhraj were highly susceptible to the pests, while K. Anand and K. Sutlez were moderately susceptible but K. Chipsona-1 , K. Chipsona-2 and K. Sailaja were less susceptible or tolerant to the pests. Maximum tuber yield (t/ha) of potato was recorded in K. Badshah (36.58 - 43.92) while it was lowest in K. Chandramukhi (22.08 - 22.12).
The Style of ‘Lokaabharan’ in Indian Proverbs
Biplab Chakraborty
Folklore : Electronic Journal of Folklore , 2007,
Abstract: The changing pattern of Indian proverbs is very much reflected invarious literary creations, especially in modern Indian poetry. Proverbs are used in poetry as a mode of creative process which entails change. Indeed, it is mostly expressed in a poetic style of narration which may be termed as the style of ‘lokaabharan’. Various types of folk elements are used in the creative process and amongst such folk elements proverbs assume a very important position in the making of the style of ‘lokaabharan’.The central message of a proverb is often conveyed with a subtle touch of language use as a linguistic device. Patterns of changes in language use need to be examined with a view to measure the mode of expression of the proverb concerned. In order to understand the style of ‘lokaabharan’, we must examine how proverbs have been used as fixative factors. In this process, we need to compare and contrast the original proverbs used and their changing patterns available in the text of the poems concerned. Fixative factors are what may be called the core of folk elements used in a poem. This may be either a conscious creative effort or an unconscious artistic measure. It plays a vital role in conveying the central theme or message, whatever the case may be.
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