Sreyas Institute of Engineering and Technology

Hyderabad, India

Sreyas Institute of Engineering and Technology

Hyderabad, India

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Venkateshwarlu N.,Vignans Institute of Technology and Aeronautical Engineering | Akella S.,Sreyas Institute of Engineering and Technology | Reddy T.K.K.,JNTUH College of Engineering
Journal of Structural Engineering (India) | Year: 2016

Evaluation of thermal post-buckling behavior of heated slender, symmetric, linearly tapered columns, is demonstrated by using a simple intuitive formulation which requires only the mechanical equivalent of the thermal buckling, arid the tensile loads, induced in the tapered columns, respectively. Thermal buckling occurs because of the induced compressive load due to the temperature rise from the stress free temperature, when the ends of the tapered columns are constrained to move axially. When the deflections are moderately large, the axial strain-displacement relation becomes nonlinear (von-Karman type). Hence, a tensile load is induced in the column while bending, as a result of the axial boundary conditions, due to the stretching of the neutral axis. Symmetric hinged-hinged and clamped-clamped linearly symmetric tapered columns are considered in this study, so that the structural system becomes completely symmetric. Numerical results in the form of the ratios of thermal post-buckling to buckling loads, varying with the taper and central deflection ratios, obtained from the intuitive formulation, are presented for tapered columns, with the aforementioned boundary conditions. The results match well with those obtained by the Rayleigh-Ritz method, establishing the effectiveness of the intuitive formulation.


Venkateshwarlu N.,Vignans Institute of Technology and Aeronautical Engineering | Akella S.,Sreyas Institute of Engineering and Technology | Kishen Kumar Reddy T.,JNTUH College of Engineering
Journal of Structural Engineering (India) | Year: 2016

Elastic foundations, either discrete or continuous, are commonly used in many fields of civil, mechanical, aerospace, automobile and nuclear engineering structures. The commonly used continuous elastic foundation is the linear Winkler foundation that is modelled with a number of parallel elastic springs. The prediction of the structural response like static, dynamic and buckling analyses becomes simpler, if the linear Winkler foundation is used. However, if the structural deflections are high, the nonlinearity involved in the foundation stiffness has to be considered. Two types of nonlinear elastic foundation stiffness models are presented here. The first nonlinear foundation stiffness depends on the deflection and the second one depends on the square of the deflection. Analytical expressions for the thermal buckling loads of the heated hinged-hinged and clamped-clamped uniform columns resting on these nonlinear elastic foundations are derived, by using the Rayleigh-Ritz method. The numerical results presented for the thermal buckling loads, clearly show the contribution of the variousparameters existing in the nonlinear elastic foundations.


Ali Khan M.S.,M.J.C.E.T. | Suresh A.,Sreyas Institute of Engineering and Technology | Ramaiah N.S.,M.J.C.E.T.
Journal of Engineering, Design and Technology | Year: 2016

Purpose – The purpose of this paper is to evaluate the performance of the semi-active fluid damper. It is recognized that the performance of such a damper depends upon the magnetic and hydraulic circuit design. These dampers are generally used to control the vibrations in various applications in machine tools and robots. The present paper deals with the design of magneto-rheological (MR) damper. A finite element model is built to analyze and understand the performance of a 2D axi-symmetric MR damper. Various configurations of damper with modified piston ends are investigated. The input current to the coil and the piston velocity are varied to evaluate the resulting change in magnetic flux density (B), magnetic field (H), field dependent yield stress and magnetic force vectors. The simulation results of the various configurations of damper show that higher magnetic force is associated with plain piston ends. The performance of filleted piston ends is superior to that of other configurations for the same magnitude of coil current and piston velocity. Design/methodology/approach – The damper design is done based on the fact that mechanical energy required for yielding of MR fluid increases with increase in applied magnetic field intensity. In the presence of magnetic field, the MR fluid follows Bingham’s plastic flow model, given by the equation τ = η γ•+τ y (H) τ>τ y . The above equation is used to design a device which works on the basis of MR fluid. The total pressure drop in the damper is evaluated by summing the viscous component and yield stress component which is approximated as ΔP = 12ηQL/g3W + CτyL/g, where the value of the parameter, C ranges from a minimum of 2 (for ΔPτ ΔPη less than approximately 1) to a maximum of 3 (for ΔPτ/ΔPη greater than approximately 100). To calculate the change in pressure on either side of the piston within the cylinder, yield stress is required which is obtained from the graph of yield stress vs magnetic field intensity provided by Lord Corporation for MR fluid −132 DG. Findings – In this work, three different finite element models of MR damper piston are analyzed. The regression equations, contour plots and surface plots are obtained for different parameters. This study can be used as a reference for selecting the parameters for meeting different requirements. It is observed from the simulation of these models that the plain ends model gave optimum magnetic force and 2D flux lines with respect to damper input current. This is due to the fact that the plain ends model has more area when compared with that of other models. It is also observed that filleted ends model gave optimum magnetic flux density and yield stress. As there is reduced pole length in the filleted ends model, the MR fluid occupies vacant area, and hence results in increased flux density and yield shear stress. The filleted ends assist the formation of dense magnetic flux lines thereby increasing the flux density and yield stress. This implies that higher load can be carried by the filleted ends damper even with a smaller size. Originality/value – This work is carried out to manufacture different capacities of the dampers. This can be applied as vibration controls. © 2016, © Emerald Group Publishing Limited.


Sainath K.,Sreyas Institute of Engineering and Technology | Akella S.,Sreyas Institute of Engineering and Technology | Reddy T.K.K.,Jawaharlal Nehru University
Materials Today: Proceedings | Year: 2015

In almost every industry, home and every institution now a days air-conditioning, refrigeration is necessary. Whether be it a high profile mechanical company or a highly equipped computer lab. Refrigeration and cooling is necessary. Hence refrigeration and air-conditioners come into picture. There are, obviously, a lot of basic parts in the main unit used. One of the basic components is evaporator. Aluminum roll-bond evaporators provide unique design flexibility for direct cooling refrigeration systems. Roll bond evaporators deliver efficient thermal performance in a product that can be shaped to fit most applications. Whether the product requires a sample flat panel or a multi shaped evaporator, the company's engineers will collaborate with the clients closely to develop the best solution. A roll bond evaporator is also called a plate surface evaporator, which is used in domestic refrigerators. A serpentine tube is placed between two metal plates such that the plates press on to the tube and the edges of the plates are welded together. The space between the plates is filled with eutectic solution or evacuated. The eutectic solution has low freezing point, as it has good thermal conductivity when compared to air and vacuum. If eutectic solution provides a good hold up capacity, the refrigerants enter from the inlet and travel via the tube passage and finally leave the outlet. This roll bond evaporator is transfers heat effectively. © 2015 Elsevier Ltd.


Kumar A.,Thapar University | Kumar A.,Indian Institute of Chemical Technology | Kumar V.P.,Indian Institute of Chemical Technology | Srikanth A.,Indian Institute of Chemical Technology | And 2 more authors.
Catalysis Letters | Year: 2016

Au/SBA-15 nano catalysts were synthesized from four different methods, viz., homogeneous deposition-precipitation, micro-emulsion, impregnation and polyol, and their catalytic activities were investigated for the vapor phase oxidation of benzyl alcohol to benzaldehyde. The physico-chemical properties of the catalysts were characterised by XRD, TEM, BET surface area, pore size distribution, CO-chemisorption and XPS techniques. The structural data of the catalysts along with their catalytic studies indicate that the presence of very small metallic Au0 species with particle size of 7-8 nm, was responsible for the higher activity observed in the vapor phase oxidation of benzyl alcohol reaction. The title reaction, though industrially important, was used as a test reaction to investigate firstly, the influence of different preparation methods on the uniform dispersion of gold particles on the support SBA-15 and to understand the metal-support interaction in Au/SBA-15 catalysts, and secondly, to study the catalytic performance of the catalyst (Au/SBA-15) in terms of activity, selectivity and stability over a period of reaction time. The conversion of benzyl alcohol was found to increase with decrease in the size of gold particles. Smaller gold particles with higher percentage of dispersion on the support SBA-15 had a beneficial effect on the catalytic activity. Among the four methods used for the preparation of gold on SBA-15 support, the catalyst prepared by homogeneous deposition-precipitation method showed the best performance in terms of conversion, selectivity for benzaldehyde and longer catalyst life. Graphical Abstract: Vapor phase oxidation of benzyl alcohol over nano Au/SBA-15 catalysts. [Figure not available: see fulltext.] © 2015 Springer Science+Business Media New York.


Gosukonda S.,Guru Nanak Institute of Technology | Srikanth Gorti V.P.N.,Guru Nanak Institute of Technology | Baluguri S.B.,Sreyas Institute of Engineering and Technology | Sakam S.R.,Guru Nanak Institute of Technology
Procedia Engineering | Year: 2015

Particle size plays vital role in determination of heat transfer through a nano-fluid. But the chemical reaction of copper metal particle with water certainly alters the expected heat transfer rate. So the size of the nano-particle in its flow can be described by Newton's law. All the assumptions lead to a system of coupled non-linear governing partial differential equations. These equations are solved for velocity (w) and temperature (θ) using R-K 6th order with shooting method subject to the boundary conditions. The profiles of w, θ and the heat transfer rate (Nu) for various parameters are displayed. The inter particle spacing enhances the heat transfer rate due to the Brownian motion of the particles. © 2015 The Authors.


Kumar A.,Indian Institute of Chemical Technology | Kumar V.P.,Indian Institute of Chemical Technology | Vishwanathan V.,Sreyas Institute of Engineering and Technology | Chary K.V.R.,Indian Institute of Chemical Technology
Materials Research Bulletin | Year: 2015

The vapor phase oxidation of benzyl alcohol was investigated over Au/MCM-41 catalysts under aerobic conditions. The catalysts were prepared by homogeneous deposition-precipitation (HDP) method. The physico-chemical properties of the catalysts were investigated by XRD, TEM, BET surface area, CO-chemisorption, and XPS techniques. The influence of metal, nature of the support, the metal-support interactions, the catalytic activity, and stability of the Au/MCM-41 catalysts were investigated. The conversion of benzyl alcohol was increasing with decrease in the size of Au nanoparticles. Au/MCM-41 catalysts with smaller Au nanoparticles had a beneficial effect on the catalytic properties during the oxidation of benzyl alcohol. © 2014, Elsevier Ltd. All rights reserved.


Kumar A.,Indian Institute of Chemical Technology | Kumar V.P.,Indian Institute of Chemical Technology | Kumar B.P.,Indian Institute of Chemical Technology | Vishwanathan V.,Sreyas Institute of Engineering and Technology | Chary K.V.R.,Indian Institute of Chemical Technology
Catalysis Letters | Year: 2014

The vapor phase oxidation of benzyl alcohol was investigated over gold nanoparticles supported on mesoporous titanium dioxide (anatase) catalysts under aerobic conditions. The catalysts were prepared by homogeneous deposition-precipitation method using urea as the precipitating agent. The physico-chemical properties of the synthesized catalysts were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), pore size distribution (PSD), CO-chemisorption and X-ray photoelectron spectroscopy (XPS) techniques. The crystallite size of gold in Au/TiO2 catalysts was measured from XRD. The mesoporosity of TiO2 support and Au/TiO 2 catalysts were confirmed by PSD analysis. TEM results suggest that gold nanoparticles are well dispersed over mesoporous TiO2. The catalytic functionality is well substantiated with particle size measured from TEM. XPS results reveal the formation of Au(0) after chemical reduction by NaBH4. The vapor phase benzyl alcohol oxidation was used as a test reaction to investigate the influence of the metal, nature of the support, and of metal-support interactions in Au/TiO2 catalysts and also the catalytic activity and stability of the Au/TiO2 catalysts. The conversion of benzyl alcohol was found to increase with decrease in the size of gold particles. Smaller gold particles and a higher amount of small gold particles had a beneficial effect on the catalytic activity. The catalytic activity in the presence of oxygen is believed to be associated with the transport of electrons through the catalyst to the adsorbed oxygen on the surface. Graphical Abstract: [Figure not available: see fulltext.]. © 2014 Springer Science+Business Media New York.


Kumar A.,Indian Institute of Chemical Technology | Kumar V.P.,Indian Institute of Chemical Technology | Vishwanathan V.,Sreyas Institute of Engineering and Technology | Chary K.V.R.,Indian Institute of Chemical Technology
Journal of Nanoscience and Nanotechnology | Year: 2015

The Au/MCM-41 nano catalysts were synthesized from four different methods, viz., homogeneous deposition-precipitation, micro-emulsion, impregnation and polyol and their catalytic activities were tested for the vapor phase oxidation of benzyl alcohol to benzaldehyde. The physico-chemical properties of the catalysts were investigated by XRD, TEM, BET surface area, PSD, CO-chemisorption and XPS techniques. The effect of preparation methods, nature of the metal, support and the metalsupport interaction in Au/MCM-41 catalysts were studied for the title reaction. The Au/MCM-41 catalysts synthesized from HDP method has shown higher and better catalytic activity as compared to the catalysts prepared by other methods. Copyright © 2015 American Scientific Publishers All rights reserved.

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