Faculty Publications
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Item Static analysis of functionally graded beams using higher order shear deformation theory(2008) Kadoli, R.; Akhtar, K.; Ganesan, N.Displacement field based on higher order shear deformation theory is implemented to study the static behavior of functionally graded metal-ceramic (FGM) beams under ambient temperature. FGM beams with variation of volume fraction of metal or ceramic based on power law exponent are considered. Using the principle of stationary potential energy, the finite element form of static equilibrium equation for FGM beam is presented. Two stiffness matrices are thus derived so that one among them will reflect the influence of rotation of the normal and the other shear rotation. Numerical results on the transverse deflection, axial and shear stresses in a moderately thick FGM beam under uniform distributed load for clamped-clamped and simply supported boundary conditions are discussed in depth. The effect of power law exponent for various combination of metal-ceramic FGM beam on the deflection and stresses are also commented. The studies reveal that, depending on whether the loading is on the ceramic rich face or metal rich face of the beam, the static deflection and the static stresses in the beam do not remain the same. © 2007 Elsevier Inc. All rights reserved.Item Stress analysis of SUS 304 - Ceramics functionally graded beams using third order shear deformation theory(2008) Akhtar, K.; Kadoli, R.Kinematics for moderately thick rectangular beams satisfying zero shear strain on the top and bottom . surfaces is utilized to define the strain displacement relations involving the membrane, bending and higher order of displacements. Strain energy containing shear rotation term is deduced. The principle of stationary potential energy is used to obtain the static finite element equilibrium equations for the FGM (functionally graded material) beam with a uniformly distributed transverse load. FGM beams with continuous and smooth grading of metal and ceramics based on po wer law index are considered for the study. Equivalent single layer approach is followed for the evaluation of the constitutive matrix of the FGM beam. Numerical results are presented on the axialstresses and shear stresses in SUS304-Al3O3, SUS 304-ZrO2 and SUS 304-Si3N4FGM beams with clamped-clamped and simply supported boundary conditions. The effect of volume fraction of ceramic and metal on the nature of stress distribution through the thickness are investigated. The studies reveal that, the magnitude and distribution profile of static stresses in the beam depends on the power law index and also on the nature of load bearing surface, ie, whether the loading is on the ceramic rich face of the beam or metal rich face.Item Comparative analysis of steady state heat transfer in a TBC and functionally graded air cooled gas turbine blade(2010) Coomar, N.; Kadoli, R.Internal cooling passages and thermal barrier coatings (TBCs) are presently used to control metal temperatures in gas turbine blades. Functionally graded materials (FGMs), which are typically mixtures of ceramic and metal, have been proposed for use in turbine blades because they possess smooth property gradients thereby rendering them more durable under thermal loads. In the present work, a functionally graded model of an air-cooled turbine blade with airfoil geometry conforming to the NACA0012 is developed which is then used in a finite element algorithm to obtain a non-linear steady state solution to the heat equation for the blade under convection and radiation boundary conditions. The effects of external gas temperature, coolant temperature, surface emissivity changes and different average ceramic/metal content of the blade on the temperature distributions are examined. Simulations are also carried out to compare cooling effectiveness of functionally graded blades with that of blades having TBC. The results highlight the effect of including radiation in the simulation and also indicate that external gas temperature influences the blade heat transfer more strongly. It is also seen that graded blades with about 70% ceramic content can deliver better cooling effectiveness than conventional blades with TBC. © 2010 Indian Academy of Sciences.