Browsing by Author "ESSA, Saad"
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Item ELASTIC ANALYSIS OF POLAR ORTHOTROPIC FUNCTIONALLY GRADED ROTATING ANNULAR DISKS(2015-01-30) ESSA, Saad; ARGEŞO, Ahmet HakanSemi-analytical and analytical solutions are presented for polar orthotropic annular functionally graded rotating disks by taking also thickness variation into account. The formulations are performed by referring to polar coordinate system and the material properties are assumed to vary in radial direction. The governing equation of the problems are obtained under the assumptions of plane stress and small deformations. Disks having two types of boundary conditions are considered. The first one is an annular disk having traction free inner and outer surfaces, whereas, the second has a rigid inclusion within and traction free outer surface. Semi-analytical solution is obtained by assuming that elasticity moduli and disk thickness vary according to a nonlinear function in which its shape is controlled by three parameters. Poisson’s ratios are assumed to be constant valued and the variation of density can be described by any form of continuous function. The three parametered nonlinear function is formed by combining the exponential and power forms of variation functions that are widely used in literature for describing material gradation. The analytical solution is determined by considering that the Elasticity moduli, disk thickness and density vary according to power law. Solutions are verified numerically by using a computational method which is based on nonlinear shooting method. Verification examples are given first. Then, parametric analysis that inspects the effects of the degree of orthotropy and material gradation on the elastic responses of rotating disks are presented. In the analysis, elastic limit angular velocities of the disks are evaluated according to Hosford’s criteria.