Elastic stress analysis of rotating converging conical disks subjected to thermal load and having variable density along the radius (original) (raw)
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Thermo-mechanical analysis of rotating disks with non-uniform thickness and material properties
International Journal of Pressure Vessels and Piping, 2012
Non-uniform material property Variable material properties method Thermo-mechanical loading a b s t r a c t Theoretical and numerical analyses of rotating disks with non-uniform thickness and material properties subjected to thermo-mechanical loadings have been carried out by variable material properties (VMP), RungeeKutta's (RK) and finite element (FE) methods. The material is assumed to be elastic-linear hardening. A power form function is used to describe the temperature gradient with the higher temperature at outer surface. Von-Mises theory has been used as failure criterion. The effects of geometry, material and thermal loading parameters as well as boundary conditions on radial, hoop and equivalent stress distributions which have not been studied in much detail in previous works have been investigated. Good agreement between the results obtained from the three proposed methods is observed. It has also been observed a coarser mesh can be used in RK. Compared with previous works published by authors using variable iteration method, Adomian method, and Homotopy analysis method, VMP was found to be much easier for computer implementation and required less CPU time and computer memory and hardware.
Steady thermal stresses in a rotating disc with shaft having density variation parameter subjected to thermal load have been derived by using Seth's transition theory. Neither the yields criterion nor the associated flow rule is assumed here. Results are depicted graphically. It has been seen that compressible material required higher percentage increased angular speed to become fully-plastic as compare to rotating disc made of incompressible material. Circumferential stresses are maximal at the outer surface of the rotating disc. With the introduction of thermal effect it decreases the value of radial and circumferential stresses at inner and outer surface for fully-plastic state.
Temperature and thickness effects on thermal and mechanical stresses of rotating FG-disks
Journal of Mechanical Science and Technology, 2011
In the present paper, radial and hoop thermal and mechanical stress analysis of a rotating disk made of functionally graded material (FGM) with variable thickness is carried out by using finite element method (FEM). To model the disk by FEM, one-dimensional two-degree elements with three nodes are used. It is assumed that the material properties, such as elastic modulus, Poisson’s ratio and thermal expansion coefficient, are considered to vary using a power law function in the radial direction. The geometrical and boundary conditions are in the shape of two models including thermal stress (model-A) and mechanical stress (model-B). In model-A there exists no pressure in both external and internal layers, and there is a temperature distribution considered as a second order function in the radial direction of the rotating disk. In this case, the temperature dependency of the material properties is considered and a hyperbolic type is assumed for the geometry of the disk. In model-B, there is a constant pressure only on the internal layer and a pressure on the internal layer of the disk without temperature distribution but with different types of surface profiles. Furthermore, the displacements and stresses for various power law indices (N) and angular velocities are calculated and compared to other results in the literature. The effect of varying thicknesses and dependency of material properties on temperature distribution is investigated.
Rotating discs with variable thickness and nonhomogeneous material properties are frequently used in industrial applications. The nonhomogenity of material properties is often caused by temperature change throughout the disc. The governing differential equation presenting this problem contains many variable coefficients so that no possible analytical closed form solution for this problem. Many numerical approaches have been proposed to obtain the solution. However, in this study the Finite Element Method (FEM), which presents a powerful tool for solving such a problem, is used. Thus, a turbine disc modeled by using ax symmetric finite elements was analyzed. But, in order to avoid inaccuracy of the stress calculation quite fine meshing is implemented. The analysis showed that maximum displacement occurs at the boundary of the disc, either at the outer or inner boundary, depending on the loadings. The maximum radial stress occurs at an area in the middle of the disc which has the smallest thickness. In this study, rotational blade load was shown to give the largest contribution to the total displacement and stress. Also, the radial displacement and stress in a disc with variable thickness are found to be affected by the contour of the thickness variation. In general, the results obtained show excellent agreement with the published works.
Applied Mechanics and Materials, 2012
In this paper, a new solution is presented for one-dimensional steady-state mechanical and thermal stresses in a FG rotating hollow disk and cylinder. The material properties for FG are expressed as nonlinear exponential functions through the radius and Poisson’s ratio is taken to be constant. The temperature distribution is derived from first law of thermodynamics by solving energy equation, with a general thermal and mechanical boundary conditions on the inside and outside surfaces. Heat conduction and Navier equations are solved analytically by choosing elliptic cylinder coordinates system and the results are shown for displacement and stress components along the radial direction.
Structural Analysis in Designing Conical Discs of Rotation
2005
This study analyzes stress concentrations in symmetric and conical discs containing lateral holes and a 300mm external diameter, which goes round their own axis on a constant speed of 800 rpm. This value was taken as limit speed since it is capable of producing stresse lower then the elastic limits on over the piece for both normal and shear components. In order to allow a broader view of the results, conical discs with inclinations ranging from Oo to 45o were used, each of them with lateral holes varying in diameter from 15mm to 45m, totalizing 60 samples. The work aimed at understanding the correlation between disc inclination variation and stress concentration near lateral holes as well as the correlation between variation in lateral diameter and stress concentration near those holes. For such, models in a program of finite elements were designed and the results obtained from such models processed through analysis of statistical sensitivity. The results produced very clear conclu...
Scientific Technical Review, 2015
It has been observed that thermal effects increase the value of angular speed required to yield at the internal surface for incompressible/compressible materials. Radial stresses have a maximum value at the internal surface of the rotating disc made of incompressible materials as compared to compressible materials. With the introduction of thermal effects, radial as well as circumferential stresses must be decreased in the absence of mechanical load but when mechanical load is applied, radial as well as circumferential stresses must be increased at the internal surface of a rotating disc with a shaft. A rotating disc is likely to fracture at the bore of the radius.
Journal of Solid Mechanics, 2017
In this paper, thermo-elastic analysis of a rotating thick truncated conical shell subjected to the temperature gradient, internal pressure and external pressure is presented. Given the existence of shear stress in the conical shell due to thickness change along the axial direction, the governing equations are obtained based on first-order shear deformation theory (FSDT). These equations are solved by using multi-layer method (MLM). The model has been verified with the results of finite element method (FEM). Finally, some numerical results are presented to study the effects of thermal and mechanical loading, geometry parameters of truncated conical shell.
Using disk form multilayers, an elastic analysis is presented for determination of displacements and stresses of rotating thick truncated conical shells. The cone is divided into disk layers form with their thickness corresponding to the thickness of the cone. Due to the existence of shear stress in the truncated cone, the equations governing disk layers are obtained based on first shear deformation theory (FSDT). These equations are in the form of a set of general differential equations. Given that the truncated cone is divided into n disks, n sets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. The results obtained have been compared with those obtained through the analytical solution and the numerical solution.