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Thermoelastic Analysis of Thick-walled FG Cylinders Using the Strain Gradient Elasticity

Sadeghi, Hossein | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40588 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Naghdabadi, Reza
  7. Abstract:
  8. There are experimental observations that show material response in micro-scale is dependent on some other parameters rather than Lame parameters. Strain gradient elasticity has been recently developed to take into account this characteristic of materials response. In strain gradient elasticity, characteristic length parameters enter the constitutive equations through the elastic strain energy density function. The elastic strain energy density function is assumed to be a function of the gradient of strain tensor in addition to the strain tensor. In this way, new material constant (characteristic length parameters) are introduced and entered into the constitutive equations. In recent years, FG materials, in which mechanical properties are dependent on position, have attracted many researchers because of their unique features. Special characteristics of FG materials make them a potential candidate for many applications such as thick-walled cylinders. In this project, strain gradient elasticity/thermo-elasticity formulation of homogenous/FG micro-cylinders subjected to thermal and mechanical loadings is presented. Power law of distribution is assumed for variation of material properties in radial direction. The kinetic, constitutive and governing equations of micro-cylinders are presented. The governing equations are fourth order ODE and analytical or numerical methods are presented to analyze the strain gradient elasticity/thermo-elasticity of homogenous/FG micro-cylinders. Results show that the intrinsic length parameter has a significant effect on the stress distribution of FG micro-cylinders and increasing the intrinsic length parameter reduces the maximum radial and hoop stresses, rapidly. It is shown that increasing c from 0 to maximum radial stress reduces about 64%. Also, it is shown that the power index m does not have much effect on the results whereas the power indices n and p have significant effect on the results. In addition, it is shown that by increasing n the maximum radial and hoop stresses increases, rapidly. Also, it is noted that increasing p, increases the maximum radial displacement and hoop stresses whereas it has no effect on the maximum radial stress.

  9. Keywords:
  10. Strain Gradient Elasticity ; Thermoelasticity ; Charachteristic Length ; Functionally Graded Materials (FGM) ; Microcylinder

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