Mathematical modeling of creep in rotating discs of composites and functionally Gradient materials

Abstract

The research work presented in this thesis deals with the study of \Mathematical Modeling of Creep in Rotating Discs of Composites and Functionally Gradient Materials". In many applications, rotating discs are exposed to elevated tem- peratures where creep deformation becomes important. From this point of view, an attempt has been made to analyze creep in rotating disc made of lightweight aluminum/aluminum alloy based composite so as to develop more reliable design codes for real life applications. In the present study, analysis has been done for isotropic/anisotropic rotating discs made of aluminum/aluminum-alloy matrix reinforced with silicon-carbide particulates where the creep is described by the threshold stress based creep law. Models are developed to ¯nd stress and strain rate distributions in a the composite disc. The constitutive equations are devel- oped using di®erent yield criteria and the impact of di®erent stress exponents on the stress/strain-rate distributions in the disc are investigated. To compute stress and strain rate distributions in the disc, the equilibrium equation of the continuum mechanics and the constitutive equations are solved. The value of stress exponent is chosen on the basis of results obtained. Also the analysis of the steady state creep in a rotating disc has been carried out in the presence of residual stress using Ho®man yield criterion. At the end the analysis has been carried out for creep in isotropic/anisotropic rotating disc made of FGMshaving linear and non-linear distributions of silicon carbide.