Purpose -The purpose of this paper is to investigate creep in an internally pressurized thick-walled, closed ends cylinder made of functionally graded composite, having linear and non-linear distribution of reinforcement, using finite element (FE) analysis. Design/methodology/approach -FE-based Abaqus software is used to investigate creep behavior of a functionally graded cylinder. The cylinder is made of composite containing linear and non-linearly varying distributions of reinforcement along the radius. The creep behavior has been described by Norton's power law. The creep stresses and strains have been estimated in linear and non-linear functionally graded materials (FGM) cylinders and compared with those estimated for a similar composite cylinder but having uniform distribution of reinforcement. Findings -The radial stress in the composite cylinder is observed to decreases over the entire radius upon imposing linear or non-linear reinforcement gradients. However, the tangential stress in the cylinder increases near the inner radius but decreases toward the outer radius, on imposing linear or non-linear reinforcement gradients. The creep strains in the FGM cylinders are significantly lower than those observed in a uniform composite cylinder. Originality/value -The creep strains in an internally pressurized functionally graded thick composite cylinder could be reduced significantly by employing non-linear distribution of reinforcement along the radial direction.

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The steady state creep behaviour of a rotating FGM disc having linearly varying thickness has been investigated. The disc is assumed to be made of functionally graded composite containing non-linearly varying radial distribution of silicon carbide particles in a matrix of pure aluminum. The creep behaviour of the composite has been described by threshold stress based law. The effect of varying the disc thickness gradient has been analyzed on the stresses and strain rates in the FGM disc. It is observed that the radial and tangential stresses induced in the FGM disc decrease throughout with the increase in thickness gradient of the disc. The strain rates also decrease with the increase in thickness gradient of the FGM disc, with a relatively higher decrease near the inner radius. The increase in disc thickness gradient results in relatively uniform distribution of strain rates and hence reduces the chances of distortion in the disc.

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Purpose – The purpose of this paper is to investigate steady state creep behavior of a functionally graded rotating disc under varying thermal gradient (TG). Design/methodology/approach – The steady state creep in a rotating FGM disc with linearly varying thickness has been investigated by using von-Mises yield criterion. The disc under investigation is assumed to be made of FGM containing non-linear distribution of silicon carbide particle (SiCp) in a matrix of pure aluminum along the radial distance. The creep behavior of the FGM composite disc is described by threshold stress-based law. The stresses and strain rates in the FGM disc have been estimated for different kinds of TG. Findings – The results indicate that when the FGM disc is subjected to a radial TG, with temperature increasing with increasing radius, the radial stress in the disc increases over the entire disc but the tangential and effective stresses increase near the inner radius and decrease toward the outer radius. The imposition of such a radial TG in the FGM disc leads to significant reduction in the radial and tangential strain rates. With the increase in magnitude of TG in the FGM disc, the inhomogeneity in creep stresses increases but the inhomogeneity in strain rates decreases significantly, thereby reducing the chances of distortion in the FGM disc. Originality/value – The creep strain rates in rotating FGM disc could be significantly reduced when the disc is subjected to a radial TG, with temperature increasing with increasing radius.

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Mathematical model has been developed to investigate steady state creep in a variable thickness rotating disc made of functionally graded Al-SiCp. The SiCp content in the disc is assumed to decrease from the inner to outer radius. The creep behavior of the disc material is described by threshold stress based law with a stress exponent of 5. The stresses and strain rates in the disc are estimated by solving creep constitutive equations along with the equilibrium equation for a rotating disc. The stresses and strain rates have been estimated for similar FGM discs with three different thickness profiles i.e. constant thickness, linearly varying thickness and hyperbolic varying thickness. The FGM disc having hyperbolic thickness profile exhibits the lowest stresses and strain rates compared linear or constant thickness disc. The tangential and radial strain rates in FGM discs with linear and hyperbolic thickness profiles are respectively lower by about two and three orders of magnitude when compared to a constant thickness FGM disc. The FGM discs having linear and hyperbolic thickness profiles possess lesser chances of distortion due to relatively uniform distribution of radial strain rate.