Modeling of Creep Behavior of a Rotating Disc in the Presence of Both Composition and Thermal Gradients

Abstract

The creep behavior of a rotating disc made of isotropic composite containing varying amounts of silicon carbide in the radial direction has been investigated in the presence of a thermal gradient, also in the radial direction. The variation of silicon carbide content has been so tailored as to contain larger amounts of particles in a highly stressed region. This type of inhomogeneous material is known as Functionally Graded Material (FGM). The thermal gradient experienced by the disc is the result of braking action as estimated by FEM analysis. The creep behavior of the disc under stresses developing due to rotation has been determined following Sherby’s law and compared with that of a similar disc following Norton’s law. The difference in the distribution of stresses and strain rates in the discs does not follow any definite trend but the values are somewhat different. The presence of thermal gradient and a linear particle gradient separately or their simultaneous presence result in a significant decrease in steady state creep rates as compared to that in a composite disc with the same average particle content (20 vol %) distributed uniformly and operating under isothermal condition. Further, the study revealed that the creep behavior of a FGM disc could be significantly improved by increasing the gradient of particle distribution while keeping the same average particle content of 20 vol % silicon carbide in the disc.