Creep behavior of a rotating functionally graded composite disc operating under thermal gradient
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3/6/04
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Creep Behavior of a Rotating Functionally Graded Composite Disc Operating under Thermal Gradient V.K. GUPTA, S.B. SINGH, H.N. CHANDRAWAT, and S. RAY Creep behavior of a rotating disc made of isotropic functionally graded material (FGM) has been investigated. The disc under investigation is made of a composite containing silicon carbide particles in a matrix of pure aluminum. The creep behavior has been described by Sherby’s law. The disc is considered as having a thermal gradient in the radial direction. The present analysis indicates that for the assumed linear particle distribution, the steady-state strain rates are significantly lower compared to that in an isotropic disc with uniform particle distribution. It is also found that the strain rates in composite discs operating under thermal gradient are reduced as compared to similar discs under a uniform average temperature.
I. INTRODUCTION
RAPID growth in technology has ushered in an era when it is possible to synthesize materials for components that exhibit a variation/graded-variation in their properties. Typically, under severe environments such as high temperature or thermal gradients, the conventional materials (metals or ceramics) alone may not survive. Thus, a new material concept of functionally graded materials (FGMs) emerged and led to the development of superior heat-resistant materials. Such materials withstand severe thermomechanical loadings. These are composites and are provided with heat-resistant ceramics on the high-temperature side and tough metals with high thermal conductivity on the lower temperature side.[1–4] In FGMs, the constituents (or their contents) vary in some direction, enabling these materials to provide unique performance. Ceramic-particle/whisker-reinforced metal matrix composites have shown superior high-temperature properties and are finding increasing application in the manufacture of components exposed to high temperatures.[5] Nieh[6] has shown that an aluminum-based composite containing silicon carbide whisker has better creep resistance compared to the base aluminum alloy. Pandey et al.[7] studied the steady-state creep behavior of Al-SiCp composites under uniaxial loading condition in the temperature range between 623 and 723 K for different combinations of particle size and volume fraction of reinforcement. They found that the composite with finer particle size has better creep resistance than that containing coarser ones. Zhu and Miller[8] examined the creep behavior of FGM, having a thermal barrier coating of zirconium-8 wt pct yttria on a bond coat of Fe-25Cr-5Al-0.5Y plasma sprayed on 4140 steel. The thermal gradient was produced by laser heating on the ceramic surface. They noticed primary creep in the ceramic layer. However, time-dependent, temperature-dependent, and V.K. GUPTA, Assistant Professor, and H.N. CHANDRAWAT, Professor, Department of Mechanical Engineering, and S.B. SINGH, Senior Lecturer, School of Mathematics and Computer Applications, are with the Thapar Institute of Engi
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