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J.N. Reddy Mechanical and Thermal Buckling of Functionally Graded Ceramic-Metal Plates R. A. Arciniega and J. N. Reddy Functionally graded materials (FGMs) are a special kind of composites in which the material properties vary smoothly and continuously from one surface to the other. These materials are microscopically inhomogeneous and are typically made from isotropic components. One of the main advantages of FGMs is that it mitigates severe stress concentrations and singularities at intersections between interfaces usually presented in composite laminates due to their abrupt transitions in material compositions and properties. Applications of FGMs are extensive especially in hightemperature environments such as nuclear reactors, chemical plants and high-speed spacecrafts. Usually, FGMs are made from a mixture of ceramic and metal or combinations of
different metals. It is known that these materials withstand high-temperature
gradient environments while maintaining their structural integrity. The ceramic
constituent of the material provides the high-temperature resistance due to its low
thermal conductivity. On the other hand, the ductility of the metal constituent
prevents fracture cause by stresses due to high-temperature gradient in a very short
period of time. Additionally, ceramic-metal FGMs with continuously varying volume
fraction can be easily manufactured. In this lecture, the mechanical and thermal buckling of functionally graded ceramicmetal
plates will be discussed. The formulation is based on a third-order shear
deformation theory of plates (see J. N. Reddy, Mechanics of Laminated Plates and
Shells. Theory and Analysis, 2nd ed., CRC Press, Boca Raton, FL, 2004). Results based
on the first-order theory are also included for comparison. A displacement finite
element model of the third-order theory is developed using C0 continuity.
Furthermore, a family of high-order Lagrange interpolation functions is used to avoid
shear locking. The stability equations are derived by using the Trefftz criterion.
Numerical results are compared and validated with those found in the literature.
Changes in the critical temperature due to the effects of temperature distributions,
volume fraction exponent, and geometric parameters will be examined. |
