Analysis Of Dynamic Characteristics For Random Functionally Graded Material Structures

Functionally Graded Materials, as called FGM bellow, are new kinds of non-uniform composite materials that material properties and function with gradient distribution for elements of materials distribute with gradient mode. With component volume content changes continually in space, FGM's structure properties change in the same way. That's the reason FGM eliminate mutants of material properties, avoid or reduce effects of stress concentration better. FGM can mix thermo stability and resistant to corrosion from ceramics, and high strength and high toughness from metal. FGM also have a good ability to reduce unordinary of bond strength and low thermal expansion for the barely match of ceramics and metal. FGM have good ability in high-temperature environment, are considered as kinds of potential materials that can be used in High-speed spacecraft, nuclear industry and the chemical industry in the future. Therefore,The study of mechanical behavior of FGM structure has attracted the interest of many researchers.The random factor method is developed for the stochastic dynamic characteristics analysis of beams that are made of functionally graded materials(FGM) with random constituent material properties in this paper. The effective material properties of FGM beams are assumed to vary continuously through different directions according to the power law distribution. In the proposed method, the randomness of the dynamic characteristics is explicitly expressed by random factors of constituent material parameters, and the statistics(means and variances) of modal parameters can be analytically computed by the statistics of random inputs with little computational efforts. Compared with the first-order perturbation technique and the Monte-Carlo simulation method, the proposed method is illustrated and verified by a FGM cantilever beam with material variation through the thickness or axial direction, and the contributions of random material properties to the dispersion of dynamic characteristics for the structure are systematically investigated. The numerical results also show the dominant effect of constituent volume fraction index on the dispersion of dynamic characteristics.