Design and Modeling Methods for Components Made of Multi-Heterogeneous Materials in High-Tech Applications

Abstract

With rapid developments of high-tech in various fields, there appear more critical requirements for special functions of components/products. For example, the thermal deformation of satellite’s paraboloid antenna (10 meters in diameter) should be controlled within 0.2 mm in order to work well under the environment with large variations in temperature (−180°C∼120°C). To fulfil it, its thermal expansion coefficient should be close to zero. Another example is that Poisson’s ratios of sensors should be negative in order to increase their sensitivities to hydrostatic pressures. If Poisson’s ratio of a sensor can be changed from an ordinary value of 0.3 to −1, its sensitivity will be increased by almost one order of magnitude. The third example is about the cylinders of vehicular engines or pressure vessels. They are subjected to a high temperature/pressure on the inside while the outer surface is subjected to ambient conditions. It is desirable to have ceramic on the inner surface due to its good high temperature properties while it is also desirable to have metal away from the inner surface owing to its good mechanical properties. Joining the two materials abruptly will lead to stress concentration at the interface. A gradual change of constituent composition is thus required. But, the components made of homogeneous materials rarely possess all these special functions mentioned above. Recently attention has focused on heterogeneous materials, including composite materials, functionally graded materials, and heterogeneous materials with a periodic microstructure.