Showing papers on "Functionally graded material published in 1970"

Constitutive Modeling Of Functionally GradedMaterial And Its Application To Fracture In FGM

Abstract: An analytical methodology is shown for studying a crack in a functionally graded material subjected to an intense thermal shock load. A theoretical elastoplastic material modeling of the functionally graded material is presented. Also independently a computational procedure of an elastoplastic constitutive law is introduced with the use of a micromecnanics analysis and a hierarchical neural network algorithm. The material is composed of ZrO and 77-6A/-4V, where the plastic flow is considered to occur in the titanium alloy phase. To detect the crack-tip fracture severity in the highly inhomogeneous media, r*integral parameter is employed for the thermal shock problem of the cracked material. Introduction In high temperature technology, multi-material bodies comprised of ceramics and high toughness materials such as metals have been thought. The discrepancies in the thermal expansion rates and other material properties between the materials causes a strength problems at the interface. Functionally graded material(FGM) is, hence, devised in the manner that the material composition is continuously varied with location in order to remove the strain discontinuity. By properly grading the composition of the constituents, the thermal stresses in the FGM may be minimized. FGM is, thus, inherently inhomogeneous, and in addition thermally inhomogeneous such that the material properties change over the wide range of temperature to that the material is designated to be subjected. The FGM is still on the materials research and development stage. To design the material, the prompt establishment of the analytical methodology is urged. For the analysis of such a material behavior and the structure, rapidly developing computational mechanics is best suited for its complexity. In the computational analysis of the FGM, the local macroscopic constitutive law for the averaged medium, where the matrix and/or the inclusion phases undergo thermo-elastoplasticity, must be known. When plastic flow occurs, if the volume fraction of the inclusion phase is high, interactions between inclusions may give a significant Transactions on Engineering Sciences vol 13, © 1996 WIT Press, www.witpress.com, ISSN 1743-3533