Papers by Author: Jian Ping Wang

Abstract: The functionally graded thermal barrier coating (TBC) serves in high temperature and/or high temperature gradient environment for a long time. According to the experimental and theoretical research, in the metal substrate and the metal-rich interlayer creep deformation will appear under high temperature environment. In order to design and optimize the compositional distribution of FGM, it is necessary to analyze the stress and strain responses taking into account the creep phenomenon of the materials. In this article, the thermo-mechanical responses of ceramic/metal functionally graded TBC in work environment are analyzed by a finite element method. The creep phenomenon of the metal and the interlayers are taken into account. The numerical results indicate that the creep behavior of all interlayers, even for the ceramic-rich interlayer, cannot be neglected in analysis. It is suggested that the creep phenomenon of the material is important in the functionally graded TBC systems.

Abstract: This paper studies the optimization problem of composition distribution of functionally graded material (FGM) coating subjected to steady heat flux loading. The investigation object of the paper is an infinite plate substrate with FGM coating in the surface. The materials are heated at the ceramic surface (upside) with a steady high-intensity heat flux input, and cooled at the metal surface (underside) with flowing liquid nitrogen. The thermal stress distribution and the temperature distribution are obtained by formulation. For optimization, the design variables are the thickness of each interlayer and the volume fraction distribution of the coating. The objective function is the danger coefficient and the restricted condition is the total thickness of FGM plate and heat insulation coefficient. In the paper, three different optimization schemes are considered and compared. The µGA and related parameters are discussed in detail. Optimizing the thermal stress distribution and minimizing the danger coefficient are carried out by µGA. The optimization results of composition distribution are gained, and the results show the optimum composition distribution can distinctly reduce the danger coefficient.