Optimization Of Metal/Ceramic FGM Coating By Genetic Algorithms

Ceramic/metal Functionally Graded Materials (FGMs) is one of most flourishing research fields at present all over the world. The important idea of FGMs is that material can be designed, i.e. according to the request of engineering application, the optimum solution scheme is obtained by rational selection of material system, method of fabrication, componential distribution, micro-structure and geometry size etc. The idea that material can be designed has overstepped traditional FGMs fields and is widely applied on other high technology fields.With the support from the National Natural Science Foundation of China, this paper studies the optimization problem of thermal stress of ceramic/metal FGM coating by micro-Genetic Algorithms. The study object is two typical FGM coating structure-a hollow cylinder and an infinite plate. Then, the paper fundamentally discusses the optimization problem of fracture performance of ceramic/metal FGM coating by the case of interface edge-cracks.Firstly, this paper describes the optimization problem of thermal stress of fabrication process and steady work process for the hollow cylinder and the infinite plate. Then, thermal stress distribution is calculated making use of theoretical formulation and the results can be validated by finite element method. In optimization, the restriction condition is heat insulation performance and the objective function is danger coefficient. The difference from the traditional optimization method of FGMs is that this paper abandons the hypothesis of componential distribution on the basis of power exponent and directly considers the componential ratio and the thickness of each interlayer as design variable of optimization. The method can seek the optimum solution in more capacious space. The optimization results of the two typical structure show that the optimization scheme of this paper is more rational and effective than traditional optimization method.For the optimization problem of FGMs fracture performance, this paper fundamentally studies the FGM coating plate with interface edge-cracks, and establishes the approximate analysis method of the driving force for interface edge-cracks growth-energy release rate. This paper considers energy release rate as objective function and the optimization problem of FGMs fracture performance is carried out by the paper mention optimization scheme.The emphasis of this paper is the optimization scheme of ceramic/metal FGM coating. Through this paper study, the more rational and effective optimization scheme of ceramic/metal FGM coating is established than traditional optimization method. Furthermore, some results with direct significance are obtained for engineering application of FGM coating.