Optimization Research And Fracture Properties Of SiC/Al Functionally Gradient Material Under Elevated-Temperature

Modern aviation industry has put forward severe requirements for super high temperature materials: the materials must on one hand survive the forceful thermal shock, thus they should hold excellent properties in both high temperature resistance and heat insulation; on the other hand they have to possess better heat conductibility and better performance under low temperature so as to provide themselves with sufficient cooling effect; meanwhile, they are required strong and ductile enough to bear the mechanical loading and endure thermal stress results from thermal gradient. The Functionally Gradient Materials(FGM) hatched from such practical requirements are capable of meeting such severe demands.This study centers on the mechanical behaviors of SiC/Al FGM specimen which exactly including two kinds of samples: compact tension specimen and a compound sample. The compact tension specimens are designed to subject to loads of mechanical, thermal and combined loading. We thus observe and demonstrate the crack propagation behavior in samples, and of course we have finished some calculation in advance that can forecast the crack behaviors in the test, but that is not simply enough, at the same time we record experimental images and according to which we could work out strain distribution in the region that attracts our attention. After this primary work, we have to conduct the other approach to the research-by means of advanced computer technique which makes our research vision possible. Exactly we figure out the crack toughness of these specimens under different loading conditions and the strain distribution in them. This is the basic idea of what we do and by the same guideline we research the compound sample, and at last we propose an optimization to enhance material properties and discuss the factors which impact influence on the optimization.On the basis of SiC/Al FGM that used in the ground-to-air missile gas helm, this paper carrys out novel research work in the following aspects:success of high temperature Moire grating technics and application of MoiréInterferometry to the test work of ceramet composite; a successful forecast of crack propagation behavior in the specimen is obtained by introducing Ansys and further two crack propagation parameters are advanced; optimization result is obtained from optimization analysis in two dimensions of SiC/Al FGM used in gas helm.