Modeling Of Manufacturing Processes Of Carbon Matrices Composites And The Description Of Mechanical Properties Of The Material During The Process

Carbon-carbon composites are widely applied in the area of astronautics and aeronautics. As a kind of advanced composites, its properties are known to depend essentially on the technological regimes of its manufacturing processes. This present dissertation is devoted to the modeling of manufacturing processes of the composites and focuses on establishing the processing-microstructure-property relation to enable design of internal architecture to predict and optimize properties.Based on rational assumption, the C/C composite material is considered as a six-phase system (including carbon fiber phase, liquid pitch phase, solid pitch phase, solid residue phase of pyrolysis of the pitch matrix, gas phase and graphitized carbon phase of matrices) during all manufacturing processes. In view of the mechanism of chemical reactions and the Arrhenius law, phase transformations in a C/C composite under manufacturing processes are described by a group of non-linear differential equations of heat mass transfer and the temperature field within the composite material is characterized by the developed heat conduction equation. This dissertation provides the changes of volume concentrations of six components of the materials that occur during the technological cycles of manufacturing. With the comparison of our results and experiment data, it is showed that this paper's modeling of manufacturing processes of C/C composites is reasonable and effective, and the precision is satisfied.With the concept of the asymptotic averaging theory, this paper shows the cubic model considering the periodic cell of matrix as hollow cubes with a cube of fluids inside and hollow cubes of other solid phases outside. Then we provides formulae of effective elastic properties and strength of the matrix with multi-phases. After comparing results from the cubic model with those via FEPG software based on multi-scale method, it is found that the present model of matrix is reasonable and effective. With the help of the numerical simulation of manufacturing processes of C/C composites, we makes the prediction of changes in mechanical properties of the matrix (such as elastic moduli, strength,...