| According to the failure characteristics of ceramic matrix composites, this thesis established the multi-scale static strength failure analysis method for the ceramic composite structures.Based on the progressive failure analysis method, this thesis developed the unified macro- and micro- mechanical progressive failure model for the ceramic composite structures by using the micro-mechanical failure model and stiffness degradation model. The numerical simulation of unidirectional and cross-ply ceramic composite plates with a central hole under tensile loading was derived. The damage evolution and the ultimate failure loads of the composite plates were predicted. The results agreed with the experiment observations, which prove the efficient of the present model.A multi-scale stochastic progressive failure analysis model for composite structure was developed based on unified macro- and micro- mechanical progressive failure model and considering the effect of the composite strength randomicity. The failure process of smooth tensile specimens of unidirectional and cross-ply ceramic composites was analyzed. The results agreed with the experiment observations. It shows that the multi-scale stochastic progressive failure analysis model overcomes the weakness of the traditional model which requires the obvious danger points in the structure and can be applied in a wider range.Taking one type of aircraft engine's turbine rotor blade as prototype, the failure process of two kinds of laminated ceramic composite blades was analyzed by the multi-scale stochastic progressive failure analysis model. The results preliminary demonstrated the possibility of this model for analyzing the engineering problems. As the ceramic composites possess high specific strength and specific stiffness, they can be utilized to manufacture lighter structures meeting the requirements of strength and stiffness. Besides, this thesis made some suggestions on the design of ceramic composite components.
|
PDF Full Text Request