Modeling Of Hysteresis Loops And Life Prediction In Cross-ply Ceramic Matrix Composites

Cross-ply ceramic matrix composite has the characteristics of high-temperature resistance, good friction properties, high specific strength and other advantages, and overcome the shortcoming of the unidirectional ceramic composites which is low strength in off-axis direction. The researches on the damage mechanism of cross-ply ceramic composites are the premise for its application to structural components, so it is important to model the hysteresis loops and predict life in cross-ply ceramic matrix composites.Stress-strain curve of cross-ply ceramic matrix composites under quasi-static un-axial loading were modeled. The predominant modes of damage of the cross-ply laminates are transverse cracking of the 900 plies, matrix cracking of the 00 plies, interface de-bonding and fiber failure. This thesis analyzed the stress distribution of cross-ply ceramic matrix composites under damage by laminate shear-lag theory, discussed the factors which influenced the stress distribution. The tensile stress-strain curve was modeled by combining laminated shear-lag theory and failure criteria, and the influence of the factors on the stress-strain curve was discussed. The stress-strain curve predicted was compared with the experimental data from the references and the experiments of C/SiC cross-ply laminates. The results from the present analysis agreed well with the experimental data.The cross-ply hysteresis loops were modeled by combining laminated shear-lag theory and hysteresis theory, and the influence factors on hysteresis loop were discussed. The fiber failure statistics model combined with Evans interface wear model was used to predict the S-N curve of ceramic matrix composites. The stress-strain curve under cyclic loading and the S-N curve predicted in this paper were compared with the experimental data from references and the tests of C/SiC cross-ply laminates. The predicted results agreed well with the experimental data.