13th International Conference on Fracture June 16–21, 2013, Beijing, China the interface, as can be seen from the Fig.6, the normal crack hasn’t connected to the shear crack, the shear crack initials at a position near the interface end . For the damage and the debond of the interface, the CNT composite has been failed to take the load. The interface plays an important role to the mechanical property of the composites. The maximum stress appears in the corner of the interface, the stress concentration effect should be considered to predict the damage initiation and the crack propagation. 4. The discussion of mechanical property of CNT composites The crack progress and the fracture mechanism of the interface has been studied by the CZM model. The influence of the interface to the CNT composites can be reflected in the stress--strain curve of the whole unit cell, as is shown in Fig.7. Because of the effect of the interface, the relationship between stress and strain is nonlinear. At first, the composite displays linear characters, on account of the valid function of the interface before the stress gets to its strength value. The effective modules of the composites in the linear stage is 9.44GPa, CNT has the obvious reinforcing performance. Then accompanies with the crack propagation in the interface, the stress has an abrupt drop. The performance of the interface decides the mechanical property of the CNT composites. 0.000 0.002 0.004 0.006 0.008 0.010 0.012 0.014 0.016 0.018 20 40 60 80 100 120 stress(Mpa) strain effective stress Figure 7. Stress-strain curve of CNT composites 5. Conclusion 1. The CZM of the interface between the matrix and CNT has been established to predict the mechanical property of interface, and it is proved that CZM is effective in the nanocomposites. 2. The whole deformation and damage process of the interface has been studied through the FE simulation results. 3. The stress--strain curve of composites has been plotted to research the mechanical properties of the composites. It is with great importance to study the mechanical property of the interface to improve the performance of CNT composites. Acknowledge This work is supported by the National Natural Science Foundation of China under the Project Number 11172012, and the Ph. D programs foundation of the Ministry of Education under the Project Number 20101103110005, which are gratefully acknowledged. Reference
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