Interlayer Crack Extension Mode in Laminated Carbon/Carbon Composites

As a high performance thermal-resistant composites, carbon/carbon composites have the highest mechanical strength in the temperature more than 1600 , but the brittleness of C/C is the main shortcoming limitting its usage. Delamination constitutes the principal threat to structure strength of two dimensional carbon/carbon composites. There are three kinds of crack extension modes in general. In this paper, two kinds of modes, that is, mode I and n were discussed. On the basis of failure evolution features in composites, the delamination crack extension energy G ＩC、 G Ⅱ C, the extension patterns and the influencing factors were researched. It is revealed that the critical interlaminar crack extension energy of 2D carbon/carbon increases as the material density goes up, therefore, the ability to resist fracture evolution improves. The experimental results show that the extension energy G Ⅱ C rises with the increase of fiber volume fractions. Also, it is observed that the G Ⅱ C increases greatly after filling the matrix with powdered pyrolytic carbon and graphite.