Biaxial Deformation Behaviors of C/C Composite at High Temperatures.

Abstract

Biaxial deformation behaviors of carbon fiber reinforced carbon (C/C) composite were investigated at three biaxial stress ratios T=0, 0.5 and 1 using a cruciform-type specimen with slots at high temperatures. The biaxial displacements were measured in center area of the specimen by means of a biaxial capacity-type extensometer. Finite element method was also performed to examine the validity of the geometry of the cruciform-type specimen with slots and to assess biaxial deformation behaviors of C/C composite at high temperatures. As a result, it was found that thermal stresses were restrained from genrating at high temperatures and uniform distributions of strains and stresses were realized in the center area of the specimen. The calculated biaxial strains were in quite good agreement with the measured ones by the biaxial extensometer. Accordingly, the analysis that used orthotropic theory was effective method to examine the biaxial deformation behaviors of C/C composite at high temperatures. Furthermore, it was indicated that C/C composite exhibited linear stress-strain response at high temperatures, independent of biaxial stress ratio.