Compressive testing and failure analysis of three-dimensionally reinforced carbon/carbon composites

It is important to reveal the performance of carbon/carbon composites subjected to complex loading,which can provide a basis for developing the failure laws of carbon/carbon composites.The uniaxial and biaxial compressive performances of three-dimensional reinforced carbon/carbon composites (3D C/C) were investigated in this paper.The results showed that the compressive strength becomes larger when the loading direction parallels to the z-direction of 3D C/C.The uniaxial compression failure was mainly caused by fracture fiber bundles to form an overall shear fault in the z-direction.The failure mode was delamination of fiber bundle/matrix interface for the x- and y-direction samples.The biaxial compressive failure of x-y direction compressioncompression specimen was caused by the low interlaminar shear strength.In addition,for y-z and z-x direction compression-compression samples,the shear-type failure wasformed on the surface of the specimen plumbing the loading direction.Overall,the weak-interface is still a main factor to influent the fracture mechanism of 3D C/C.