Interlaminar shear damage mechanisms of a 2D-C/SiC composite at elevated temperature in vacuum

• Interlaminar shear failure is dominated by the intra-bundle cracks and fiber/matrix interface.
• Main cracks were initiated with in 90° fiber bundles and originated from intra-bundle pores.
• The crack always propagated along fiber/matrix interface and oriented 45° to loading direction.

The aim of the study is to reveal the damage mechanisms of a plain woven carbon fiber cloth reinforced silicon carbide composite (2D-C/SiC) under interlaminar shear stress at elevated temperature. The interlaminar shear tests were carried out by compression of a double-notched specimen. Damage mechanisms were revealed by loading/unloading experiments. The damage evolution mainly involves the initiation and propagation of intra-bundle cracks, matrix cracking and emergence of the cracks. Release of the residual thermal stresses in the matrix and improved bonding of fiber/matrix interface enhance the resistance to initiate cracks. More cracks could be generated above the preparation temperature, and result in the degradation in interlaminar shear strength and crack initiation stress.