Study of mechanical properties and cracking extension resistance behavior of C/SiC composites by single edge notched beam and digital image correlation techniques

The carbon fiber reinforced silicon carbide matrix (C/SiC) composites were prepared by using precursor infiltration and pyrolysis method. Fracture characteristics of C/SiC materials were studied by single edge notched beam with the aid of digital image correlation (DIC) technique. It was found that DIC played an important role in in-situ monitoring full/local strain evolution and cracking growth during bending tests, which was useful for revealing potential failure micro-mechanisms of C/SiC composites. The results showed that the average fracture toughness K_IC and fracture strength of C/SiC were estimated as 7.81±0.12 MPa m^1/2 and 223.23±3.5 MPa, respectively. Moreover, the crack extension resistance curves (R-curve) in terms of stress intensity (K_R-curves) were determined on the basis of the crack initiation toughness K_IC. The values varied from 4.68 MPa m^1/2 to 16.83 MPa m^1/2 during the R-curve tests.