i-doser version 4.5 (cracked) over 200 doses

For the same process zone size, critical strain energy release rate G c ≈ 7 kJ/m 2 was estimated for weak interface composite against ≈30 kJ/m 2 for strengthened interface composite.

Both approaches provided comparable data dependent on process zone size. 2 In, 43 fracture toughness of 2D woven SiC/SiC composites was evaluated using strain-energy-release rate – process-zone size relation and J-integral approach. The above mentioned stress intensity factors are maintained up to at least 1400☌. 2,40 However, it is worth pointing out that this estimate has no absolute value, even if it reflects high damage tolerance for SiC/SiC composites. K IC ≈ 30 MPa m was measured on SENB test specimens. Although the invalidity of the stress intensity factor concept is not questionable, K IC is sometimes used when comparing CVI SiC/SiC composites to other materials. 43 Due to the presence of a large process zone, and the resulting absence of a well-defined straight crack, the conventional concepts of fracture mechanics are not appropriate (critical stress intensity factor K IC ) or cannot be easily determined ( strain energy release rate, J integral). Extension of the notch or the crack results from the random failures of fiber bundles located within the process zone.

Matrix cracking is an alternative mechanism of energy dissipation.Ī process zone of diffused matrix micro cracks is generated at the tip of a notch or of a pre-existing main macroscopic crack. The density of matrix cracks is enhanced by strengthened interfaces: the crack spacing distance may be as small as 10–20 µm whereas the crack spacing distance is at least 10 times larger in the presence of rather weak interfaces. The CVI SiC/SiC composites develop a network of matrix cracks under load. Jacques Lamon, in Comprehensive Nuclear Materials (Second Edition), 2020 7.13.6.6 Fracture Toughness

I-doser version 4.5 (cracked) over 200 doses