Issue 51

B. Zaoui et alii, Frattura ed Integrità Strutturale, 51 (2020) 174-188; DOI: 10.3221/IGF-ESIS.51.14 184 towards the fiber is characteristic of this propagation kinetics variation of the crack. When the crack crosses the entire fiber and tends towards the second interface, this speed is again slowed down by the strong crack-interface interaction. This behavior is all the more marked as the commissioning stress is more intense. 0,000 0,005 0,010 0,015 0,020 0,025 0 10 20 30 40 50 60 70 80 K I ( MPa.mm 1/2 ) a (mm)  = 50 MPa  = 80 MPa  = 120 MPa Matrix Fiber Figure 8: Effect of the commissioning stress intensities on matrix crack propagation in mode I. 0,000 0,005 0,010 0,015 -200 -150 -100 -50 0 50 100 150 K I ( MPa.mm 12 ) a (mm)  T = 400°C,  = 120 MPa  T = 600°C,  = 80 MPa  T = 800°C,  = 50 MPa Matrix Fiber a) 0,000 0,005 0,010 0,015 0 2 4 6 8 10  T=400°C,  =120MPa  T=600°C,  =80MPa  T=800°C,  =50MPa K II ( MPa.mm 1/2 ) a (mm) Matrix Fiber b) 0,000 0,005 0,010 0,015 -3,0 -2,5 -2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0  T = 400°C,  = 120 MPa  T = 600°C,  = 80 MPa  T = 800°C,  = 50 MPa Fiber Matrix K III ( MPa.mm 12 ) a (mm) c) Figure 9: Variation of the stress intensity factor according to applied thermomechanical stresses intensities. a) in mode I, b) in mode II, c) in mode III.