Issue 51

B. Zaoui et alii, Frattura ed Integrità Strutturale, 51 (2020) 174-188; DOI: 10.3221/IGF-ESIS.51.14

60

K K K

( Mode I ) ( Mode II ) ( Mode III )

50

I

II

40

III

0 K (MPa.mm 1/2 ) 10 20 30

-10

0,0 2,5 5,0 7,5 10,0 12,5 15,0 17,5 20,0 22,5 25,0 -20

   (10 - 6 K -1 )

Figure 4: Variation of the stress intensity factor in modes I, II and III as a function of the gap of the thermal expansion coefficients of the matrix and the fiber: a = 13mm, ΔT = 800 ° C.

10 11 12 13 14

100 150 200

b)

a)

Matrix

Matrix

Fiber

Fiber

K II ( MPa.mm 1/2 )

-450 -400 -350 -300 -250 -200 -150 -100 -50 0 50

0 1 2 3 4 5 6 7 8 9

I ( MPa.mm 1/2 )

 T = 400°C  T = 600°C  T = 800°C

 T = 400°C  T = 600°C  T = 800°C

K

0,000 0,005 0,010 0,015 0,020 0,025 -1

0,000

0,005

0,010

0,015

0,020

0,025

a (mm)

a (mm)

C)

0,0 2,5

-7,5 -5,0 -2,5

Matrix

Fiber

-25,0 -22,5 -20,0 -17,5 -15,0 -12,5 -10,0 K III (MPa.mm 1/2 )

 T = 400°C  T = 600°C  T = 800°C

0,000 0,005 0,010 0,015 0,020 0,025

a (mm)

Figure 5: Effect of elaboration temperature of the composite on the matrix crack propagation. a) in mode I, b) in mode II, c) in mode III.

181