Long-Term Four-Point Bending Test

Figure 4 shows both the single and average crack mouth opening displacement vs time relationships, CMOD—t, for the two pre-crack widths investigated

Table 2 Fibre distribution parameters obtained after the monotonic four-point bending tests

Series

N (fibres/cm2)

Nf (fibres/cm2)

Пв (-)

f«* (-)

Avg.

CoV (%)

Avg.

CoV (%)

Avg.

CoV (%)

Avg.

CoV (%)

в = [0-15°]

2.12

21.1

1.18

27.5

0.875

1.0

0.52

2.5

в = [15-45°]

1.76

11.8

0.67

28.6

0.807

4.4

0.52

2.6

в = [45-75°]

1.53

25.9

0.46

19.6

0.730

6.4

0.58

8.8

в = [75-90°]

0.87

21.8

0.15

78.4

0.672

12.9

0.62

15.2

Crack mouth opening displacement, CMOD, versus time relationships

Fig. 4 Crack mouth opening displacement, CMOD, versus time relationships

(i.e. wcr = 0.3 and 0.5 mm) obtained during the long-term four-point bending tests. During the test execution, none of the specimens entered into the tertiary creep stage, in which occurs failure due to creep. In general, the evolution of the wcr = 0.3 and 0.5 mm responses with time was similar, and the higher CMOD levels registered for the wcr = 0.5 mm series was a direct consequence of the higher damage at the fibre/matrix interface imposed by the higher pre-crack width. Note that the high scatter in the specimens’ responses is ascribed to distinct applied load levels, notch orientations and locations.

 
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