Issue 64

Y. Zhang et alii, Frattura ed Integrità Strutturale, 64 (2023) 171-185; DOI: 10.3221/IGF-ESIS.64.11

2

a a a 1.99- (1- )[(2.15-3.93 +2.7 a

     

]

      a F = H I

H H

H H

(2)

3/2

a

a

  

  

  

1+2 1

H H

where:

: fracture toughness; : concentrated load in the span; : mass between the specimen supports (converted from the total mass of the specimen by the S/L ratio, L being the total length of the specimen); : gravitational acceleration; : the span between the two supports of the specimen; I K P mg g S

H: height of the specimen cross-section; B: thickness of the specimen cross-section; : effective crack length; a

/ MPa·m 1/2 − un ini IC IC K K

ini IC K

ini P

max P

c a

un IC K

ini un IC IC K /K

Sample

/kN

/kN

/mm

/MPa·m 1/2

ini max P /P

/MPa·m 1/2

S0-1 S0-3 S0-4 S1-1 S1-2 S1-3 S1-4 S2-1 S2-2 S2-4 S3-1 S3-2 S3-3 S3-4 S4-2 S4-3 S4-4

2.40 2.85 2.20 2.40 2.75 3.30 2.45 2.55 3.00 3.30 3.00 3.10 3.05 2.95 2.90 3.20 3.40

3.80 4.35 3.55 3.45 3.35 4.05 3.60 4.15 4.30 4.30 4.00 4.25 3.70 3.75 4.80 4.25 4.45

0.63 0.66 0.62 0.70 0.82 0.81 0.68 0.61 0.70 0.77 0.75 0.73 0.82 0.79 0.60 0.75 0.76

79 75 70 80 80 71 77 74 81 76 80 88 75 84 80 75 76

0.514 0.606 0.473 0.514 0.586 0.698 0.524 0.545 0.637 0.698 0.637 0.658 0.647 0.627 0.617 0.678 0.719

1.176 1.235 0.906 1.101 1.050 1.047 1.061 1.147 1.381 1.242 1.254 1.602 1.059 1.296 1.512 1.197 1.275

0.662 0.629 0.433 0.587 0.464 0.349 0.537 0.602 0.744 0.544 0.617 0.944 0.412 0.669 0.895 0.519 0.556

0.50 0.44 0.46 0.45 0.56 0.67 0.49 0.48 0.46 0.56 0.51 0.41 0.61 0.48 0.41 0.57 0.56

2.48 (0.27)

3.90 (0.33)

0.64 (0.02)

75 (3.68)

0.531 (0.056)

1.106 (0.143)

0.575 (0.101)

0.48 (0.02)

Average

2.73 (0.36)

3.61 (0.27)

0.75 (0.06)

77 (3.67)

0.581 (0.073)

1.065 (0.022)

0.484 (0.090)

0.54 (0.08)

Average

2.95 (0.31)

4.25 (0.07)

0.69 (0.07)

77 (2.94)

0.627 (0.063)

1.257 (0.096)

0.630 (0.084)

0.50 (0.04)

Average

3.03 (0.06)

3.93 (0.22)

0.77 (0.03)

81 (4.82)

0.642 (0.012)

1.303 (0.195)

0.661 (0.190)

0.50 (0.07)

Average

3.17 (0.21)

4.50 (0.23)

0.71 (0.07)

77 (2.16)

0.671 (0.042)

1.328 (0.134)

0.657 (0.169)

0.51 (0.07)

Average

Table 3: Double-K fracture parameters of specime ns (standard deviations in parentheses).

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