Issue 25

E. Maggiolini et alii, Frattura ed Integrità Strutturale, 25 (2013) 117-123; DOI: 10.3221/IGF-ESIS.25.17

Comsol has a built-in PDE Solver, including the Helmholtz equation solver. The linear elastic stress solution provides the local stress field. The Helmholtz equation (σ eff,IG ) can be directly solved on the same model. One of the obtained outputs is given in Fig. 2. By changing the angle of the notch and plotting the results, it is possible to compare the differences at the tip (Fig. 3). Except for smaller angles, σ eff,IG decreases by improving the opening angle of the notch. Alternatively, by considering the integral value, the Eq. (1) can also be evaluated by the Comsol solver; Fig. 3 also shows such type of result (σ eff,int ).

Figure 2: Example of plot of the σ eff,IG

10

8

6

σ eff,IG σ eff,int

4 σ /σ nom

2

0

0

30

60

90 120 150 180

2 α [°]

Figure 3: Trend of σ eff,IG

VS σ eff,int

σ eff,IG [MPa]

σ eff,int [MPa]

2α [°]

Difference

[%]

0

9.47 9.37 9.74 9.37 7.67 6.26 4.61 1.00

7.47 7.58 7.97 7.82 6.64 5.56 4.23 1.00

-21.1% -19.1% -18.2% -16.5% -13.4% -11.1%

30 60 90

120 135 150 180

-8.2% 0.0%

Table 1 : Value of σ eff,IG

and σ eff,int

at any tested angle.

119