Issue 33

R.C.O. Góes et alii, Frattura ed Integrità Strutturale, 33 (2015) 89-96; DOI: 10.3221/IGF-ESIS.33.12

modulus, a typical value for steels. The models were built with symmetry with respect to the xy plane at the plate mid thickness and to the xz plane. The EH models received additional symmetry with respect to the yz plane. The uniform load is applied in the model as a uniform tensile stress on the upper plate face y  H . The notch tip region is described by structured meshes with a maximum element size of 0.1  at the notch tip, where   b 2 /a is the notch tip radius. The dimensions of the analyzed notches are listed in Tab. 1.

notch b/a

 /a

B/ 

1

1

0.1, 0.2, 0.4, 0.6, 1, 1.5, 2, 3, 4, 6, 8, 10, 20

0.5 0.25

0.4, 0.8, 2, 2.8, 4, 6, 8, 12, 16, 32, 48

elliptical

0.2 0.04

3, 6, 10, 15, 20, 30, 50, 75, 100

0.1 0.01

0.4, 0.6, 1, 2, 4, 6, 10, 20, 40, 60, 100

1

1

0.2, 0.3, 0.5, 0.7, 1, 2, 3, 5, 7, 10, 20, 30

0.5 0.25

0.16, 0.24, 0.4, 0.8, 2, 4, 8, 12, 16

semi- elliptical

0.2 0.04

0.5, 1, 3, 10, 20, 30

0.1 0.01

0.6, 6, 10, 20, 40, 60, 100, 200, 400

Table 1 : Elliptical and semi-elliptical notch parameters analyzed in the present FE models.

Figure 2 : K  /K t

Figure 1 : K  /K t

distribution along the notch tip front, for a large

distribution along the notch tip front, for a large

plate with an elliptical hole with b/a = 0.5 and  /a = 0.25 .

plate with an elliptical hole with b/a = 0.5 and  /a = 0.25 .

Fig. 1-2 shows typical K  / K t distributions along the notch tips of EH with b/a  0.5 and  /a  0.25 . Note that K   K  , and that their maximum values occur close to the surface of thick plates (with B >>  ), whereas for thinner plates they occur at the plate center. K  / K t ratios depend on B/  , see Fig. 3. For relatively blunt notches (those with low B/  ratios), the maximum values of the stresses and strains along the notch tip  max and ε max occur on the middle plane of the plate, but for sharper notches these values dislocate towards the plate free surfaces (located at z/B  0.5 ), in a slightly decoupled way. K  and K  can differ up to 15% in such plates. The maximum SCF at the notch tip K  max can be up to about 8% higher than the 2D SCF K t , a non-negligible difference. Therefore, even experimental K t values, measured as usual at the notched component free surfaces, may underestimate the actual value of  max at such notch tips, so 3D effects on stress/strain fields along notch tips may indeed be relevant for some practical applications. and K  / K t

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