PSI - Issue 28

Bruno Atzori et al. / Procedia Structural Integrity 28 (2020) 1329–1339 Bruno Atzori et al./ Structural Integrity Procedia 00 (2019) 000–000

1337

9

100

1000

 =810  N -0.058

10  K(N) [MPa m 1-  1 ]

 K=274  N -0.188

 n =1728  N

-0.188

100

 n [MPa]

V=45° V=90° Plain material r n =0.1 mm, 2  =45° r n = .1 mm, 2  =90° Plain material

1

10

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

N f , number of cycles to failure

Fig.5 Fatigue curves of plain and cracked AISI 304L stainless steel (2 nd batch).

K t,point

1 st batch from Meneghetti et al (2013)

Fig. 6. Linear elastic stress fields evaluated by finite element analyses for the different analysed specimen geometries.

Therefore the  0n values were calculated, according to Eq.(20): Δσ ୬ ሺ ଴ ሻ ൌ Δσ బ ୏ ౪ǡ౦౥౟౤౪ ሺ୶ሺ୒ బሻ ሻ

(20)

and the results are summarised in Table 3. It is worth noting that for x= x(N 0 ), the influence of plasticity was not taken into account because the stress was picked up at x(N 0 ) where the stress field is close to that of a the equivalent crack, while for x= x(N th ), the K p coefficient was used: