Issue 43

F. Berto et alii, Frattura ed Integrità Strutturale, 43 (2018) 1-32; DOI: 10.3221/IGF-ESIS.43.01

W

0.4  m  R 0  500  m 2.5   t  1200 MPa 0.15   IC  55 MPa m 0.5 0.1   0.4

0   /R 0  1000 0  2   150° Mode 1 and mixed mode (1+2)

About 1000 data from static tests

W

c

1.6

Acrylic resin

1.2

0.8

R 0 r 0

Duralluminium PVC

R 0

Steel AISI O1

ceramic materials PMMA data metallic materials and other materials

0.4

r 0

R

R 0

+r 0

0

R  0

1

10

1000

100

0.1

 /R 0

Figure 3: Synthesis of data taken from the literature. Different materials are summarized, among the others AISI O1 and duralluminium.

10

R 0 =0.28 mm 900 fatigue test data Various steels

0.01 Averaged strain energy density  W [Nmm/mm 3 ] 0.1 1.0

2 

R 0

R 0

Inverse slope k=1.5

T  W

= 3.3

0.192

0.105

2D, failure from the weld toe,  R = 0 2D, failure from the weld root,  R = 0 Butt welded joints -1 <  R < 0.2 3D, -1 <  R < 0.67 Hollow section joints, R = 0

P.S. 97.7 %

0.058

10 4

Cycles to failure, N

10 5

10 7

10 6

Figure 4: Fatigue strength of welded joints as a function of the averaged local strain energy density; R is the nominal load ratio.

value as soon as  1 N A K

where both λ 1

and e 1 depend on the V-notch angle. Eq. (5) makes it possible to estimate the R 0

= 5  10 6 cycles and in the presence of a nominal load ratio equal to zero a mean value  1 N A K

are known. At N A

and Δ σ A

5