Fatigue Crack Paths 2003

Unfortunately, the available data did

Steel - Cast Iron

not allow us to propose any efficient

0.010.010.10 10

100 1000 10000 100000 1000000

rule capable of estimating the

a0=(213.5/ΔσΔσΔσΔσ0) (a) a0=(394.2/ΔσΔσΔσΔσ0)3.03 a0=(115.6/ΔσΔσΔσΔσ0)3.0 3.03

CI,R=-1

threshold value of the stress intensity

CI, R>0

S,R=-1

factor, even if a synthesis diagram has

S, R=0

been proposed.

S, R=0.1

S, R>0.1

Finally, it is important to highlight

that, even though the proposed data

re-analyses can represent an useful

tool to perform a preliminary fatigue

assessment, it is Author’s opinion that

these values are only engineering

ΔσΔσΔσΔσ0/a0

[MPa/mm]

estimations. In fact, materials can

Aluminium

show behaviours that could be

affected by different parameters (like

10

3.45

=(163.6/ΔσΔσΔσΔσ

a 0

0 )

heat

treatments,

manufactory

R=-1

processes, etc.), which have not been

R=0-0.1

1

systematically taken into account in

the present study.

0.1

3.45

a 0 =(93.4/ΔσΔσΔσΔσ

0 )

0.00.01

3.45

a 0 =(53.3/ΔσΔσΔσΔσ

0 )

R E F E R E N C E S

(b)

10

100

1000

10000 100000

1. El Haddad, M. H., Dowling, N.

ΔσΔσΔσΔσ0/a0

[MPa/mm]

F., Topper T. H., Smith, K. N.

(1980) Int. J. Fract. 16, 15–24.

Steel - Cast Iron - Aluminium

2. Atzori, B., Lazzarin, P. (2000)

0.00.010.010.10

Int. J. Fracture 107, L3-L8.

a0=(2.18·10-3·E/ΔσΔσΔσΔσ0)3.57

CastIron

B., Lazzarin,

3. Atzori,

P.,

Steel

Meneghetti, G. (2003) Fatigue

Aluminium

Fract. Engng. Mater. Struct. 26,

257-267.

a0=(0.6·10-3·E/ΔσΔσΔσΔσ0)3.57

4. Taylor, D. (1999) Int. J. Fatigue

21, 413-420.

(c)

a0=(1.14·10-3·E/ΔσΔσΔσΔσ0)3.57

5. Taylor, D., Wang, G. (2000)

Fatigue Fract. Engng. Mater.

1E-05 0.0001 0.001 0.01 0.1

1

10

ΔσΔσΔσΔσ0/(E·a0)

[1/mm]

Struct. 23, 387-394.

6. Susmel, L., Taylor, D. (2002) In:

FATIGUE2002, Blom, A. (Ed.),

Figure 5. Relatiohship between a0 and Δσ0/a0

1889-1897.

for steel and cast-iron (a) and for aluminium

Susmel, L., Lazzarin, P. (2002)

7.

alloy (b). Universal a0 vs. Δσ0/(Ea0) diagram

Fatigue Fract. Engng. Mater.

(c).

Struct. 25, 63-78.