Issue 38

A. Niesłony, Frattura ed Integrità Strutturale, 38 (2016) 177-183; DOI: 10.3221/IGF-ESIS.38.24

a)

b)

x 10 −3

10 3

7

( σ a

)

p σ

T 1

a

= 1 . 0

( τ a

)

6

p τ

T 2

a

4 ( τ a ), MPa − 1 5 a

σ a , τ a , MPa

3

( σ a ), p τ

2

a

p σ

= √ 3 · 200; m = 8; N 0 = 200; m = 8; N 0

1

= 2 · 10 6

Tension: S f Torsion: T f

= 2 · 10 6

10 2

0 100 200 300 400 500 600 700 800 0

10 2

10 4

10 6

10 8

, τ a

, MPa

N , cycles

σ a

c)

d)

10 3

10 3

T 1

T 1

= 3 . 16

= 0 . 133

T 2

T 2

σ a , τ a , MPa

σ a , τ a , MPa

= √ 3 · 200; m = 8; N 0 = 200; m = 12; N 0

= 2 · 10 6 = 2 · 10 6

= 2 · 10 6

Tension: S f Torsion: T f

= 300; m = 8; N 0 = 200; m = 8; N 0

Tension: S f Torsion: T f

= 2 · 10 6

10 2

10 2

10 2

10 4

10 6

10 8

10 2

10 4

10 6

10 8

N , cycles

N , cycles

e)

f)

10 3

10 3

T 1

T 1

= 0 . 421

= 0 . 0422

T 2

T 2

σ a , τ a , MPa

σ a , τ a , MPa

= 2 · 10 6

= 2 · 10 6

Tension: S f Torsion: T f

= 300; m = 8; N 0 = 200; m = 12; N 0

Tension: S f Torsion: T f

= 400; m = 8; N 0 = 200; m = 12; N 0

= 2 · 10 6

= 2 · 10 6

10 2

10 2

10 2

10 4

10 6

10 8

10 2

10 4

10 6

10 8

N , cycles

N , cycles

Figure 1: PDF of amplitudes used for computation of fatigue life T1 and T2 (a) and five sets of SN curves for torsion and uniaxial tension (b) , (c) , (d) , (e) , and (f) . Influence of Phase Shift between Particular Stress State Components It is well known under fatigue community that the phase shift between particular components of the multiaxial loading are influencing the fatigue life. A special interest among scientists and researchers has a combination of tension-compression or bending and torsion, as it is commonly encountered in a responsible machine elements such as shafts. Many test results have been published in this area. All of them show a significant effect of the phase shift fatigue. Analysed criterion does not have such properties. Under a combination of tension and torsion

 S





[

0 0

0 0 ]

(17)

tt

xx

xy

.

181