Issue 47

D. Rigon et alii, Frattura ed Integrità Strutturale, 47 (2019) 334-347; DOI: 10.3221/IGF-ESIS.47.25

49 49.5 50 50.5 51 51.5 52 52.5 53

42

a)

b)

f L

= 10 Hz

f L

= 25 Hz

= 190 MPa

 an N f

= 110 MPa

 an N f

= 7.82ꞏ10 3 cycles

= 2.71ꞏ10 5 cycles

41.5

∂T/∂t = -4.81°C/s

41

∂T/∂t = -2.02°C/s

T max [°C]

T max [°C]

40.5

r n

= 3 mm

r n

= 3 mm

40

-0.5 -0.25 0 0.25 0.5 0.75 1 t=t*

-0.5 -0.25 0 0.25 0.5 0.75 1 t=t*

t [s]

t [s]

32.8 33 33.2 33.4 33.6 33.8 34 35.5 36 36.5 37 37.5 38 38.5

40.5

c)

d)

f L

= 15 Hz

f L

= 10 Hz

= 120 MPa

 an N f

= 150 MPa

 an N f

40

= 7.68 ꞏ10 4 cycles

= 1.67ꞏ10 4 cycles

39.5

∂T/∂t = -2.80°C/s

∂T/∂t = -1.67°C/s

T max [°C]

T max [°C]

39

38.5

r n

= 1 mm

r n

= 1 mm

38

-0.5 -0.25 0 0.25 0.5 0.75 1 t=t*

-0.5 -0.25 0 0.25 0.5 0.75 1 t=t*

t [s]

t [s]

39.5

e)

f)

f L

= 35 Hz

f L

= 5 Hz

= 100 MPa

 an N f

= 190 MPa

 an N f

39

= 1.35ꞏ10 5 cycles

= 8.17ꞏ10 3 cycles

38.5

∂T/∂t = -4.11°C/s

∂T/∂t = -1.75°C/s

T max [°C]

T max [°C]

38

37.5

= 0.5 mm

r n

r n

= 0.5 mm

37

-0.5 -0.25 0 0.25 0.5 0.75 1 t=t*

-1 -0.5 0 0.5 1 1.5 2 t=t*

t [s]

t [s]

Figure 6 : Heat energy distributions at the notch tip: (a,b,) r n

=3 mm, σ an

=170 MPa, N f

=1.85·10 4 cycles; (c,d) r n

=1 mm, σ an

=150 MPa,

=1.67·10 4 cycles; (e,f) r n

=0.5 mm, σ an

=100 MPa, N f

=1.35·10 5 cycles

N f

339