Issue 62

A. S. Yankin et alii, Frattura ed Integrità Strutturale, 62 (2022) 180-193; DOI: 10.3221/IGF-ESIS.62.13

max

     max min mean min

I

I

I

I

I

0

2

2

1

1

1

mean

2





I

(10)

2

 1

mean

   1 A

A I

4 2

4

2 B

Under static tension:

max

    min max min

I

I

I

I

0

2

2

1

1

1 3

mean

mean

2

 ;







I

I

(11)

1

2

1

1 1

       1 A A

2

2







3

3

B

B

B

where τ b is the ultimate shear strength. Under uniaxial cyclic symmetric torsion:

min

     mean max min mean

I

I

I

I

I

0

2

2

1

1

1

max

2

 a



I

(12)

2

2

 2 a

2

   1 A

A

     0 ' 2 b f N

3

3

2

where τ′ f , b 0 are material parameters determined from the fatigue curve for symmetrical cyclic torsion. Under uniaxial cyclic symmetric tension-compression:

min

   mean mean

I

I

I

0

2

2

1

1 3

   min max

max

2

 a

 a



I

I

I

(13)

;

1

1

2

 a

1

1

     1 A A



a

1

1

  N

  2 N

  N

b

b

b

 ' 3 2

 '

 ' 3 2

0

1

0

f

f

f

where σ′ f , b 1 are material parameters determined from the fatigue curve at symmetrical cyclic tension-compression. As a result, the model looks like this:

   

   

  

  

max

min

mean

max min





I

I

I

I

I

1

1

1 1

mean

2

2

  2

1

1



 



I

1

(14)

     0 ' 2 b f N

1

  2 N

  N

b

b

2

2 B





2



 '

 ' 3 2

3

1

0

B

B

f

f

183