PSI - Issue 19

Kiyotaka Masaki / Procedia Structural Integrity 19 (2019) 168–174

171

Kiyotaka MASAKI/ Structural Integrity Procedia 00 (2019) 000–000

4

a

b

10 3 250 300 Stress Amplitude  a , MPa AZ31 100 150 200 250 300 Stress Amplitude  a , MPa AZ80 10 4 50 100 150 200

300

AZ61

6mm 5mm

6mm 5mm

200 250

10 3 Stress Amplitude  a , MPa 10 4 50 100 150

10 5

10 6

10 7

10 8

10 5

10 6

10 7

10 8

10 9

Number of cycles to failure N f , cycles

Number of cycles to failure N f , cycles

c

6mm 5mm

10 3 10 4 10 5 10 6 10 7 10 8 10 9 50 Number of cycles to failure N f , cycles

Fig. 3. S-N curves of materials (a) AZ31; (b) AZ61; (c) AZ80.

4. Discussion

4.1. Survey results of literature data

The correlation between fatigue limit and static strength which are tensile strength or compression strength are suggested some past reports. For example, Shiozawa et al. reported that the first horizontal stress in the two-step bending S-N curve is equal to the compressive 0.2 % proof stress of AZ31, AZ61 and AZ80 alloy (Shiozawa and

a

b

250

250

Bending Loading (R=-1)

Bending Loading (R=-1)

 w = 0.54  0.2T

150 200

150 200

 w =  0.2C

 w = 0.87  0.2C

 w = 0.38  BT

100 Fatigue limit  w , MPa

100 200 300 400 500 Fatigue limit  w , MPa Static strength (Compressive)  BC ,  0.2C , MPa  w -  0.2C  w -  BC  w = 0.37  BC 0 50 100

0 100 200 300 400 500 0 50 Static strength (Tensile)  BT ,  0.2T , MPa  w -  0.2T  w -  BT

Fig. 4 Relationships between fatigue limit and static strength (a) tensile; (b) compressive.