PSI - Issue 2_A

Hide-aki Nishikawa et al. / Procedia Structural Integrity 2 (2016) 3002–3009 Author name / Structural Integrity Procedia 00 (2016) 000–000

3008

7

c

b

a

σ = σ min (reference image)

σ = σ min + 0.4 ∆σ

σ = σ min + 0.3 ∆σ

f

e

d

100 μm

σ = σ min + 0.5 ∆σ

σ = σ min + 0.6 ∆σ

σ = σ min + ∆σ = σ max

-0.002

0.012

Loading direction

Strain in vertical direction (-)

Fig. 6. Small fatigue crack opening behavior observed with DIC technique.

400

400

Material B, σ a = 280 MPa, l =0.3mm

Material B, σ a = 280 MPa, l =0.8mm

a

b

300

300

Strain gage

Strain gage

200

200

DIC strain

DIC strain

100

100

0

0

σ op

σ op

Strain measurement area

-100

-100

Strain measurement area

Stress (MPa)

Stress (MPa)

-200

-200

-300

-300

100 μm

100 μm

-400

-400

-0.005

0

0.005

0.01

0.015

0.02

-0.005

0

0.005

0.01

0.015

0.02

Strain (-)

Strain (-)

Fig. 7. Relationship between stress and crack opening strain measured with DIC technique for crack length of (a) 0.3 mm and (b) 0.8 mm.

0.30%

σ a [MPa]

σ m [MPa]

TP

280 240 210 240 210 340 320 280 280 280 480 420 400

0 0 0

0.25%

A

0.20%

100 130

0.15%

0 0 0

ε eq (-)

B

0.10%

120 120

0.05%

0 0

C

300

0.00%

0.00% 0.10% 0.20% 0.30% 0.40%

ε eff (-)

Fig. 8. Relationship between ε eq and ε eff measured with DIC technique.