Issue 30

V. Chaves et alii, Frattura ed Integrità Strutturale, 30 (2014) 273-281; DOI: 10.3221/IGF-ESIS.30.34

Stage I direction, α (º)

Test

Cycles

Experimental

Chaves

Matake

Carpinteri

Axial

119185 248683 116413 145850 490262 230944 424304 140828 254124 204955 460657 460663 376298 398576 278760 259028 337940 623200 134300 332011

4.0 3.5

17.0 17.0 17.0 17.0

45.0 45.0 45.0 45.0 22.5 22.5 13.3 13.3 13.3 13.3

11.1 11.1 11.1 11.1 11.4 11.4 20.6 20.6 20.6 20.6 26.9 26.9 26.9 26.9 26.9 26.9 33.9 33.9 33.9

10.5 12.0 19.5 17.5 31.5 32.0 32.0 32.0 37.0 40.0 38.5 37.0 36.0 38.0 38.0 43.0 34.0 41.0

Biaxial

5.5 5.5

0.5σ = τ

Biaxial

14.7 14.7 14.7 14.7 21.0 21.0 21.0 21.0 21.0 21.0 28.0 28.0 28.0 28.0

σ = τ

Biaxial 2σ = τ

7.0 7.0 7.0 7.0 7.0 7.0 0.0 0.0 0.0 0.0

Torsion

33.9 Table 1 : Experimental and predicted Stage I crack directions for AISI 304L steel. In-phase tests (R=-1)

S UMMARY AND CONCLUSIONS

A

ISI 304L stainless steel cylindrical specimens were subjected to biaxial loading fatigue tests in order to construct the S – N curves for the material. The in-phase biaxial loading curve was better fitted by an elliptical quadrant than by an elliptical arc. Photographs of the cracks on the outer surface of broken specimens taken with a light microscope were used to measure the angle at the crack initiation zone (Stage I), which was found to be close to the direction of Mode I. A comparison of the measured angle with predicted values obtained by using the models of Chaves et al., Matake and McDiarmid, and Carpinteri and Spagnoli, revealed that the last provided the best results in this respect.

A CKNOWLEDGEMENTS

T

he authors would like to thank the Spanish Ministry of Education for its financial support through grant DPI2011-27019.

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