A New Evaluation Method to Calculate Crack Initiation Limit with Modified Crack Aspect Ratios in Notched Specimen of Carbon Steels

Abstract:

Aspect ratio is a key factor to calculate stress intensity factor (SIF) K using fracture mechanics. While cracks are approximated to be semi-circle or semi-ellipse for simply evaluation, their shapes are changed by stress concentration source. In this study, a new method to modify aspect ratio of a crack at a notch root is proposed. Modified aspect ratio in this method succeeded to decrease prediction error of fatigue crack initiation stress, σ_w1 which was calculated using experimental value.

• Periodical: Applied Mechanics and Materials (Volume 563)
• Pages: 80-84
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.563.80
• Online since: May 2014
• Authors: Takahiro Matsueda*
• Keywords: Aspect Ratio, Carbon Steels, Crack, Fatigue Limit, Notch, Stress Intensity Factor (SIF)

References

[1] Y. Murakami, Analysis of stress intensity factors of Mode I, II and III for inclined surface cracks of arbitrary shape, Engineering Fracture Mechanics. 22, 1 (1985) 101-114.

DOI: 10.1016/0013-7944(85)90163-8

[2] Y. Murakami, M. Endo, Effects of defects, inclusions and inhomogeneities on fatigue strength, International Journal of Fatigue. 16 (1994) 163-182.

DOI: 10.1016/0142-1123(94)90001-9

[3] J. C. Lee, T. N. Farris, L. M. Keer, Stress intensity factors for cracks of arbitrary shape near an interfacial boundary, Engineering Fracture Mechanics. 21, 1 (1987) 27-41.

DOI: 10.1016/0013-7944(87)90003-8

[4] N. Noda, K. Kobayashi, M. Yagishita, Variation of mixed modes stress intensity factors of an inclined semi-elliptical surface crack, International Journal of Fracture. 100 (1999) 207–225.

[5] W.O. Soboyejo, J.F. Knott, An investigation of crack closure and the propagation of semi-elliptical fatigue cracks in QIN (HY80) pressure vessel steel, International Journal of Fatigue. 17, 8 (1995) 577-581.

DOI: 10.1016/0142-1123(96)81217-5

[6] K. Tanaka, Y. Nakai, O Maekawa, Microscopic study of fatigue crack initiation and early propagation in smooth specimen of low carbon steel, Zairyo. 31, 343 (1982) 66-72. (in Japanese).

[7] K. Takao, H. Nisitani, Relation between characteristics of crack initiation of metals and their notch sensitive in fatigue, Zairyo. 39, 409 (1987) 1060-1064. (in Japanese).

[8] T. Matsueda, H. Noguchi, Fatigue limit evaluation of blunt-notched specimen using ΔKth value of Small Crack, Procedia Engineering. 10 (2011) 1023-1028.

DOI: 10.1016/j.proeng.2011.04.168

[9] Y. Verreman, N. Limodin, Fatigue notch factor and short crack propagation, Engineering Fracture Mechanics. 75 (2008) 1320–1335.

DOI: 10.1016/j.engfracmech.2007.07.005

[10] H. Noguchi, Y. Aono, Application limit of linear notch mechanics, Transaction of the Japan Society of Mechanical Engineers. A. 66, 589 (2000) 78-85. (in Japanese).

[11] N. Noda, M. Sera, Y. Takase, Stress concentration factors for round and flat test specimens with notches, International Journal of Fatigue. 17, 3 (1995) 163-178.

DOI: 10.1016/0142-1123(95)98937-x

[12] Y. Murakami. et. al, Stress intensity factor hand book Vol. 2, Pergamon Press, UK, 1987, pp.725-27, 802-03.

[13] Y. Murakami, Metal fatigue: effects of small defects and nonmetallic inclusions, Elsevier, UK, (2002).

[14] H. Nisitani, H. Horio, H. Noguchi, Fatigue strength in 3 kinds of carbon steels having nearly equal sizes of ferrite, Transaction of the Japan Society of Mechanical Engineers. A. 56, 524 (1990) 687-693. (in Japanese).

DOI: 10.1299/kikaia.56.687

[15] ASTM Designation, Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness, ASTM international E140-12bε1, USA, (2013).

DOI: 10.1520/e0140-12br19e01