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A STUDY ON FATIGUE CRACK GROWTH UNDER OUT-OF-PHASE COMBINED LOADINGS |
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| Authors: | I Ohkawa H Takahashi M Moriwaki M Misumi |
| Affiliation: | Department of Mechanical Engineering, College of Engineering, Hosei University, 3-7-2 Kajino-cho, Koganei-shi, Tokyo 184, Japan;Graduate School, Hosei University, 3–7–2 Kajino-cho, Koganei-shi, Tokyo 184, Japan;Department of Mechanical Engineering, Faculty of Engineering, Seikei University, 3-3-1 Kita-machi Kichijoji, Musashino-shi, Tokyo 180, Japan |
| Abstract: | Abstract— Fatigue tests were performed on thin-walled tubular specimens of S45C steel under tension-compression, pure torsion, in-phase and out-of-phase axial-torsional loadings. The relationship between cracking behaviour and stress components on the crack plane was investigated. Measurement of microcrack density showed that microcracking was governed predominantly by the shear stress amplitude acting on the crack plane for all loading conditions. The failure crack was formed by coalescence of many cracks initiated near the maximum shear planes. The cracks grew turning their orientation to the direction perpendicular to the maximum normal stress. The transition of crack orientation occurred at relatively longer crack lengths at a higher stress ratio. The crack growth behaviour for all loading modes can be correlated using an equivalent strain intensity parameter based on shear and normal strains on the crack plane. |
| Keywords: | Multiaxial fatigue Out-of-phase loading Carbon steel Crack orientation Crack growth rate Equivalent strain intensity range |