Initial orientation of the fretting fatigue cracks in shrink-fit connection specimens
The bending configuration of shrink-fitted connection fretting fatigue tests causes a fluctuation in the contact pressure and in turn a more favourable condition for shear, rather than tensile, crack initiation. According to the classification type I (shear) and type II (tensile) fretting cracks, ty...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
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Gruppo Italiano Frattura
2019-04-01
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| Series: | Fracture and Structural Integrity |
| Subjects: | |
| Online Access: | https://www.fracturae.com/index.php/fis/article/view/2288/2430 |
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| Summary: | The bending configuration of shrink-fitted connection fretting fatigue tests causes a fluctuation in the contact pressure and in turn a more favourable condition for shear, rather than tensile, crack initiation. According to the classification type I (shear) and type II (tensile) fretting cracks, type II was only observed in the tests with no surface enhancement, which experienced the lowest fretting strength and thus a reduced pressure fluctuation effect. The crack initial direction was predicted as the critical plane orientation undergoing the maximum Fatemi-Socie (FS) stress parameter, for the shallow type I shear cracks. A significant result is that if the critical plane is searched at the fretting hot-spot, an incorrect outward direction is obtained, since the orthogonal direction, with the same shear stress amplitude, experiences a more compressive maximum normal stress. Conversely, with the application of the Point Method, taking the stress location at half the critical distance and by following the potential critical plane, a higher shear stress along the inward direction is obtained. The more compressive stress below the contact can therefore be compensated, and consequently the inward shallow direction is correctly predicted. |
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| ISSN: | 1971-8993 |