Fretting fatigue crack propagation rate under variable loading conditions
Fretting fatigue experiments aim to represent industrial problems and most of them endure variable loading. Being able to assess lifetime of assemblies, especially for low propagation rate conditions, is essential as experimental validation is often too expensive. Both experimental and numerical a...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Gruppo Italiano Frattura
2016-01-01
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| Series: | Fracture and Structural Integrity |
| Subjects: | |
| Online Access: | http://www.gruppofrattura.it/pdf/rivista/numero35/numero_35_art_27.pdf |
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| Summary: | Fretting fatigue experiments aim to represent industrial problems and most of them endure variable
loading. Being able to assess lifetime of assemblies, especially for low propagation rate conditions, is essential as
experimental validation is often too expensive. Both experimental and numerical approaches are proposed to
follow the crack propagation rate of steel on steel cylinder/plane fretting fatigue contact submitted to variable
loading conditions.
An original experimental monitoring has been implemented on the fretting-fatigue test device to observe crack
propagation using a potential drop technique. A calibration curve relating crack length and electrical potential
was established for the studied contact. It allows direct knowledge of the crack length and crack propagation
rate. It was applied to mixed load test showing crack arrest for the last loading condition.
To explain this behavior, a 2-dimensional FE modeling was implemented to simulate the complexes multi-axial
contact stressing. The crack propagation rate was formalized using an effective stress intensity factor amplitude
ΔKeff coupled with Paris law of the material. The crack arrest condition for a given loading was related to ΔKeff
along the expected crack path crossing the material crack arrest threshold ΔK0. The failure was related to ΔKeff
reaching the critical stress intensity factor KIC. A good correlation with experiments was observed allowing to
predict the crack arrest condition although the model tends to overestimate the final crack length extension. |
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| ISSN: | 1971-8993 1971-8993 |