Local strain energy density to assess the multiaxial fatigue strength of titanium alloys
The present paper investigates the multiaxial fatigue strength of sharp V-notched components made of titanium grade 5 alloy (Ti-6Al-4V). Axisymmetric notched specimens have been tested under combined tension and torsion fatigue loadings, both proportional and non-proportional, taking into account...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Gruppo Italiano Frattura
2016-07-01
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| Series: | Fracture and Structural Integrity |
| Subjects: | |
| Online Access: | http://www.gruppofrattura.it/pdf/rivista/numero37/numero_37_art_10.pdf |
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| Summary: | The present paper investigates the multiaxial fatigue strength of sharp V-notched components
made of titanium grade 5 alloy (Ti-6Al-4V). Axisymmetric notched specimens have been tested under combined
tension and torsion fatigue loadings, both proportional and non-proportional, taking into account different
nominal load ratios (R = -1 and 0). All tested samples have a notch root radius about equal to 0.1 mm, a notch
depth of 6 mm and an opening angle of 90 degrees. The fatigue results obtained by applying multiaxial loadings
are discussed together with those related to pure tension and pure torsion experimental fatigue tests, carried out
on both smooth and notched specimens at load ratios R ranging between -3 and 0.5.
Altogether, more than 250 fatigue results (19 S-N curves) are examined, first on the basis of nominal stress
amplitudes referred to the net area and secondly by means of the strain energy density averaged over a control
volume embracing the V-notch tip. The effect of the loading mode on the control volume size has been
analysed, highlighting a wide difference in the notch sensitivity of the considered material under tension and
torsion loadings. Accordingly, the control radius of the considered titanium alloy (Ti-6Al-4V) is found to be
strongly affected by the loading mode. |
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| ISSN: | 1971-8993 1971-8993 |