Local strain energy density to assess the multiaxial fatigue strength of titanium alloys
Journal Title: Frattura ed Integrità Strutturale - Year 2016, Vol 10, Issue 37
Abstract
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.
Authors and Affiliations
Filippo Berto, Alberto Campagnolo, Torgeir Welo
Keywords
Related Articles
- EP ID EP138732
- DOI 10.3221/IGF-ESIS.37.10
- Views 57
- Downloads 0
Sub-critical cohesive crack propagation with hydro-mechanical coupling and friction
Looking at the long-time behaviour of a dam, it is necessary to assume that the water can penetrate a possible crack washing away some components of the concrete. This type of corrosion reduces the tensile st...
2D size, position and shape definition of defects by B-scan image analysis
The non-destructive evaluation of defects by automatic procedures is of great importance for structural components. Thanks to the developments of the non-contact ultrasonic techniques, the automation of the i...
An ideal model for stress-induced martensitic transformations inshape-memory alloys
In this paper, a novel model for stress-induced martensitic transformations in shape-memory alloysis proposed. Accordingly, the constitutive pseudo-elastic behavior of these materials is described. The modelaccount...
Effects of large amounts of hydrogen on the fatigue crack growth behavior of torsional prestrained carbon steel
The effects of large amounts of hydrogen on the fatigue crack growth properties of torsional prestrained ferritic–pearlitic low-carbon steel were investigated. Hydrogen-precharged specimens were produced by c...
Influence of local stress concentrations on the crack propagation in complex welded components
While a long stable crack propagation phase was observed during experiments of complex welded components, very conservative assessments of the fatigue life were achieved in the past. The difference was explai...