Extension of linear elastic strain energy density approach to high temperature fatigue and a synthesis of Cu-Be alloy experimental tests

Abstract

The present paper summarizes the results from uniaxial-tension stress-controlled fatigue tests performed at different temperatures up to 650°C on Cu-Be specimens. Two geometries are considered: hourglass shaped and plates weakened by a central hole (Cu-Be alloy). The motivation of the present work is that, at the best of authors' knowledge, only a limited number of papers on these alloys under high-temperature fatigue are available in the literature and no results deal with notched components. The Cu-Be specimens fatigue data are re-analyzed in terms of the mean value of the Strain Energy Density (SED) averaged over a control volume. Thanks to the SED approach it is possible to summarize in a single scatter-band all the fatigue data, independently of the specimen geometry.

Advanced Materials for Applications at High Temperature: Fatigue Assessment by Means of Local Strain Energy Density

“…Other attempts to extend such a method to high temperature have been made by the present authors in the last years, considering also other high-temperature effect such as creep. [13][14][15][16][17] Some authors have gone further on this topic, investigating the interactive creep-fatigue crack growth, obtaining very good results. [18] Kawagoishi and coworkers [19,20] investigated the strength of nickel-base superalloy Inconel 718 under rotating banding loading at room temperature and 500 C in air.…”

A Review of the Fatigue Strength of Load Carrying Shear Welded Joints

“…Some Recent Studies interesting were focused on the effect of the voltages on the SED values (Ferro et al, 2006;Ferro, 2012;2014;Ferro et al, 2016a;2016c;Ferro and Berto, 2016) and the matter is very important for the practical applications and shall be taken into account also in the future work. In addition, some recent developments can be found in Refs (Gallo et al, 2016a;Berto and Gallo, 2015;Gallo and Berto, 2015c;Berto et al, 2014a;2014b), which deals with high temperature and the fatigue of metal.…”

Evaluation of the strain energy density control volume for a nanoscale singular stress field

“…Other important advantages can be achieved by using the SED approach. The most relevant are the following: The scale effect is considered in the SED formulation; It can be applied and defined for mode II, III and mixed mode condition; It overcomes the problem tied to the different NSIF units of measure in the case of different notch opening angles; In case of very thin structures, T‐stress is taken into account in the method; It directly includes three‐dimensional effect and out‐of‐plane singularities; It has been recently employed to assess high temperature fatigue of notched components, showing enormous potentialities also when non‐linear effects are taking place …”

“…• It can be applied and defined for mode II, III and mixed mode condition; • It overcomes the problem tied to the different NSIF units of measure in the case of different notch opening angles; • In case of very thin structures, T-stress is taken into account in the method; • It directly includes three-dimensional effect and outof-plane singularities; • It has been recently employed to assess high temperature fatigue of notched components, showing enormous potentialities also when non-linear effects are taking place. [36][37][38][39][40][41][42][43][44][45] Under the hypothesis that all the material inhomogeneities can be averaged, the SED approach showed to be a powerful tool both for static and fatigue strength assessment of notched and welded structures.…”