Advanced methodology for fretting fatigue assessment of metallic structural components

The present Ph.D. Thesis deals with the analysis of metallic structural components subject to fretting fatigue in partial slip regime. An analytical methodology for fretting fatigue assessment of structural components is proposed. Such a methodology allows to evaluate both the initial crack path and the lifetime of metallic structures under fretting fatigue elastic partial slip loading conditions in high-cycle fatigue. The proposed methodology consists in the joint application of the multiaxial fatigue criterion by Carpinteri et al. together with the non-local approach (named Critical Direction Method) by Araújo et al. The philosophy related to the theory of the Critical Distance by Taylor is also taken into account in the procedure. The stress field induced into two bodies in contact subject to fretting fatigue is analysed in Chapter 2, since it represents an input data for the methodology. Firstly, the damage process associated with fretting is described, by even exploiting the concept of fretting map. Subsequently, the main methodologies available in the literature to analyse fretting fatigue problems are briefly reviewed. Finally, the analytical formulation implemented in the proposed methodology is detailed. Chapter 3 is devoted to the description of the advanced analytical methodology proposed in the present Ph.D. Thesis for fretting fatigue assessment of structural components. In particular, both the Critical Direction Method by Araújo et al., the theory of the Critical Distance by Taylor, and the Carpinteri et al. criterion for fretting fatigue are described. Then, the steps of the advanced methodology proposed in the present Ph.D. Thesis are detailed. Chapter 4 deals with the validation of the proposed analytical methodology. In more detail, ten different experimental campaigns available in the literature and related to fretting fatigue tests in partial slip conditions are examined. Eight different materials, that is, four aluminium alloys, one titanium alloy and three steels, are analysed. The results obtained in terms of both crack path orientation and fatigue life are described and compared to the experimental ones available in the literature, for each experimental campaign examined. Finally, conclusions are summarised in Chapter 5.