13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Introduction of a reverse simulation approach to identify the fatigue SIF crack arrest threshold from fretting cracking experiments Alix de Pannemaecker1&2,*, Siegfried Fouvry1, Jean-Yves Buffière² 1 LTDS, Ecole Centrale Lyon, 69134 Ecully, France 2 MATEIS, INSA Lyon, 69100 Villeurbanne, France * Corresponding author: alix.de-pannemaecker@ec-lyon.fr Abstract Fretting is a small amplitude oscillatory movement appearing between two contacting surfaces subjected to vibrations. This phenomenon may generate crack growth propagation. The aim of the present work is to estimate the ΔKIth (Crack arrest stress intensity factor) related to the crack arrest condition of a material subjected to partial slip fretting loadings by coupling experimental results and numerical simulations. The study is limited to cylinder/plane models TA6V/Al-alloys. In this approach, fretting tests are first performed for each configuration to obtain the crack length as a function of fretting cycles in order to establish the length of the arrested crack. Then an automatic program based on FEM simulations of the experimental test is developed to estimate the stress intensity factor corresponding to the crack arrest. Using a reverse analysis, the ΔKth corresponding to the crack arrest condition is identified and different materials are compared. Keywords Fretting tests, Fatigue crack arrest, Crack closing, Stress intensity factor 1. Introduction Araujo et al. [1] demonstrated that the fretting fatigue endurance can be formalized using a short crack arrest methodology. This approach has been adopted in [2] to estimate the crack arrest boundary in the fretting fatigue map approach. Such analysis consists in computing the evolution of the stress intensity factor as a function of the crack length and to evaluate if this K-factor loading path intercepts or not the short crack arrest boundary. If the ΔK loading path overpasses this boundary, then a fretting fatigue failure is expected. Note that the short crack arrest boundary is approximated using either KT or El Haddad formalism. Such a methodology usually considers a crack localized at the contact border and perpendicular to the contact surface. However, experimental results show that the crack path below the interface is more complex and usually displays an oblique angle oriented toward the inner part of the contact. A major question is to know if the normal crack approximation is relevant to describe the real crack path evolution. A second aspect concerns the short crack methodology which is usually applied to approximate the crack arrest condition. In this research work, we consider an original reverse approach which consists in estimating the ΔKIth related to the studied material by applying a reverse identification method of our experimental results.
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