Relevant factors affecting the direction of crack propagation in complete contact problems under fretting fatigue

In fatigue problems, an accurate estimation of the propagation direction is important for life prediction. We identify the most relevant factors that affect the crack orientation during the propagation stage of fretting fatigue cracks, arising from complete contacts. Contrary to what initially expected, parameters such as normal load, cyclic bulk load, etc. do not have a noticeable influence on the orientation. However the relative Young's moduli of indenter/specimen materials, the indenter width and the surface coefficient of friction are the most influencing factors. Analyses are performed through the extended finite element method (X-FEM) and an orientation criterion for non-proportional loading proposed by the authors. Experimental fretting fatigue tests confirm the predicted trends. An explanation of this behaviour is also given.The authors gratefully acknowledge the financial support given by the Spanish Ministry of Economy and Competitiveness and the FEDER program through the projects DPI2017-89197-C2-1-R and DPI2017-89197-C2-2-R. The support of the Generalitat Valenciana, Programme PROMETEO 2016/007, is also acknowledged. The authors thank the collaboration of Mr. Francisco Gelardo Rodriguez