On the prediction of the crack initiation path in fretting fatigue

This work numerically analyses the initial crack path in a fretting fatigue situation. To this end, different criteria to estimate the crack growth (while the crack is less than 57 mu m) have been used. The analysis is performed using a 2D symmetric model of a cylindrical contact fretting problem, consisting of two cylindrical indenters, pressed onto a specimen, and subjected to cyclic axial loading. For the simulation, we use the finite element method (FEM), allowing for crack face contact during the corresponding parts of the fatigue cycle. Three different orientation are used to predict the new crack extension direction in each step of the crack growth simulation. To analyse the different criteria's behaviour, a certain type of fretting fatigue test has been simulated. The experimental results from this test show an initial crack growth with an angle about 60 degrees from the surface and a continuous rotation while growing until it reaches about 90 degrees to the surface, being at this point the crack length longer than 49 mu m. The results obtained with the simulations show that the predicted crack paths vary slightly depending on the criteria used.