PSI - Issue 66

Grzegorz Glodek et al. / Procedia Structural Integrity 66 (2024) 331–336 Author name / Structural Integrity Procedia 00 (2025) 000 – 000

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Figure 1 Assembled fretting fatigue test set-up positioned in the fatigue bench.

2.2. Finite element model A 2D finite element (FE) model was developed to evaluate the contact stress distribution within the test setup, as illustrated in Figure 2. The fixture was constrained at the top to prevent any movements, and load was applied to the bottom of the specimen. The model was meshed using quadrilateral, 4-node, plane strain elements with reduced integration (CPE4R). Fine mesh size of 10µm combined with structured mesh control were used at the contact interface between the sample and the pads in order to ensure accurate stress calculations. Elasto-plastic material properties were used in order to account for the localized plastic deformations at the contact edges. The contact interaction was defined using Lagrange multiplier for the tangential contact behavior and “hard” contact with Augmented Lagrange constraint enforcement method for the normal behavior. The coefficient of friction (COF), experimentally determined to be 0.55, was used to simulate the frictional effects at the contact interface. 3. Results and Discussion 3.1. Stress distributions Figure 3 (a) illustrates the contact stress distribution for a test conducted at a maximum fatigue load of 18.0 kN. A high peak in tangential stress is observed at the leading edge of contact which, in combination with a high value of von Mises stress, points to this area as a likely location of crack initiation. The shear stress distribution confirms the presence of stick-slip conditions throughout the test, which are known to represent the most damaging scenario under fretting fatigue conditions [9]. The results align with stress distribution patterns reported in the literature for comparable models, confirming the accuracy and reliability of the developed finite element model [10,11]. Figure 3 (b) shows the maximum in-plane principal stress contour plot of the dovetail portion of the specimen. In addition to the stress concentration at the contact edge, a significant stress field is observed along the curved edges above the neck region of the specimen. This suggests that, especially in the presence of surface or subsurface defects, failure could potentially occur in these regions rather than at the contact interface.