Issue 35

C. Gandiolle et alii, Frattura ed Integrità Strutturale, 35 (2016) 232-241; DOI: 10.3221/IGF-ESIS.35.27 236 Experimental identification of fretting fatigue crack propagation rate The potential drop technique was applied on the following solicitation: P, σ F,moy /σ y,flat =0.78, R F =0.85, Q*/P=0.30. Fig. 4 plots the obtained potential and the crack propagation calculated from the calibration curve. The crack nucleates around N CN =10 5 cycles, and propagates slowly until b=300µm. then the propagation rate increases until failure at N T =1.73x10 6 cycles for a final crack length of b T =2.8 mm. The propagation life is easily deduced: N P =N T -N CN =1.63x10 6 cycles. The crack initiation time is less than 6% of the total lifetime of the contact. The crack initiation life will thus be neglected in the lifetime prediction. Figure 4 : (a) Potential as a function of the number of cycles, (b) crack length as a function of the number of cycles calculated with the calibration curve. (R=4.6mm, P, σ F,moy /σ y,flat =0.78, R F =0.85, Q*/P=0.30). P REDICTION OF CRACK PROPAGATION RATE Finite Element analysis inite element (FE) analysis was carried out using Abaqus 6.10 software. A 2D plain strain model of the fretting fatigue test was generated (Fig. 5a). The dimensions and boundary conditions matched the parameters of the physical experiment. The model was meshed with CPE3-type linear triangular elements, except in the contact zone where CPE4R-type linear quadrilateral elements were used; this zone was also meshed more densely than the other regions (5µm squares). F