Research on the Effect of Elliptical Hole on Localized Cyclic Deformation Near Crack Tip Considering Multi-Parameter

In this paper, a finite element model of single-edge notched compact tensile specimen containing elliptical hole is established considering the effects of elliptical hole geometrical parameters (horizontal spacing d, vertical spacing h, and inclination angle θ) and loading conditions (load ratio R, load amplitude ΔF) in the TC4ELI titanium alloy. The evolution of the shape of the cyclic plastic zone at the crack tip, the response of crack deflection angle ( $${{\theta }_{{\text{c}}}}$$ ) are quantitatively revealed. Study shows that: elliptical hole produce crack path attraction through the stress field gradient effect, attracting crack deflection, and the strength of its action is negatively correlated with the hole-crack tip relative distance (d, h), where the attraction is strongest at h = 0 mm, d = 0.3 mm and θ = 90°. High load amplitude ΔF and high load ratio R significantly increase the crack tip plastic zone area and plastic strain accumulation, and it also exacerbates the crack steering phenomenon. The existence of elliptical hole has an effective effect on crack deflection through the crack steering mechanism, especially at high load ratio and high load amplitude conditions. The reliability of the FE results are verified by in-situ fatigue test using digital image correlation technique.