The notch fatigue behavior of a titanium alloy TC17 in the very high cycle fatigue (VHCF) regime is investigated by a vibration-based bending fatigue test. A complete S-N relation of notched specimens with high resonance frequencies is obtained, covering the lifetime up to 10⁹ cycles, and the fracture surfaces are observed. The results show the TC17 exhibits relatively high fatigue notch sensitivity. Several fatigue crack initiation mechanisms relevant to the notch are then revealed. Furthermore, a notch fatigue prediction model based on a modified theory of critical distance is proposed by introducing a special weight function, which is demonstrated to have good prediction accuracy.

通过基于振动的弯曲疲劳试验研究了 TC17 钛合金在超高周疲劳 (VHCF) 状态下的缺口疲劳行为。获得了具有高共振频率的缺口试样的完整S - N关系，涵盖了长达 10 ⁹个循环的寿命，并观察了断口。结果表明 TC17 表现出相对较高的疲劳缺口敏感性。然后揭示了与缺口相关的几种疲劳裂纹萌生机制。此外，通过引入特殊的权重函数，提出了一种基于修正临界距离理论的缺口疲劳预测模型，并被证明具有良好的预测精度。