钛合金疲劳裂纹扩展速率试验及预报方法

本文针对深海载人潜水器耐压壳用钛合金,开展疲劳性能试验研究,得到该类型钛合金的室温断裂韧性,载荷比R=0.1下的疲劳裂纹扩展门槛值及疲劳裂纹扩展速率,基于选用的疲劳裂纹扩展预报模型,对载荷比R=0.1下的钛合金疲劳裂纹扩展行为进行了预报研究。结果表明:在载荷比不变的前提下,应力强度因子范围是疲劳裂纹扩展速率的主要影响因素,应力强度因子范围的增加会导致疲劳裂纹扩展速率增加;考虑小裂纹效应的疲劳裂纹扩展预报模型可对钛合金的疲劳裂纹扩展行为进行准确预报。

Test and prediction of fatigue crack growth rate of titanium alloy materials

In this paper, the fatigue performance test of titanium alloy materials for pressure-resistant shells of deep-sea manned submersibles is carried out. The fracture toughness of titanium alloy and the fatigue crack growth threshold and fatigue crack growth rate curve at load ratio R=0.1 are obtained. Finally, using the fatigue crack propagation prediction model of titanium alloy material, the fatigue crack propagation behavior of titanium alloy at load ratio R=0.1 was predicted. The results show that the stress intensity factor range is the main influencing factor of fatigue crack growth rate under the premise of constant load ratio. The increase of stress intensity factor range will lead to the increase of fatigue crack growth rate. The fatigue crack propagation prediction model which considering small fatigue crack effect can predict of fatigue crack growth behavior of titanium alloys accurately.