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为评价极端循环载荷下的服役性能,采用轴向名义应变控制法研究了2124-T851铝合金厚板短横向超低周疲劳(ELCF)行为。研究表明:该合金在ELCF过程中表现出持续稳定的循环软化特性,软化速率与名义应变幅Δεn/2呈幂函数关系;由Δεn/2表征的Manson-Coffin公式能准确地预测该合金的ELCF寿命。断口分析表明:短横向加载的静态断裂和ELCF断裂方向均趋于长横向,且随Δεn/2减小,断裂模式由切断型逐渐转变为正断型;ELCF微观形貌总体为韧窝断口+挤压平面,且仅在Δεn/2降至0.4%时出现疲劳条带。
In order to evaluate the serviceability under extreme cyclic loading, axial short-period ultra-low cycle fatigue (ELCF) behavior of 2124-T851 aluminum alloy plate was investigated by using axial nominal strain control method. The results show that the alloy exhibits a continuous and stable cyclic softening behavior during ELCF. The softening rate has a power function relationship with the nominal strain amplitude Δεn / 2. The Manson-Coffin formula characterized by Δεn / 2 can accurately predict the ELCF life. Fracture analysis shows that both the static fault and the ELCF fracture direction tend to be long and transverse in the short transverse direction and decrease with Δεn / 2, and the fracture mode gradually changes from the fault type to the normal fault type. The ELCF microscopic morphology is generally dimple fracture + The plane is squeezed and the fatigue band appears only when Δεn / 2 drops to 0.4%.