基于微结构的多轴低周疲劳寿命预测方法

Microstructure-based Multiaxial LCF Life Prediction Method

采用TEM分析了单轴、比例及非比例低周疲劳载荷下钛合金BT9的位错及其亚结构。结果表明,在同一等效应变强度下,位错密度随载荷非比例程度增大而增大。给出了基于疲劳位错密度均值的非比例参量和具有明确微观物理意义的疲劳损伤参量。建立了新的低周疲劳寿命预测模型,且寿命预测精度进一步提高。

The dislocation and its substructures of titanium alloy BT9 under uniaxial, proportional, and non-proportional low cycle fatigue（LCF） were analyzed by using transverse electromagnetic mode（TEM）. It is observed that dislocation density increases with the increasing degree of loading nonproportionality under the same strain intensity. A new parameter of non-proportionality based on mean dislocation density and a fatigue damage parameter with a clear microphysical meaning were introduced. A new LCF life prediction model was proposed. The fatigue life prediction precision based on the new model is further improved.