一种新的多轴高周疲劳模型

A New High-cycle Fatigue Model under Multiaxial Loading

将疲劳强度以上加载等效为塑性应变.建立了塑性应变与加载应力呈线性关系的表达式,由此得到循环加栽的塑性应变能。该塑性应变能使材料微观组织结构发生不可逆变化而引起等效宏观应力。假定该应力符合一种特定的分布函数.导出其最大应力与外加应力叠加达到材料本征断裂应力时的裂纹成核寿命.从而并由微裂纹引起上述两部分应力变化,得到继续加载直至宏观裂纹出现的疲劳寿命。所建立的多轴疲劳寿命公式由3个材料参数表达,并通过单轴疲劳试验数据确定。初步研究表明:该模型对所引用的多轴疲劳试验数据有很好的预测能力。

The present multiaxial fatigue model in high-cycle was assumed that the plastic detormatlon was linear to applied fatigue loading that was above fatigue limits, and the plastic strain energy could be calculated. The microscopic structure of material would be permanently change and produce equivalent macroscopic stress due to plastic energy. Given a distribution function of the stress, derive the crack nucleation life when the superposition of maximum equivalent macroscopic stress and applied loading stress achieves the material＇s intrinsic fracture stress, consider in the changes of the above two stresses caused by microcrack, the fatigue life of continue to loading until the macroscopic crack appears could be worked out. The established multiaxial fatigue life prediction formula contains three material parameters, and through uniaxial fatigue experiment data to determine. Preliminary research indicated that the model had a satisfied prediction ability for the referenced multiaxial fatigue test data.