高温多轴变幅疲劳损伤累积

为进行高温多轴变幅疲劳寿命预测,以应力幅作为损伤变量,采用经典的Chaboche模型进行多轴疲劳损伤计算.多轴加载下等效应力的确定是根据单轴加载下的本构关系,利用多轴等效应变求出等效应力.修正Chaboche疲劳累积损伤模型中应力指数表达式的形式,根据Chaboche损伤累积模型,求解变幅加载下的疲劳损伤.推导出多级加载的Chaboche疲劳损伤累积公式,将其用于变幅加载块的疲劳损伤估算.寿命预测结果与试验结果接近,误差基本在2倍因子之内,说明了寿命估算方法的可行性.

Fatigue Damage Accumulation Amplitude Loading at Under Multiaxial Variable High Temperature

To predict fatigue life under multiaxial variable amplitude loading at high temperature,the stress amplitude was used as damage variable and multiaxial fatigue damage was computed with classical Chaboche model.Determination of equivalent stress under multiaxial loading was based on the constitutive relationship under uniaxial loading and the equivalent stress was obtained with multiaxial equivalent strain.The expression form of stress index in the Chaboche fatigue accumulated damage model was revised.Fatigue damage under variable amplitude loading was solved according to the Chaboche damage accumulation model.Chaboche fatigue damage cumulative formula under multistage loading was deduced and applied to fatigue damage evaluation under variable amplitude loading.The life prediction results close to the experimental results.The error is basic within 2 time factors,indicating the feasibility of the life estimation method.