疲劳累积损伤理论的适用性研究

A Study on the Applicability of Fatigue Cumulative Damage Theory

疲劳累积损伤理论是结构疲劳寿命分析的基础。本文首先推导有代表性的疲劳累积损伤理论在二级加载模式下的预测模型;然后通过试验数据析了在二级加载下金属疲劳累积损伤理论的适用性。分析结果表明:各模型在不同加载方式下对结果预测的准确性差别较大。Manson模型和韧性耗散模型等非线性模型比较好地改善了Miner理论预测的精度,并且Manson模型对于旋转弯曲的钢材料具有更好的适用性;而对于受拉压的铝合金材料,韧性耗散模型具有更好的适用性。Miner理论、韧性耗散模型和Manson模型在用于随机谱的预测时,预测的误差有减小的趋势;而Carten-Dolar模型预测的误差有增大的趋势。

Fatigue cumulative damage theory is the foundation of the analysis of structure fatigue life. This article first analyzed the fatigue cumulative damage theories which is representative and deduced the forecasting formulas of these models under the loading of two levels; then analyzed the applicability of these fatigue cumulative damage theories through the experiment data under the loading of two levels. The result indicated that：there is much difference in these models when they are used in estimating under different kind of loading.Manson model and the toughness degradation model which is all non-linear model has a better applicability regarding two levels loading environment;and Manson model has a better applicability for steel material under circumrotation and bending;but for the aluminum metal alloy under pulling and pressing, the toughness degradation model has a better applicability. While using the Miner theory,the toughness degradation model and the Manson model for the estimating under the loading of random spectrum, the forecasting error will become smaller;but the forecasting error of the Carten-Dolar model has the trend of becoming larger.