摘要
零件的疲劳破坏是一个损伤逐步累积、承载能力逐步下降的过程,其疲劳强度随其承受的载荷和频次而不断衰减.通过研究疲劳过程中材料剩余强度衰减退化的规律,从疲劳损伤的定义出发,把剩余强度退化通过一个衰减系数引入到损伤的定义中,提出考虑材料强度性能退化的非线性累积损伤模型来修正Corten-Dolan理论模型.该模型不但考虑了载荷间的相互作用效应,而且还考虑了载荷加载历史引起的强度退化的影响.同时提出了一种基于剩余强度衰减退化的零件疲劳寿命可靠性分析方法,即在假设剩余强度分布服从对数正态分布下,用零件的剩余疲劳损伤强度计算疲劳可靠度和预测零件疲劳可靠性寿命.通过基于修正Corten-Dolan模型的疲劳寿命预测和算例对比分析,该模型完善了传统Corten-Dolan理论模型的适用范围,提高了预测精度.以恒幅载荷作用下的疲劳可靠性描述为例,通过对比模型分析值和实验值,证实了基于剩余强度衰减退化的疲劳寿命可靠性分析模型的可行性,并可以推广至多级载荷作用下的疲劳可靠性寿命的预测.
Fatigue is a damage accumulation process in which the material property deteriorates continuously under cyclic loading.Through investigation of strength degradation in the material during the fatigue process,a nonlinear fatigue damage cumulative rule,a modified Corten-Dolan＇s theory,is proposed based on the definition of fatigue damage by introducing the concept of modulus degradation.This model improves the application of Corten-Dolan＇s theory,which considers not only the effects of load interaction but also the phenomenon of strength degradation in materials induced by the loading history.Moreover,the expressions for estimating fatigue reliability of structural elements under multiple loading levels are provided based on this model.These expressions can be used to predict the fatigue reliability and the life of structural elements under the assumption that the distribution of the residual strength can be approximated by the log-normal distribution.Two examples of two level stress loading tests are given for structural fatigue life estimation.The examples demonstrate that the fatigue life predicted by the proposed method is more accurate than those by traditional methods.The proposed method can be generalized to the cases of multilevel loading.
出处
《应用基础与工程科学学报》
EI
CSCD
2011年第2期323-334,共12页
Journal of Basic Science and Engineering
基金
国家高技术研究发展计划(863计划
2007AA04Z403)
四川省科技支撑计划(07GG012-002)
关键词
剩余强度
强度退化
非线性累积损伤准则
可靠性
寿命预测
residual strength
strength degradation
nonlinear fatigue damage cumulative rule
reliability
life prediction
