摘要
基于不同应力水平下试样疲劳寿命对应的概率分位点的一致性,研究小样本疲劳试验数据信息提取原理与P-S-N曲线试验数据统计处理方法。通过聚集不同应力水平下的寿命试验数据、融合不同应力水平下的寿命分布信息,实现各级应力水平下寿命分散性信息的集成应用。借助失效迹线和等效寿命概念,以及等效寿命分布与真实寿命分布一致性判据,提出确定寿命标准差与循环应力水平之间关系的方法。在寿命中值(均值)-应力水平关系已知、寿命标准差-应力水平关系待定的情况下,基于等效寿命分布与真实寿命分布一致性的统计检验,应用摄动寻优技术确定疲劳寿命标准差-循环应力水平方程。这种方法相当于把不同应力水平下的疲劳寿命试验数据转换为任一指定应力下的等效寿命,从而得到等效大样本数据,拟合出较为精确的P-S-N曲线。试验表明,此方法能在较小样本量(20～30)的条件下,获得与传统成组法(40～60个样本)接近的P-S-N曲线,且容易应用。
In sense of probability percentiles, there exists a correspondence between specimen fatigues lives associated with different cyclic stress levels. Based on such a correspondence, the principle to fit P-S-N curve with small sample test data is investigated, which related with information fusion techniques, and the method to establish P-S-N equation. By polymerizing fatigue life test data under different cyclic stress levels and integrating the life distribution information, small sample experiment data can be efficiently applied to acquire the necessary information to estimate the parameters of the probability distributions of fatigue lives associated with any stress levels. According to the relationship between life distribution and cyclic stress level, fatigue life test data at different stress levels can be equivalently converted to an arbitrarily specified baseline stress level, and the distribution of the equivalent lives is identical with that of the test data at the baseline stress level if the relationship is correct. With the mean life - stress level relationship fitted by small sample test data, the correct relationship between life standard deviation and stress level can be found by statistical test oriented perturbation technique. Test results illustrate that the P-S-N curves fitted by this method with 20-30 specimens are very close to those obtained by fitted by conventional method with 40-60 specimens.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2013年第15期96-104,共9页
Journal of Mechanical Engineering
基金
国家自然科学基金(51175072)
高等学校博士学科点专项科研基金(20110042130003)资助项目
关键词
P-S-N曲线
小样本
样本集聚
信息融合
等效寿命
P-S-N curve Small size sample Sample congregation Information fusion Equivalent life
