摘要
拓展常规方法到三参数和Ｌａｎｇｅｒ模型，提出了估计三参数、Ｌａｎｇｅｒ和 Ｂａｓｑｕｉｎ三种常用应力一寿命模型 Ｐ─Ｓ─Ｎ曲线及置信限的一种统一常规方法。方法将曲线表示为对数疲劳寿命均值和均方差线的广义形式，至多６个材料常数，并方便地采用线性回归技术求解。４５碳钢缺口试样（ｋｔ＝２）对称循环加载模式成组法疲劳试验结果分析说明了方法的有效性。三参数模型的拟合效果最好，Ｌａｎｇｅｒ模型稍差，Ｂａｓｑｕｉｎ模型较差。从拟合误差和安全性角度，Ｂａｓｑｕｉｎ模型不宜描述该套数据。此外，常规方法的估计结果可能受到试验数据局部统计特征参量的影响，要避免有必要遵循各加载水平试样数相同的原则，或发展改进的可以最大限度减小这种影响的方法。
A unified conventional method for estimating P-S-N curves and their confidence bounds of the the commonly used fatigue stress-life relations, namely three three, parameter and Basquin, is presented by extrapolating conventional method to the three parameter and Langer relations. In the method, the curves are described by a general form of mean and standard deviation-curves of the logarithm of fatigue life, in which sir material constants are at most contained. Material constants are conveniently evaluated by a linear regression technique. Availability of present method has ben indicated by an analysis of the test data of 45 carbon steel-notched speci mens (kt = 2) subjected to fully reversed axial loads. The fit is best for three-parameter relation, slightly inferior for the Langer one and poor for the Basquin. Considering the fitted error and the safety in practice, the Basquin one is not an appropriate relation for the dsta. In addition, present work verifies that the conventional method-based predictions might be affected by the local statistical characteristics of test data. To avoid the affects, the number of specimens at each test load should be kept as same as possible without less than certain value to assure enough accuracy. An improved method, which could reduce the affects to a minimum, should be worthily explored.
出处
《机械强度》
CAS
CSCD
北大核心
2000年第3期217-221,共5页
Journal of Mechanical Strength
基金
中国博士后科学基金!(99-2000)
国防科委95预研!(27.1.1)
四川省应用基础研究和铁道部科技发展项目!(97.1
