标准差S在材料疲劳寿命分析中的作用

目前,在评价材料的疲劳强度时,往往只注重比较材料的中值疲劳寿命,而忽略了对数据分散性的比较.事实上,数据分散性,尤其是标准差S在评价材料疲劳性能时非常重要.本文通过对比几组相同试验条件下中国和美国生产的同一铝合金材料的疲劳数据发现:两个产地材料的中值疲劳寿命基本接近,但美国产材料疲劳数据的标准差S小.其对应99.99%存活率的疲劳寿命也明显高于国产材料,这表明标准差大小对高存活率下的疲劳寿命影响很大.因此,应对标准差S给予高度重视.

Effect of Standard Deviation-S in Fatigue Test Data Analysis

Median fatigue life is usually used to estimate the fatigue properties of materials while the dispersibility of the data is always ignored.In fact the dispersibility of the data,especially the standard deviation is very important in estimating materials.In this paper two kinds of aluminium alloys produced by China and America were used to carry out fatigue tests under same loading condition.It was found that the median fatigue lives of the aluminium alloys are very close.The fatigue data of aluminium alloys produced in America have less standard deviation and their fatigue lives with 99.99% livability are longer than those produced in China. It shows that the standard deviation has great effect on the fatigue lives with big livability. So it should be paid more attention to the standard deviation.