升降法试验数据闭合与否对统计估计材料疲劳强度的影响

Influence of Staircase Fatigue Test Data Closed or Not on Statistical Estimation of Material Fatigue Strength

列举了2种未闭合的升降图并对升降法疲劳试验过程中可能出现的试验结果进行假设,分析了用升降法统计疲劳强度时试验数据是否闭合对疲劳强度结果的影响。结果表明:当试验数据未闭合的升降图中最后一级应力低于第一个有效应力时,后续增补假设升降图后统计的疲劳强度都低于原未闭合疲劳试验升降图统计的疲劳强度;当试验数据未闭合的升降图最后一级应力高于第一个有效应力时,后续增补假设升降图后统计的疲劳强度也都高于原未闭合疲劳试验升降图统计的疲劳强度。即使试验数据未闭合,按照失效事件及未失效事件统计估计的疲劳强度也可能相等。

Two types of unclosed staircase chart were cited,and reasonable assumptions were made on the test results that may appear during the staircase fatigue test.The effect of test data closed or not on the fatigue strength was analyzed when the fatigue strength was statistically estimated by the staircase method.The results show that when the lastlevel stress in the staircase chart of unclosed test data was lower than the first effective stress,the statistically estimated fatigue strength after subsequent supplementary of hypothetical staircase chart was also lower than the statistically estimated fatigue strength from the original unclosed fatigue test staircase chart.When the last-level stress of the staircase chart of unclosed test data was higher than the first effective stress,the statistically estimated fatigue strength after subsequent supplementary of hypothetical staircase chart was also higher than the statistically estimated fatigue strength from the original unclosed fatigue test staircase chart.Even if test data was not closed,the fatigue strength statistically estimated from failure events and non-failure events may be equal.