一种工业氧化铝的疲劳特性

Dynamic Fatigue Strength of a Commercial Alumina Ceramics

利用光滑和缺口试件研究了一种工业氧化铝陶瓷的动疲劳特性，给出了一种预测疲劳强度的简便方法。当加载速率σ．＜σ．ｃ时（σ．≈２０ＭＰａ），试件的动疲劳强度σＤＦ随σ．增大而升高，当σ．＞σ．ｃ，趋势出现逆转。对于应力集中系数Ｋｔ不同的试件，σ．ＤＦ—σ．关系曲线相互平行，并可用参量ＫｔσＤＦ归一化。统计分析显示，疲劳强度有可能遵从正态分布或对数正态分布。采用本文定义的等效应力，可获得光滑及缺口试件的统一ＳＰＴ（Ｓｔｒｅｎｇｔｈ－Ｐｒｏｂｏｂｉｌｉｔｙ－Ｔｉｍｅ）图。

The dynamic fatigue behavior of a commerical alumina ceramics is investigated with both unnotched and noteched specimens and a simple method is presented to predict the fatigue strength of material. The test results show that, the dynamic fatigue strength σ DF  rises with the loading rate as the loading rate is less that a critical value(20MPas -1 ) but the trend is reversed as the loading rate is higher than the critical value. The relation curves of the dynamic fatigue strength and the loading rate are parallel to each other and can be normalized by using the parameter K t σ DF . The statistical analysis indicates the fatigue strength of material may follow normal or log-normal distributions. The general SPT diagram can be obtained for both unnotched and notched specimens by means of the equivalent stress defined by the present study.