比例超载对铝合金圆孔薄板试件低周拉-拉疲劳寿命的影响

对铝合金圆孔薄板试件进行了超载和常辐的对比实验,取六种超载比,对每一超载比各进行了不同超载周次的实验,从这些实验结果看出,对每一超载比,超载试件的疲劳寿命和常辐疲劳试件的寿命比值先是随超载周数的增加而较快的增加,之后在一个相当大的超载周数范围内,超载寿命比的变化不大。当超载周数超过一定值时,超载寿命比随超载周数的增加而略有减少。本文的实验中,在超载60％的情况下,超载周数从20周到90周的范围内,超载试件的平均寿命比常辐疲劳试件的寿命约高3.5倍。

THE EFFECT OF PROPORTIONAL OVERLOAD ON THE LOW CYCLE TENSION-TENSION FATIGUE LIFE OF ALUMINIUM ALLOY PLATE WITH CIRCULAR HOLE

It is presented in this paper the experimental study of low-cycle fatigue with constant amplitude and overload for aluminium alloy plate with circular hole.During the research six different over load ratios have been selected and different over load cycles have been carried out.It is concluded that for each given over load ratio, the over load fatigue life ratio(ratio of fatigue life for over loaded specimen over the fatigue life for constant amplitude specimen)increases with the increase of over load cycle at the beginning and then kept constant for a wide range of over load cycles. After the overload cycles exceed a certain number of cycles ,-the overload fatigue life ratio would be decreased with the increase of overload cycles.It is also presented in the paper that the average fatigue life for overload specimen in the case of 60% overload and in the range of overload cycles from 20 cycles to 90 cycles is about 3.5 times higher than the fatigue life for specimen tested under constant amplitude fatigue.