确定材料概率疲劳曲线的损伤力学方法

飞机结构对可靠度要求很高,因此要获取材料的概率疲劳曲线.概率疲劳曲线试验周期长,费用高.对此,首次通过损伤力学方法,根据获取材料中值疲劳曲线所需数据确定了材料的概率疲劳曲线.结果表明,当存活概率提高时,疲劳强度将明显降低,疲劳寿命将明显缩短.本结论是从金属材料的标准试件的疲劳试验推出的,因而该方法首先适用于金属材料,同时该方法也可推广用于许多新型的复合材料.另外,试验子样愈大,置信度愈高.该方法的价值在于可以采用中值疲劳试验代替概率疲劳试验,显著地节约疲劳机时与试验成本.

Method of damage mechanics to determine the p-S-N curve of material

High reliability is required in the structures of aero planes, it is necessary to determine the probability fatigue curves of materials. It is well known that it is very expensive and takes numerous time to obtain probability fatigue curves by fatigue tests. Due to this situation, by means of the method of damage mechanics, for the first time a p-S-N curve can be determined according to its median S-N curve and the corresponding fatigue data. The result shows that the fatigue strength and the fatigue life decrease greatly with the increase of the survival probability. This conclusion was obtained from the fatigue tests of metals, so this method can be used under this condition. However, it can be also extended to some new kinds of composite materials. In addition, it should be indicated that the confidence will be higher with a larger sample. The significance of this method is that median fatigue tests can be used to replace probabilistic fatigue tests in order to draw p-S-N curves. Thus the time and the cost of fatigue tests will be reduced greatly.