模糊数学在疲劳寿命估算中的应用

结构部件在承受交变载荷时,疲劳破坏为常见的破坏形式。目前疲劳寿命预测的方法有多种,在工程实际应用中,多选用Miner法进行寿命预测。然而当载荷稍低于疲劳极限时,对构件是否产生损伤便产生了一定的模糊性,把模糊数学理论引入线性损伤累积理论即Miner公式中,并由一维模糊Miner公式推广到二维模糊Miner公式中,以便更好地在工程中应用。同时对不同隶属函数的选取进行了比较,指出隶属函数对提高预测精度有着重要的影响。并将二维模糊Miner公式应用于××飞机结构寿命预测中,其所预测的结果比二维Miner公式所预测的结果的精度提高7%左右。

Fatigue Life Estimation for Using Fuzzy Mathematics

Structural components subjected to variable loading may usually tend to fatigue failure. With the accumulation of fatigue damages, some accidents will occur. Therefore, how to predict fatigue life of the structure component is a very important problem. Although many damage models have been put forward, the most widely used one is the linear damage model. The model is often referred to as Miner’s rule, whereas it is fuzzy when the stress that the structural components subjected to is slightly lower than the fatigue limit. The fuzzy factor are taken into account and the new approach is given. In order to apply Miner’s rule conveniently, the two-dimensional fuzzy Miner’s rule is investigated. At the same time, different membership functions are studied, which have important influence on the result of estimating fatigue life. The structural fatigue life of ×× airplane is estimated by adopting the two-dimensional fuzzy Miner’s rule. By comparing the result with that of two-dimensional Miner’s rule, the conclusion is drawn that the accuracy increased about 7%.