疲劳寿命估算的能量法及其实验研究  

THE ENERGY METHOD FOR FATIGUE LIFE PREDICTION AND EXPERIMENT RESEARCH

作　　者：熊峻江[1] 王三平[2] 高镇同[1] 

机构地区：[1]北京航空航天大学固体力学研究所,北京100083 [2]中国直升机设计研究所,景德镇333001

出　　处：《力学学报》2000年第4期420-427,共8页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金!19672051;19802001

摘　　要：根据疲劳损伤滞后能等效原理，导出了缺口件与光滑件的当量应力关系，通过Neuber公式和炮和应力应变关系，可确定当量应力取值；采用定量方程随机化方法，建立了γ-p-ε-N曲线（置信度-可靠度-应变-寿命曲线）公式及其实验测试方法；根据疲劳累积损伤理论和γ-p-ε-N曲线公式，得到了随机载荷谱作用下构件疲劳寿命估算公式；最后，实验验证了复杂实测载荷谱作用下，LY12CZ铝合金含孔试样的疲劳寿命估算结果，并发现：估算与实验二者结果吻合较好．On the basis of the hysteresis energy conservation principle in fatigue damage process,the equivalent stress of the notch specimen are derived in this paper, taking account of the influence of initial crack length, cyclic behavior of materials, geometry of components and loading.With Neuber equation and the steady stress-strain curve,this equivalent stress may be calculated. By the randomization method of deterministic equation, the γ-p-Δε-N curves (confidence level-probability of survivaJ-strain-fatigue life curves), γ-p-Δεp-N curve and their experimental determination method have been established, in which the scatter of materials and the number of specimens are taken into account. By means of the Miner accumulation damage rule and γ-p-ε-N curves,the formulas to predict the safe life of components subjected to random load spectrum are presented and the predicted results accord with the fact that fatigue life is scatter in practice.Therefore, the energy approach to predict fatigue life of components has been obtained. At last,the fatigue test of the notched specimens of LY12CZ under the actual load spectrum is carried to validate the predicted results. From the test data, we have that the mean of experimental life is 1594.75 blocks, the median value of life is 1575.86 blocks on condition that logarithm of fatigue life follows Gauss distribution, aJnd the safe life with 99.9% probability of survival, 95% confidence level is 926.4 blocks. Using this energy method, the predicted median value of fatigue life is 1469.3blocks, and the predicted safe life with 99.9% probability of survitul, 95% confidence level is 879.6 blocks. From the calculated and experimental results above, it is found that the predicted result is smaller than the experimental data, but their deviation is very small. So it is confirmed that the results estimated are safe and agree with the experimental data.

关 键 词：滞后能 寿命估算 当量应力 疲劳 能量法 

分 类 号：O346.2[理学—固体力学]