Zr-4合金薄片材料的应变疲劳与寿命估算

Strain Fatigue and Life Estimate of Zr-4 Alloy Slice

完成了Zr 4合金漏斗形薄片小试样的横向等幅应变疲劳试验;根据试验分析和弹塑性有限元分析,提出了弹、塑性形状因子和等效泊松比的概念,发展了漏斗形薄片小试样横向应变向轴向应变换算的局部应变等效方法,并推荐了两种简化等效方法;由应变等效方法和疲劳试验结果,得到了Zr 4合金的M C(Man son Coffin)寿命估算模型.研究表明,对于漏斗形薄片小试样,按国标推荐的应变换算公式得到的M C模型对Zr 4合金的应变疲劳寿命预测过于安全,而由推荐的两种简化方法得到的M C模型对寿命估算有1～2倍的合理安全余量.

A series of strain fatigue tests on small slice specimens with 1-2 mm thickness of Zr-4 alloy were conducted. According to experimental analysis and EPFEA (Elastic and Plastic Finite Element Analysis), concepts of elastic-plastic shape factors and equivalent Poisson's ratio were presented. An equivalent strain method resulted from EPFEA was developed to transform transverse strain of bugle-specimen to uniaxial strain, and two simplified equivalent strain equations were recommended. By the new equivalent strain equations, M-C (Manson-Coffin) fatigue models of Zr-4 alloy were obtained based on the strain fatigue test results of Zr-4 alloy. The results show that for small slice specimen, the life prediction resulted from the traditional method has quite large safe factor. However, the life prediction resulted from the present two simplified equivalent strain methods has reasonable safe factor, ranging from 1 to 2 times.