钛合金挠性轴裂纹延展规律与寿命预测  

Crack Propagation Law and Service Life Prediction of Titanium Alloy Flexible Shaft

作　　者：张洪霖 范楷模 王宇鹏 郭添鸣 米凯夫 张一帆 Zhang Honglin;Fan Kaimo;Wang Yupeng;Guo Tianming;Mi Kaifu;Zhang Yifan(Beijing Petroleum Machinery Co.,Ltd.)

机构地区：[1]北京石油机械有限公司

出　　处：《石油机械》2021年第9期40-47,共8页China Petroleum Machinery

基　　金：中国石油集团工程技术研究院有限公司科学研究与技术开发项目“重大工程关键技术装备研究与应用(二期)”(2018E-2108)。

摘　　要：为延长钛合金挠性轴使用寿命及计算服役时长,通过理论推导,论证了应用S-N曲线进行材料寿命预测的可行性;通过超高周疲劳试验,得到了疲劳应力S-N曲线。通过有限元方法计算出钛合金挠性轴在不同圆角下的应力集中系数,模拟了不同圆角值和弯角值下的应力分布状态,优化出圆角的最优解,并计算出最优解时钛合金挠性轴在不同弯角下的安全系数,以此确定弯角许用的极大值,推导出优选值下挠性轴使用的极短时长。通过断裂力学仿真分析,计算出不同裂纹深度下的应力极值变化规律与裂纹深度最值;根据Paris公式及有限元计算结果推导出挠性轴的极限循环周次及裂纹的延展速率,从而探究了钛合金挠性轴的裂纹萌生规律。现场试验中挠性轴的循环周期约为2.268×10^(6)周次,大于裂纹萌生时长,但小于2.848×10^(6)周次的循环极值,判定挠性轴应有裂纹萌生。现场试验与金相组织检查结果证实了裂纹萌生及扩展规律计算的正确性。In order to prolong the service life and calculate the service time of titanium alloy flexible shaft,this paper demonstrated the feasibility of using S-N curve to predict the service life of titanium alloy material,and used ultra-high cycle fatigue test to obtain the S-N curve of fatigue stress.By means of finite element method,this article figured out the stress concentration factor of titanium alloy flexible shaft under different round angles,simulated the stress distribution state under different round angles and bend angles,optimized the optimal solution of round angle,and figured out the safety factor of titanium alloy flexible shaft under different bend angles at optimal solution;based on which,further determined the maximum allowable bend angle,and derived the limit duration for service of flexible shaft under optimal value.Moreover,by means of simulation analysis of fracture mechanics,this paper figured out the variation law of stress extremum under different crack depths and the maximum value of crack depth;based on the Paris equation and the finite element calculation results,derived the limit cycle times and the crack propagation rate of the flexible shaft,and thus explored the crack initiation law of the titanium alloy flexible shaft.In the field test,the cycle times of the flexible shaft are about 2.268×10^(6) cycles,which are greater than those of the crack initiation time,but less than the cycle extremum of 2.848×10^(6) cycles,so it is judged that crack initiation might occur in the flexible shaft.The field test and metallographic structure inspection results confirm the correctness of the calculation of crack initiation and propagation law.

关 键 词：钛合金 挠性轴 应力分布 寿命预测 裂纹深度 现场试验 

分 类 号：TE921[石油与天然气工程—石油机械设备]