压裂泵阀箱自增强技术仿真研究

Fatigue Life Analysis for Fluid Cylinder Based on Autofrettage Technology

基于弹塑性自增强理论,对压裂泵阀箱进行了弹塑性有限元非线性研究,探讨了自增强技术和机械加工精度对阀箱疲劳寿命的影响。分析了不同自增强压力下的阀箱应力,确定了阀箱内腔相贯线处最佳自增强压力为420.6 MPa。对自增强前后阀箱的疲劳寿命进行预测结果表明:阀箱疲劳薄弱区位于内腔相贯线处,自增强后疲劳薄弱区向壁间转移,偏离了疲劳危险区域,阀箱内壁表面材料得到有效保护。自增强技术使阀箱应力峰值降低了30.61%,最低疲劳寿命提高了6.97倍。自增强技术与提高阀箱内腔表面加工精度的方法相比,前者对延长阀箱疲劳寿命效果更佳。

Abstract： Based on autofrettage technology of elastic plastic theory, the stress distribution of fracturing fluid cylinder was obtained by the elastic plastic nonlinear finite element analysis for a domestic fracturing pump, which was em ployed to research how to improve fatigue life of the fluid cylinder by using autofrettage technology or improving ma chining accuracy Through comparing the maximum stress under different autofrettage pressure levels, the best auto frettage pressure level of fluid cylinder＇s intracavity intersection was determined as 420.6 MPa. According to SN de sign criteria, a prediction life of fluid cylinder could be conducted by using Msc. Fatigue code. Results indicated that the fatigue regions of autofrettage fluid cylinder had been transferred to inner places and had been deviated from the fatigue danger zone, namely intracavity intersection. The intracavity intersection was effectively protected, and the stress peaks of the fluid cylinder reduced by 30.61% and its minimum fatigue life increased by 6.97 times after auto frettage. Compared with improving machining accuracy, the autofrettage technology can increase the fluid cylinders life much more effectively.