基于Ls-Dyna的高能射流式冲击器活塞杆回程应力分析

针对在钻探实践中高能射流式冲击器的活塞杆频繁出现尾部塑性变形严重影响冲击器工作性能和整体寿命的现象，拟对活塞杆进行优化改进。利用非线性动力学仿真软件Ls-Dyna对活塞杆的回程撞击缸体进行数值模拟和优化分析，并进行了室内试验，结果表明：冲击末速度为4 m/s，活塞杆回程撞击缸体强制停止运动瞬间，尾部产生的应力集中值为3 339.28 MPa，导致其破坏；优化改进后，活塞杆上下端直径比为17/16、尾部圆弧直径为60 mm，活塞杆体内的应力集中值为1 419.66 MPa，较改进前活塞杆的应力集中值减小58%。试验验证表明，优化后的活塞能大幅提高使用寿命和耐久性。

Stress Analysis of the Piston Rod Return in High-Energy Liquid-Jet Hammer Based on Ls-Dyna

The plastic deformation of piston rod of the liquid-jet hammer with high impacting energy is a key issue, which seriously affects the performance and working life. Numerical simulation is conducted to analyze the piston return impacting process and optimize parameters by nonlinear dynamics simulation software Ls-Dyna. Laboratory test is also carried out for the validation of the analysis. The results show that a very high concentrated stress of 3 339.2 MPa appears at the end of the piston rod when the piston rod impacts the cylinder block with the velocity of 4 m/s. The high transient stress is likely to lead to destruction of the piston rod. By optimizing the diameter ratio of the top surface to the bottom surface and the tail arc diameter of the piston rod to the value of 17/16 and 60 mm, respectively, the maximum transient stress is reduced to 1 419.66 MPa with a 58% decrease, which can largely improve the piston rod performance and working life.