基于LS-DYNA仿真的射流加工参数分析

目的通过LS-DYNA对磨料射流冲蚀切削进行仿真,研究相关工艺参数对切削参数的影响。方法采用磨料水射流对Al_2O_3陶瓷进行了单点冲蚀仿真和切削仿真研究,其中水和磨料粒子采用SPH方法建模,氧化铝陶瓷工件采用FEM方法建模,并通过SPH-FEM耦合算法,实现射流冲蚀切削过程的仿真。结果分析射流冲蚀过程仿真和切削过程仿真可知,射流加工前期,由于射流中磨粒碰撞与反弹,使壁面成不规则"V"型。初始阶段,切深随计算时间呈线性增加,同时壁面对磨粒产生制约作用,从而使加工处的孔深基本不再增加。由于磨粒在冲蚀处壁面底部的冲蚀作用,使凹坑底部宽度增加并迅速趋于稳定。同时切削仿真与冲蚀仿真也存在一定区别,主要由于切削过程设定了移动速度。结论将仿真结果与实验结果进行比较可知,切削深度随着泵压的增大而成线性增大,切深随磨料流量的增大而增大,随靶距和横移速度的增大而减小。其中切深与磨料流量、靶距、横移速度均为非线性关系,工件最大切深与计算时间不呈线性关系增长。

Analysis of Jet Flow Machining Parameters Based on LS-DYNA Simula-tion

The work aims to study effects of relevant technological parameters on cutting parameters by simulating abrasive jet flow erosion and cutting with LS-DYNA. Based on the single abrasive water jet single-point erosion simulation and cutting simulation, both water and abrasive particles were modeled in the method of SPH, alumina ceramic workpiece was modeled in the method of FEM, and jet erosion and cutting process was simulated through SPH-FEM coupling algorithm. According to simulation analysis of jet erosion process and cutting process, abrasive collision and rebound contributed to irregular "V" type wall in early stage of jet machining. At the initial phase, cutting depth increased linearly as time prolonged; the wall had a restrictive effect on the abrasives, therefore hole depth in machining position no longer increased. The abrasives erosion at the bottom of the wall enabled the pit bottom width to increase and tend to be stable rapidly. Meanwhile, there is certain difference between cutting simulation and erosion simulation as the cutting process has set movement speed. Comparison of simulation results with experimental results shows that cutting depth increases linearly as pump pressure increases, increases as the abrasive flow rate increases, and decreases as target distance and traverse speed increases. The cutting depth has nonlinear relationship with abrasive flow rate, target distance and traverse speed; maximum workpiece cutting depth does not grow linearly as and calculation time prolongs.