SPH模拟螺杆挤出的粒子穿透边界问题研究

Study of Particle Penetration through Boundaries in SPH Simulation for Screw Extrusion

采用光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)模拟双螺杆挤出时,常会出现粒子穿透边界的问题,这是由于螺杆挤出过程存在“挤压流”这一特殊流动现象而造成的。过去的“人工声速判据”不适用于解决“挤压流”这类问题。为了修正“人工声速判据”的缺陷,针对挤压过程进行推算,提出了一种理论计算“特征速度”的方法。为了验证该方法的有效性,对SPH的模拟结果与传统商业软件POLYFLOW的模拟结果进行了比较。结果显示,新计算方案的运用可以有效避免粒子穿透边界的问题。这种计算方案可为其他存在“挤压流”现象的复杂加工模拟解决粒子穿透边界问题提供参考。

When using smoothed particle hydrodynamics(SPH)to simulate twin-screw extrusion,the problem of particle penetration through boundaries often occurs.This is due to the special flow phenomenon of"extrusion flow"in the screw extrusion process,and the previous"artificial sound velocity criterion"was not applicable to solving special cases such as"extrusion flow".In order to correct the shortcomings of the"artificial sound velocity criterion",a theoretical method for calculating the"characteristic velocity"was proposed for the extrusion process.To verify the effectiveness of the method,the simulation results of SPH were compared with those of the traditional commercial software POLYLOW.The results show that the application of the new calculation scheme could effectively avoid the problem of particle penetration through boundaries,and this calculation scheme also provided a reference for solving the problem of particle penetration through boundaries in other complex machining simulations with extrusion flow.