SPH耦合有限元方法的水射流弹塑性碰撞模拟

Elastic/plastic impact simulation of water jet using smoothed particle hydrodynamics and finite element method

针对有限元分析(FEA)处理流固耦合及超大变形问题时所存在的困难,提出了光滑粒子流体动力学(SPH)耦合有限元的方法来模拟水射流与刚性表面和塑性表面的碰撞过程.在SPH计算中,采用计算几何中的Voronoi图给每个SPH粒子赋予质量,并采用可变光滑长度考虑大变形中粒子相互间距的变化.分析了水射流与刚性表面的弹性碰撞,给出了射流变形与压力传播过程.对于水射流与塑性表面的碰撞,将SPH方法与有限元方法通过接触算法加以耦合,其中水射流以SPH粒子建模,而目标体以有限元方法建模.通过该耦合模型研究了在不同射流速度下切割深度与成坑孔径的变化,为理解切割机理和优化工作参数提供了参考.

To overcome the difficulty of fluid-solid interaction and extra large deformation problem of finite element analysis （FEA）, this work presented a coupled smoothed particle hydrodynamics （SPH） and finite element method to simulate the process of water jet impacting with the rigid and plastic target material. In the SPH computation, the Voronoi diagram in computational geometry was adopted to assign the initial particle mass and the variable smoothed length was used to consider the large distance change among the particles induced by the large deformation. According to the elastic impact computational result, the process of water jet colliding with the rigid target and then becoming into the state of flow was analyzed, also the deformation process of the water jet with the pressure propagation was given. And in the plastic impact computation, the SPH was combined with FEA by contact algorithm, where the water jet was molded by SPH particles and the target material was molded by finite elements. The relations of cut depth and crater size with different water jet velocity were studied, which was helpful to understand the water jet cutting mechanism and optimize the operating parameters.