LS Dyna

LS Dyna

Unreasonable contact force in cutting simulation

    • Miner
      Subscriber

      Dear all,

      (1) I am modeling a disc cutter (FEM) cutting rock block (SPH), and the interaction between rock and cutter is defined with *CONTACT_AUTOMATIC_NODES_TO_SURFACE, fs=fd=0.3. The expected rolling force (contact force in the Y direction) should be always positive or negative (depends on it from slave or master). However, my results show that the Y force fluctuates around zero. Could you give me some suggestions?

    • Fernando Torres
      Subscriber
      I can't answer it but may I ask you, what's the reason to go with LS-DYNA instead of Autodyn explicit? Thanks.n
    • Miner
      Subscriber
      Acctually, I have no experience of Autodyna explicit. I followed sime literatures, LS-DYNA is widely used in cutting simulation.n
    • Chris Quan
      Ansys Employee
      The roller has two motions: translation and rotation. These motions may pose different direction of the force. Suggest you running another two simulations: one with translation only and the other with rotation only. These two simulations will justify the force direction for each motion and may explain what you observed. nAbout the gap between SPH & FEM, will it disappear if you increase SPH particle density by reducing the particle size?.
    • Miner
      Subscriber
      Thanks for the reply. I tried these two conditions and It indeed that these two motions pose different direction of the force. If I decrease slightly the rotation speed, this issue will be resolved. In experiment, the rotation of cutter is driven by the friction from rock, which is different with numerical model.nYeah, the gap only appears when particles size is small.
    • Miner
      Subscriber
      In the previous model, contact between SPH and FEM is defined by part ID. The gap is addressed by changing PART to Node set (defined by the node at the lateral and bottom of the SPH part) and segment set (Surface of the FEM groove).n
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