Unreasonable contact force in cutting simulation

MinerMiner Member
edited November 9 in Explicit Dynamics

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?

(2) Rock block consists of SPH part and FEM part, why there is a gap bewteen SPH and FEM in post-processing? It seems that some particles disappeared. Their interaction is defined by *CONTACT_TIED_NODES_TO_SURFACE.


  • FernandoTorresFernandoTorres Madrid, SpainMember

    Hi @Miner , I can't answer it but may I ask you, what's the reason to go with LS-DYNA instead of Autodyn explicit? Thanks.

  • Acctually, I have no experience of Autodyna explicit. I followed sime literatures, LS-DYNA is widely used in cutting simulation.

  • cxquancxquan Berkeley, CAForum Coordinator

    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.

    About the gap between SPH & FEM, will it disappear if you increase SPH particle density by reducing the particle size?

  • MinerMiner Member
    edited November 10

    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.

    Yeah, the gap only appears when particles size is small.

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