CONTACT_AUTO_MOVE to eliminate initial contact clearances

In many situations, initial clearances between two contact surfaces can cause convergence issues in IMPLICIT analyses while wasting simulation time in EXPLICIT analyses. To remove the initial contact clearance, LS-DYNA offers a capability using *CONTACT_AUTO_MOVE that helps to improve convergence in IMPLICIT analyses since contact is detected immediately.

Contact AUTO_MOVE associates itself with another contact (two-way and one-way ONLY) and
attempts to move the MASTER nodes during the initialization(cycle 0) such that the minimum
clearance is 0.5*0.5*(slave_thickness+master_thickness). This causes LS-DYNA to see an
initial penetration of 0.5*(slave_thickness+master_thickness) at cycle 1 causing both slave
and master segments to receive forces from the contact algorithm.


  • To overcome the movement of both surfaces, you can turn on IGNORE=1 either in *CONTROL_CONTACT
    or at the *CONTACT level.
  • AUTO_MOVE only works with one-way and two-way contact types

Here is a link to a simple example.

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