Boundary/Constraint to fix node set (all DOF = 0)

autumnautumn Member
edited December 2020 in Explicit Dynamics

Hi,

(I am working within LS-prepost v4.7)

I am attempting to fix a set of nodes on the bottom side of a cube such that all DOFs are equal to zero. I have tried CONSTRAINED_NODE_SET and a couple other keywords under BOUNDARY and CONSTRAINED, but run into the issue of not being able to select all DOFs = 0. Instead, I still need to define at least one translational or rotational free DOF.

Since I am very new to LS-Dyna in general, I assume this issue is only due to my inexperience and it would be great if someone could point me in the right direction in order to completely fix a given node set (or segment set or face). I have tried searching this question elsewhere and looked through some manuals, but have yet to find an answer.

I have attached a screenshot of the geometry of my model below - the blue plate will be impacting the red cube at a given initial velocity and I am trying to properly constrain the sides of the cube with certain of DOFs equal to zero (e.g. the bottom side having all DOFs = 0).

Thanks in advance for any help.


Best Answer

  • igandikoigandiko Member
    Accepted Answer

    Hi,

    You can use LSPP to constraint the nodes (individually or using a set id), LSPP -> Model and part -> Create entity -> Boundary SPC -> Cre -> Set -> select nodes (in pick nodes dialog, using element option with 'Prop' turned on allows you to grab nodes of entire surface with a single click).

    (or) You can also create the set first (Create entity -> SET_NODE) and then go to Keyword manager -> All -> *BOUNDARY_SPC_SET keyword and select the set id and DOF. Note that DOFX =1 constraints x translational DOF (0 = no constraint). Please refer *BOUNDARY card in LS-DYNA user's manual for more information.

Answers

  • igandikoigandiko Member
    Accepted Answer

    Hi,

    You can use LSPP to constraint the nodes (individually or using a set id), LSPP -> Model and part -> Create entity -> Boundary SPC -> Cre -> Set -> select nodes (in pick nodes dialog, using element option with 'Prop' turned on allows you to grab nodes of entire surface with a single click).

    (or) You can also create the set first (Create entity -> SET_NODE) and then go to Keyword manager -> All -> *BOUNDARY_SPC_SET keyword and select the set id and DOF. Note that DOFX =1 constraints x translational DOF (0 = no constraint). Please refer *BOUNDARY card in LS-DYNA user's manual for more information.

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