Learning Forum

[paul.gouezec]

Hello everyone,

I'm a M.Sc student in Civil Engineering and I'm currently working with FEM on LS-DYNA. As part of my research, I need to connect a nodal mass to each node of an elastic solid element, using rigid links. (I've attached a picture for clarity). I've tried the card NODAL_RIGID_BODY but it won't work, unless I connect each node of the solid to the nodal mass, which I don't want to (I just want to connect the nodal mass to the side facing the nodal mass (the hatched side on the picture)). I've been looking into the User Manual and I wanted to try the following cards to create these rigid links:

- CONSTRAINED_BEAM_IN_SOLID

- CONSTRAINED_JOINT_TRANSLATIONAL

- CONSTRAINED_JOINT_LOCKING

- CONSTRAINED_JOINT_CONSTANT_VELOCITY

- CONSTRAINED_LINEAR_GLOBAL

- CONSTRAINED_MULTIPLE_GLOBAL

(- CONSTRAINED_NODAL_RIGID_BODY)

- CONSTRAINED_NODE_INTERPOLATION

- CONSTRAINED_NODE_SET

- CONSTRAINED_SOLID_IN_SOLID

 

Rather than trying each one of these parameters, I was wondering if someone could help me with rigid links.

 

Thanks!

[Dennis Chen]

 

here’s an example of what you may be able to do.   you can also try constraint_extra_node_set, part_inertia, constrained_nodal_body_insertia, etc but below should work as an example

node 75670 is created and then added to a node set containing your red surface (all nodes).   constrained_nodal_rigid_body is created, including node set which includes 75670.   element_inertia is added to node 75670, giving it mass.

this way, node set 10, which contains all your red nodes and the extra node 75670, has the added mass 0.1.    Hope this helps. 

*NODE

   75670     -3.49999964    197.02796621   -436.77937166                        

*SET_NODE_LIST

        10

     75670    xx, xx, xx, xx

*CONSTRAINED_NODAL_RIGID_BODY

$      pid       cid      nsid     pnode      iprt    drflag    rrflag   unused1

        45         0        10         0         0         0         7          

*ELEMENT_INERTIA

$     ID     nid    csid                                                 unused1

  114045   75670       0                                                        

$      ixx       ixy       ixz       iyy       iyz       izz      mass   unused2

         0         0         0         0         0         0       0.1    

 

[paul.gouezec]

I'm going to try this, thanks!