Learning Forum

[Jacob Ellis]

I have two blocks touching each other. I am trying to keep them bonded using *CONTACT_AUTOMATIC_SINGLE_SURFACE_TIED while displacing one side of block A and block B has one side fixed. 

To me, this seems like a simple problem that should work for this contact. I can accomplish this with other contacts. From the definition of CLOSE, if set to zero it uses a default value that should capture the nodes of the other surface. My contact definition using the keyword manager in 2023R2 is below.

[Chris Quan]

The Slave Segment Set is defined in the Keyword. However, the Master Segment Set is not defined. 

So if the Block A is the moving part, the face on the Block A can be defined as the geometry in the Master Segment Set, while the face on the Block B can be defined as the geometry in the Slave Segment Set.

 

[Jacob Ellis]

Hi Chris, thanks for your comment. This is a single surface contact type. Master surface is not needed. For a sanity check I tried it anyways and it gives an error telling me so. 

[Chris Quan]

Hi Jacob, sorry, you are right. Single surface contact doesn't need the Master Segment Set.  

Can you write the input file from WB LS-DYNA GUI and then check the Keyword *CONTACT_AUTOMATIC_SINGLE_SURFACE_TIED to see if it has been written correctly?

[Jacob Ellis]

Chris, I wrote out the input deck and reviewed it in LS-PrePost. I can't see a single thing wrong with it. 

 

One thing to note is that with MPP the solver runs but the blocks separate. With SMP it fails with this error.

Interface 280 references to CID 280 above. It is the only contact definition in the problem. Segment Set 4 is the only segment set defined. 

[Jacob Ellis]

Below is a small example made from scratch in LS-PrePost

====

$# LS-DYNA Keyword file created by LS-PrePost(R) V4.10.3-21Apr2023
$# Created on Oct-27-2023 (20:26:28)
*KEYWORD
*TITLE
$#                                                                         title
LS-DYNA keyword deck by LS-PrePost
*CONTROL_TERMINATION
$#  endtim    endcyc     dtmin    endeng    endmas     nosol
      0.01         0       0.0       0.01.000000E8         0
*BOUNDARY_PRESCRIBED_MOTION_SET
$#    nsid       dof       vad      lcid        sf       vid     death     birth
         2         1         2         1      -1.0         01.00000E28       0.0
*BOUNDARY_SPC_SET
$#    nsid       cid      dofx      dofy      dofz     dofrx     dofry     dofrz
         1         0         1         1         1         1         1         1
*SET_NODE_LIST_TITLE
fixed
$#     sid       da1       da2       da3       da4    solver       its         -
         1       0.0       0.0       0.0       0.0MECH      1                   
$#    nid1      nid2      nid3      nid4      nid5      nid6      nid7      nid8
         3         6        15        12         9        18        24        21
        27         0         0         0         0         0         0         0
*CONTACT_AUTOMATIC_SINGLE_SURFACE_TIED
$#     cid                                                                 title
$#   surfa     surfb  surfatyp  surfbtyp   saboxid   sbboxid      sapr      sbpr
         1         0         0         0         0         0         0         0
$#      fs        fd        dc        vc       vdc    penchk        bt        dt
       0.0       0.0       0.0       0.0       0.0         0       0.01.00000E20
$#    sfsa      sfsb      sast      sbst     sfsat     sfsbt       fsf       vsf
       1.0       1.0       0.0       0.0       1.0       1.0       1.0       1.0
$#   close
       0.0
*SET_SEGMENT
$#     sid       da1       da2       da3       da4    solver       its         -
         1       0.0       0.0       0.0       0.0MECH               0          
$#      n1        n2        n3        n4        a1        a2        a3        a4
        30        33        42        39       0.0       0.0       0.0       0.0
        33        36        45        42       0.0       0.0       0.0       0.0
        39        42        51        48       0.0       0.0       0.0       0.0
        42        45        54        51       0.0       0.0       0.0       0.0
*MAT_ELASTIC
$#     mid        ro         e        pr        da        db  not used
         17.83000E-9  207000.0       0.3       0.0       0.0       0.0
*PART
$#                                                                         title
boxsolid
$#     pid     secid       mid     eosid      hgid      grav    adpopt      tmid
         1         1         1         0         0         0         0         0
*SECTION_SOLID
$#   secid    elform       aet    unused    unused    unused    cohoff   gaskeit
         1         1         0                                     0.0       0.0
*PART
$#                                                                         title
boxsolid
$#     pid     secid       mid     eosid      hgid      grav    adpopt      tmid
         2         1         1         0         0         0         0         0
*DEFINE_CURVE
$#    lcid      sidr       sfa       sfo      offa      offo    dattyp     lcint
         1         0       1.0       1.0       0.0       0.0         0         0
$#                a1                  o1
                 0.0                 0.0
                0.01                 1.0
*ELEMENT_SOLID
$#   eid     pid      n1      n2      n3      n4      n5      n6      n7      n8
       1       1       1       2       5       4      10      11      14      13
       2       1       2       3       6       5      11      12      15      14
       3       1       4       5       8       7      13      14      17      16
       4       1       5       6       9       8      14      15      18      17
       5       1      10      11      14      13      19      20      23      22
       6       1      11      12      15      14      20      21      24      23
       7       1      13      14      17      16      22      23      26      25
       8       1      14      15      18      17      23      24      27      26
       9       2      28      29      32      31      37      38      41      40
      10       2      29      30      33      32      38      39      42      41
      11       2      31      32      35      34      40      41      44      43
      12       2      32      33      36      35      41      42      45      44
      13       2      37      38      41      40      46      47      50      49
      14       2      38      39      42      41      47      48      51      50
      15       2      40      41      44      43      49      50      53      52
      16       2      41      42      45      44      50      51      54      53
*NODE
$#   nid               x               y               z      tc      rc
       1           100.0             0.0             0.0       0       0
       2           150.0             0.0             0.0       0       0
       3           200.0             0.0             0.0       0       0
       4           100.0            50.0             0.0       0       0
       5           150.0            50.0             0.0       0       0
       6           200.0            50.0             0.0       0       0
       7           100.0           100.0             0.0       0       0
       8           150.0           100.0             0.0       0       0
       9           200.0           100.0             0.0       0       0
      10           100.0             0.0            50.0       0       0
      11           150.0             0.0            50.0       0       0
      12           200.0             0.0            50.0       0       0
      13           100.0            50.0            50.0       0       0
      14           150.0            50.0            50.0       0       0
      15           200.0            50.0            50.0       0       0
      16           100.0           100.0            50.0       0       0
      17           150.0           100.0            50.0       0       0
      18           200.0           100.0            50.0       0       0
      19           100.0             0.0           100.0       0       0
      20           150.0             0.0           100.0       0       0
      21           200.0             0.0           100.0       0       0
      22           100.0            50.0           100.0       0       0
      23           150.0            50.0           100.0       0       0
      24           200.0            50.0           100.0       0       0
      25           100.0           100.0           100.0       0       0
      26           150.0           100.0           100.0       0       0
      27           200.0           100.0           100.0       0       0
      28             0.0             0.0             0.0       0       0
      29            50.0             0.0             0.0       0       0
      30           100.0             0.0             0.0       0       0
      31             0.0            50.0             0.0       0       0
      32            50.0            50.0             0.0       0       0
      33           100.0            50.0             0.0       0       0
      34             0.0           100.0             0.0       0       0
      35            50.0           100.0             0.0       0       0
      36           100.0           100.0             0.0       0       0
      37             0.0             0.0            50.0       0       0
      38            50.0             0.0            50.0       0       0
      39           100.0             0.0            50.0       0       0
      40             0.0            50.0            50.0       0       0
      41            50.0            50.0            50.0       0       0
      42           100.0            50.0            50.0       0       0
      43             0.0           100.0            50.0       0       0
      44            50.0           100.0            50.0       0       0
      45           100.0           100.0            50.0       0       0
      46             0.0             0.0           100.0       0       0
      47            50.0             0.0           100.0       0       0
      48           100.0             0.0           100.0       0       0
      49             0.0            50.0           100.0       0       0
      50            50.0            50.0           100.0       0       0
      51           100.0            50.0           100.0       0       0
      52             0.0           100.0           100.0       0       0
      53            50.0           100.0           100.0       0       0
      54           100.0           100.0           100.0       0       0
*SET_NODE_LIST_TITLE
moving
$#     sid       da1       da2       da3       da4    solver       its         -
         2       0.0       0.0       0.0       0.0MECH      1                   
$#    nid1      nid2      nid3      nid4      nid5      nid6      nid7      nid8
        31        28        37        40        34        43        46        49
        52         0         0         0         0         0         0         0
*END

[Chris Quan]

It seems that you have to use MPP to run this model with *CONTACT_AUTOMATIC_SINGLE_SURFACE_TIED.

Also, you need to scope the slave faces to All Faces of the model or Both Faces on their interface. Otherwise it won't be bonded.

Finally, in WB LS-DYNA bonded contacts will be automatically created under Connections after geometry has been imported to Mechanical GUI and the distance between two faces is less than the specified tolerance. It may not be necessary to use Keyword Manager to define bonded contacts. Contact Properties can be inserted to modify the behavior of these bonded contacts such as type, penalty stiffness, etc.