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<p class="isSelectedEnd">I have a simulation that involves shell elements and SPH particles. According to the documentation, setting SHLTHK=0 under CONTROL_CONTACT means that the shell thickness is not considered in contact calculations. I used the same setting and ran the simulation. However, the messag file indicates that many SPH particles have initial contact.I do not understand how initial contact can occur if the shell thickness is ignored. I should mention that the coordinates used for geometry/mesh generation were defined such that there was no penetration before starting the simulation. Could someone help me understand why these initial contacts are being detected and how to resolve this issue when the shell thickness is ignored in the contact definition?</p><p>Thank you in advance.</p>

<p>Hello everyone,</p><p>I encountered a possible inconsistency when setting the concentration boundary condition for species transport in LS-DYNA.</p><p>The keyword *ICFD_BOUNDARY_PRESCRIBED_<wbr>SPTRANSP_CONC appears differently in the LS-PrePost keyword interface and in the LS-DYNA manual.</p><p>In LS-PrePost, the keyword is shown as a two-line structure:</p><p>the first line defines the PID</p><p>the second line contains the LCID values</p><p></p><p>However, in the LS-DYNA manual, the keyword is documented in a single-line format where PID, LCID and CONC fields appear together.</p><p></p><p> </p><p>Because of this difference, I observed the following behaviour:</p><p>If I follow the format shown in LS-PrePost, the solver produces an error:</p><div><div><div><div><div><div><div><div> </div><div><div><div id="m_2277478720517859887gmail-code-block-viewer" dir="ltr"><div><div>input conversion error<br>forrtl: severe (64) </div><div></div></div></div></div></div></div></div></div></div><div><div> </div></div></div></div></div><p>and the simulation cannot start.</p><p></p><p> </p><p>Even if I instead follow the manual format and remove the second line, the simulation runs but the concentration boundary condition does not seem to be applied. In this case:</p><p>the inlet concentration remains zero</p><p>residuals for the scalar transport equation are not computed<br></p><p><br></p><p>I also noticed a similar mismatch for another keyword related to species transport:</p><div><div><div><div><div><div><div><div> </div><div><div><div id="m_2277478720517859887gmail-code-block-viewer" dir="ltr"><div><div>*ICFD_MODEL_SPECIES_TRANSPORT</div></div></div></div></div></div></div></div></div><div><div> </div></div></div></div></div><p>where the format in the LS-PrePost interface does not fully match the manual description.</p><p>Because of this inconsistency I am currently unable to run simulations that require inlet concentration boundary conditions for species transport.</p><p>Could anyone clarify:</p><p>The correct keyword format  *ICFD_BOUNDARY_<wbr>PRESCRIBED_SPTRANSP_CONC</p><p>whether this difference between LS-PrePost and the manual is expected</p><p>or if this might be a bug?</p><div>My LS-DYNA version: R16 SMP and LS-PrePost version: 4.12.6</div><p>Thank you so so so much for any guidance! </p>

<p>Hello everyone,</p><p>I encountered a possible inconsistency when setting the concentration boundary condition for species transport in LS-DYNA.</p><p>The keyword *ICFD_BOUNDARY_PRESCRIBED_<wbr>SPTRANSP_CONC appears differently in the LS-PrePost keyword interface and in the LS-DYNA manual.</p><p>In LS-PrePost, the keyword is shown as a two-line structure:</p><p>the first line defines the PID</p><p>the second line contains the LCID values</p><p></p><p>However, in the LS-DYNA manual, the keyword is documented in a single-line format where PID, LCID and CONC fields appear together.</p><p></p><p> </p><p>Because of this difference, I observed the following behaviour:</p><p>If I follow the format shown in LS-PrePost, the solver produces an error:</p><div><div><div><div><div><div><div><div> </div><div><div><div id="m_8717735918342925683gmail-code-block-viewer" dir="ltr"><div><div>input conversion error<br>forrtl: severe (64) </div></div></div></div></div></div></div></div></div><div><div> </div></div></div></div></div><p>and the simulation cannot start.</p><p></p><p> </p><p>Even if I instead follow the manual format and remove the second line, the simulation runs but the concentration boundary condition does not seem to be applied. In this case:</p><p>the inlet concentration remains zero</p><p>residuals for the scalar transport equation are not computed<br></p><p> </p><p>I also noticed a similar mismatch for another keyword related to species transport:</p><div><div><div><div><div><div><div><div> </div><div><div><div id="m_8717735918342925683gmail-code-block-viewer" dir="ltr"><div><div>*ICFD_MODEL_SPECIES_TRANSPORT</div></div></div></div></div></div></div></div></div><div><div> </div></div></div></div></div><p>where the format in the LS-PrePost interface does not fully match the manual description.</p><p>Because of this inconsistency I am currently unable to run simulations that require inlet concentration boundary conditions for species transport.</p><p>Could anyone clarify:</p><p>The correct keyword format  *ICFD_BOUNDARY_<wbr>PRESCRIBED_SPTRANSP_CONC</p><p>whether this difference between LS-PrePost and the manual is expected</p><p>or if this might be a bug?</p><div>My LS-DYNA version: R16 SMP and LS-PrePost version: 4.12.6</div><p>Thank you so so so much for any guidance! </p>

<p>Hello,</p><p>Is a quadratic 3 noded bar element available in LS-DYNA?</p><p>Thanks.</p>

<p>Received new license file recently and tried to update it on a previously working server. Got the following error message:<br><br></p><div>******************************<wbr>******************************<wbr>*********</div><div>LSTC license server version 77918 started at Wed Jun 3 10:21:30 2026</div><div>******************************<wbr>******************************<wbr>*********</div><div>Using configuration file /opt/lstc/server_data</div><div>ERROR: the host id(s) of this machine ( 50327FA0 )</div><div>not found in the license file /opt/lstc/server_data</div><div> </div><div>It's confirmed the 50327FA0 id is in the server_data file. I would really appreciate suggestions on how to debug/solve this.</div>

<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Hi,</p><p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">I have Ansys LS-DYNA 2025 R1 (v251) installed on Windows, with solver version SMP R14.1.1 double precision.</p><p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">I am implementing a custom nonlinear constitutive model (resilient modulus k-theta) using a UMAT subroutine and need the Windows usermat package containing:</p><ul class="[li_&]:mb-0 [li_&]:mt-1 [li_&]:gap-1 [&:not(:last-child)_ul]:pb-1 [&:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3"><li class="font-claude-response-body whitespace-normal break-words pl-2">dyn21.F / dyn21b.F<li class="font-claude-response-body whitespace-normal break-words pl-2">include files (.inc)<li class="font-claude-response-body whitespace-normal break-words pl-2">static libraries (.lib)<li class="font-claude-response-body whitespace-normal break-words pl-2">Windows build script (nmake makefile)<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Could you please advise on the correct procedure to obtain this package for my installation?</p><p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Compiler environment: Intel oneAPI (ifort), Microsoft Visual C++ 2019.</p><p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Thank you very much.</p><p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Eloísa Castilho </p>

<p>Hi everyone, I'm striking a rigid wall. LS-Dyna Workbench.<br>The impact is on the bolts. The bolt and nut have bonded contact. But when the impact occurs, the bolt slips through the nut.</p><p></p><p>I'm also getting penetration messages:</p><div id="paraDiv" class="text-color-primary" style="display: inline;"><p id="paragraphData" class="paragraphText text-color-primary" style="font-size: 12px; display: inline;">23098 initial penetrations were found for interface        763<br>     57 initial penetrations were found for interface        646<br>     70 initial penetrations were found for interface        649<br>     78 initial penetrations were found for interface        652<br>     32 initial penetrations were found for interface        655<br>      62 initial penetrations were found for interface        847<br>     27 initial penetrations were found for interface        658<br>   14564 initial penetrations were found for interface        712<br>      60 initial penetrations were found for interface        850<br>      50 initial penetrations were found for interface        865<br>      60 initial penetrations were found for interface        880<br>   11442 initial penetrations were found for interface        730<br>      60 initial penetrations were found for interface        841<br>   14557 initial penetrations were found for interface        718<br>      60 initial penetrations were found for interface        844<br>      48 initial penetrations were found for interface        859<br>   14514 initial penetrations were found for interface        724<br>      48 initial penetrations were found for interface        862<br>   14504 initial penetrations were found for interface        706<br>    122 initial penetrations were found for interface        673<br>     741 initial penetrations were found for interface        823<br>    107 initial penetrations were found for interface        676<br>     551 initial penetrations were found for interface        838</p></div><p>Help please.</p>

<p><p><p>I have read the user manual on user defined materials but it doens't address the following use case so I thought I would post here. </p><p>Is it possible define a user material that calls a predefined LS-DYNA material model? If so what would the syntax look like to accomplish this? </p><p>For example let's say I want to introduce a topology optimization variable as part of a user defined material model and I want to use a predefined elastoplatic model which already exists in LS-DYNA in combination with said TO variable. I am trying to take advantage of the material model that already exists rather than reimplementing it myself. </p><p>Any help or insight would be greatly appreciated. Thanks in advance. </p></p></p><p>Update 6/6/26:</p><p><p><p> A small update. I remembered being able to view the signatures of object files .o or .a files with command line tools like nm or objdump. So as a small first step I can at least view the function names available in precompiled object files. Which I believe correspond to the material subroutine names. However, this is not the complete function definition with variable names in the correct order but it is a start. It is also probably reasonable to assume that the variable ordering in the card definitions in the user manual are the same order as the variables in the function call. Although it will probably get a little tricky with cards that can be repeated and other such options. But it is a start...</p></p></p><p>Update 6/10/26:</p><p>After downloading and reviewing the object version of LS-DYNA and the accompanying Fortran files for defining the user defined materials I actually think the calls to the existing material models will look more like what is found in those Fortran files, e.g.,</p><p>   call umat41 (cm(mx+1),eps,sig,epsp,hsv,dt1,capa,eltype,tt,<br>     .   temper,failel,crv,nnpcrv,a(lcma),qmats,elsiz,idele,reject)</p><p>Of course instead of calling umat41 it would be the material model you want to use. But now I'm having a hard time finding the function names of the existing material functions in the object files as suggested above. I wonder if it as simple as "matxxx"....?</p>

<p>Hello, I am getting an error as shown below when trying to use sensor_define_element_set.    in the below parameter, if I set comp = PRIN1, below error shows up.   if I set it to XX, YY, ZZ, it doesn't</p><p>I have database_elout, database_history_solid and control_output all properly set.   If anyone can think of anything causing this, I would realy appreciate it.  </p><p> </p><p></p>

<p>Hello all, I'm hoping to find some help here. Hopefully I am just misunderstanding the physics of what i going on.</p><p>So i set up an Explicit Dynamics sim of a rotating shaft coupling impacting a guard. The axis of the coupling is angled 45deg off the YZ plane and 30deg off the XY plane. Coupling is set to rotate around the coupling center axis at 2000rpm and translate 2000in/sec in the global Y direction. Or so i think. But the solution is showing the coupling rotating as expected, but translational movement is mostly in the X global direction with some translation in the intended Y global direction. </p><p>Attached are some pictures of the setup. I'm sure there will be questions and more information i have not thought to answer and provide, so please ask.</p><p>My question is why is the coupling translating mostly in X instead of Y as intended? Is it because i am misunderstanding the effects of angular momentum?</p><p></p><p></p><p></p><p></p><p> </p>