Welcome to the LS-DYNA Product Space

<p data-pm-slice="0 0 []">Hello,</p><p>I encountered the following error while running my simulation on an HPC  using LS-DYNA R12:</p><p>*** Error 41434 (SOL+1434)</p><p>Error encountered in SPH neighborhood search routine.</p><p>Please check mes#### file for detailed information.</p><p>Based on another Q&A on this forum, I increased NMNEIGH in *CONTROL_SPH and ran the simulation again. However, the simulation terminated with the same error. In fact, the error occurred even earlier than before.First run: error occurred at 1.7 s of simulation time. Second run (after increasing NMNEIGH): error occurred at 1.2 s of simulation time. I am using LS-DYNA R12.</p><p>Could someone please help me understand: What is the most common cause of this error?</p><p>What is the solution?</p><p>Is there a way to prevent the simulation from terminating when this error occurs, or is the termination unavoidable?</p><p>Any suggestions would be greatly appreciated.</p>

<p>Hello,</p><p>I am currently learning LS-DYNA and trying to simulate an end milling operation with chip formation.</p><p>I have modelled the milling cutter as a rigid body and the workpiece as a deformable body. However, I am facing difficulties in defining the correct contact interaction required for material removal. The simulation also terminates with errors such as "Energy error too large" and "General solver error."</p><p>I have attached screenshots of my model setup, contact definition, and the solver errors.</p><p>Could anyone please guide me on:</p><p>The recommended workflow for end milling simulations in LS-DYNA.</p><p>The correct contact definition for chip formation.</p><p>The essential Control Cards, Database Cards, and Keywords required for this type of simulation.</p><p>Any official tutorials or benchmark examples for metal cutting using LS-DYNA.</p><p>Thank you for your time and guidance.</p>

<div data-index="122">Reviewing the System Coupling User's Guide (Release 2026 R1), the list of supported coupling participants includes Mechanical/Mechanical APDL, Fluent, CFX, Forte, Electronics Desktop/Maxwell, FMU, Thermal Desktop, Rocky, and Files - but LS-DYNA does not appear in this list.</div><div data-index="122">Therefore, if possible, I'd like to clarify the current status of coupling between Ansys Rocky (DEM) and LS-DYNA.</div><div data-index="122"> </div><div data-index="123">So far, I've found clear documentation for:</div><div data-index="123"> </div><div data-index="125">- Rocky ↔ Ansys Mechanical (1-way and 2-way, via System Coupling)</div><div data-index="126">- Rocky ↔ Ansys Fluent (CFD-DEM)</div><div data-index="127">- LS-DYNA participating in System Coupling with Fluent and MAPDL</div><div data-index="128">- A sequential/homogenization workflow linking Rocky → Multiscale.Sim → LS-DYNA (Cybernet's Multiscale.Sim add-in), which is one-way and does not preserve time-resolved feedback between the two solvers</div><div data-index="129"> </div><div data-index="130">My specific questions:</div><div data-index="131"> </div><li data-index="132">Is direct two-way co-simulation between Rocky and LS-DYNA officially supported today (2026 R1/R2)? If so, is it via System Coupling, or another mechanism?<li data-index="133">If supported, is LS-DYNA's participant status in System Coupling still a beta/experimental feature for this type of coupling, or has it reached production maturity?<li data-index="134">Are there known limitations regarding the time-step mismatch between Rocky's DEM solver and LS-DYNA's explicit time integration (microsecond-scale)? Is subcycling or another mechanism used to reconcile this?<li data-index="135">Is there a reference case, tutorial, or technical manual (beyond the general System Coupling User's Guide) that documents this specific Rocky↔LS-DYNA workflow?<li data-index="136">What licenses/executables are required (e.g., a special LS-DYNA build with SyC DLLs, as required for LS-DYNA↔Fluent coupling)?<div data-index="138">Any pointers to official documentation, technical support cases, or example projects would be greatly appreciated.</div><div data-index="139">Thanks in advance!</div>

<p>i am using ansys explicit dynamics to simulate blasting in concrete block . I want to calculate the eroded volume( vlume of material that has been blasted), how can i do so?</p>

<p>Hello, does anyone on the Ansys side know when the LSDYNA student version will be updated?  The current version will end soon (July 31st 2026). </p><p> </p><p>Thank you!</p>

<p>Hello all,</p><p>I am trying to write a UMAT that requires the total strain from the previous cycle as well as needing to store internal stress modes for the material model I am trying to implement. Setting IHYPER = 1 and LHV = (some number) in the keyword seems to wipe hsv(1) - hsv(9) at the beginning of every cycle.</p><p>How do I make use of the deformation gradient and save internal stress modes at the same time?</p><p>Many thanks,</p><p>K</p>

<p>Hi,</p><p>I perform a implicit static analysis and use *DATABASE_BINARY_D3MAX/*DATABASE_MAX_SOLID_SET to output the maximum stress of a target solid element set, and then perform post-processing in LSPP. </p><p>The issue I encounter is that, for the same set, the location and value of the maximum stress from d3max and d3plot are different:</p><p>- In d3max, the maximum stress is 853 MPa, with element ID = 19651.</p><p>- In d3plot, the maximum stress is 932 MPa, with element ID = 19114.</p><p>I would like to know what causes this discrepancy.</p><p>Thank you very much.</p><p></p><p></p>

<p>https://www.researchgate.net/publication/315973637_Development_of_a_Steel_Brace_with_Intentional_Eccentricity_and_Experimental_Validation<p class="isSelectedEnd">Hi everyone,</p><p class="isSelectedEnd">I am trying to numerically reproduce the experiment presented in the attached paper.</p><p class="isSelectedEnd">I first modeled the specimen in Abaqus as a 2D model, using constraints to represent the rigid elements. Now I am trying to build the same model in LS-DYNA, but I am having difficulties modeling the rigid elements correctly.</p><p class="isSelectedEnd">I have tried using *CONSTRAINED_NODAL_RIGID_BODY with pinned supports (free rotation), but the entire assembly behaves as a single rigid body. I also tried modeling the rigid elements with beam elements having a very high stiffness, but the results are still differ significantly from those obtained with Abaqus and the experimental data.</p><p class="isSelectedEnd">What is the recommended approach in LS-DYNA for modeling rigid elements between two nodes while maintaining pinned boundary conditions? Is *CONSTRAINED_NODAL_RIGID_BODY the appropriate choice, or is there a better approach?</p><p class="isSelectedEnd">Any suggestions would be greatly appreciated.</p><p>Thank you!</p></p>

<p data-pm-slice="0 0 []">Hello,</p><p>I am new to MPP LS-DYNA and have a few questions. I create my model on a single processor (a regular PC), but it will eventually be run on a cluster, so I am trying to understand the MPP-related settings and keywords.</p><p>a) While reading the documentation about output files, I came across the BINARY option for several output databases (I have attached a screenshot to illustrate my question). So far, I have always used the default value for BINARY.The documentation states:</p><p>Flag for binary output...</p><p>EQ.1: ASCII file is written. This is the default for shared memory parallel (SMP) LS-DYNA executables.<br>EQ.2: Data written to a binary database binout, which contains data that would otherwise be output to the ASCII file. The ASCII file in this case is not created. This is the default for MPP LS-DYNA executables.<br>EQ.3: ASCII file is written, and the data is also written to the binary database (NOTE: MPP LS-DYNA executables will only produce the binary database).</p><p>Since EQ.2 is listed as the default for MPP LS-DYNA, does this mean that when I run my existing model.k file on the cluster, the output will automatically be written in binary format? Or should I explicitly set BINARY= 2 because I know the simulation will be run using the MPP executable?</p><p> </p><p>b) When LS-DYNA writes binary output files (such as binary file), can they be read directly in LS-PrePost?</p><p> </p><p>c) Under the CONTROL keywords, I noticed *CONTROL_MPP_DECOMPOSITION_FILE_{OPTION}. From the documentation, my understanding is that this keyword can either: create a decomposition file and terminate the simulation, or read a previously generated decomposition file. If I do not use this keyword at all, what happens? Will LS-DYNA automatically perform the domain decomposition and continue running the simulation, or is there another default behavior?</p><p> </p><p>d)would you please explain the usage of this keyword:  CONTROL_MPP_DECOMPOSITION_FLAG_STRESS_STRAIN_CURVE ?</p><p> </p><p>e ) Do you happen to have any tutorials for learning MPP LS-DYNA?</p><p>Thank you very much for your time and help.</p><p></p><p> </p>

<p>Hi all,</p><p>How can I create free field boundary condition without using *CONSTRAINED keyword. I cannot use these periodic boundary conditions as I have geometry effects. I tried Non-Reflecting Boundaries but they cause boundary effects. Any insights would help a lot.</p><p>Best,</p><p>Muhsin</p><p> </p>