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Hi All, I am currently going through the LS-DYNA example of the dam-break wave generated by SPH particles () and I was wondering if there is a way to extract along a vertical line the free-surface elevation over time? Or conversely a 3D output of the free-surface of the SPH particles over time. Thank you all for your time and consideration!

It looks like the new version of Hyperworks has a user interface. Looks a lot cleaner.

Hi, I'm modeling hypervelocity impact (2.22 km/s tungsten carbide sphere on HSLA-100 steel) with coupled thermal-structural analysis using S-ALE (Structured ALE) mesh. Initial Attempt & Issue: I first tried the implicit thermal solver using: - *CONTROL_SOLUTION (Thermal-Structural Analysis) - *CONTROL_THERMAL_NONLINEAR - *CONTROL_THERMAL_SOLVER - *CONTROL_THERMAL_TIMESTEP However, I observed physically unrealistic temperature rates (dT/dt on the order of billions of °K), which is physically impossible. I switched to the Explicit Thermal Solver (*CONTROL_EXPLICIT_THERMAL_* cards) as an alternative, but encountered a fatal initialization error. Current Error: ``` forrtl: severe (164): Program Exception - integer divide by zero Image PC Routine Line Source lsdyna_mpp_dp_imp 00007FF731E6B4CC XPLCTH_INIT 1148 dyn20x.F ... ``` The crash occurs during initialization (`XPLCTH_INIT`), suggesting a division by zero in the thermal data setup. Specific Questions: 1. Explicit Thermal Setup with S-ALE: For cards like `*DATABASE_ALE`, `*CONTROL_EXPLICIT_THERMAL_INITIAL`, and `*CONTROL_EXPLICIT_THERMAL_OUTPUT`, the manual states SETID can be left blank for "all parts," but LS-PrePost/LS-DYNA requires an integer. Since S-ALE mesh elements are generated internally at runtime (not predefined in `*ELEMENT_SHELL`), I cannot reference them via traditional `*SET_SHELL_LIST`. - How do I properly define SETID for S-ALE domains in these cards? Should I use `*SET_MULTI_MATERIAL_GROUP` instead? 2. Phase Change Modeling: My material definition includes `*MAT_THERMAL_ISOTROPIC_PHASE_CHANGE` for the steel target (solid-to-liquid). Does the Explicit Thermal Solver support phase change energy (latent heat), or is this capability restricted to the implicit thermal solver? If supported, are there specific considerations for S-ALE multi-material groups? 3. Divide-by-Zero Cause: The error trace points to `XPLCTH_INIT` (dyn20x.F:1148). This typically indicates zero thermal mass (density × specific heat) in a thermal part definition. Given that my vacuum/void material (`*MAT_ALE_VACUUM`) has near-zero thermal properties, could this be triggering the crash? Should vacuum regions be excluded from the thermal solver via `*SET_PART_LIST`, or is there a minimum non-zero thermal density requirement? Model Context: - 2D Axisymmetric S-ALE mesh (fine resolution) - 3 ALE Multi-Material Groups: HSLA-100 Steel, Tungsten Carbide, Vacuum - Thermal properties defined via *MAT_THERMAL_ISOTROPIC and *MAT_THERMAL_ISOTROPIC_PHASE_CHANGE - Using MPP R14.1.1 on Windows Keyword file attached for reference: Any guidance on proper explicit thermal initialization with S-ALE and phase change setup would be greatly appreciated. Thanks, Amrith

Hi @janeshka, It's a little difficult to help you figure out the problem without having more details. How do you know your current material is not behaving correctly? What do you expect vs what is happening? Have you read about this material in the LS-Dyna Material Manual? (link below, page 429) I believe this dyna support page will help a lot My theory is that something is off with how dyna is calculating your axes from AOPT. Try setting ATRACK=1 in *Control_Accuracy. You can also do a sanity check by creating a single element model with this material and defining your coordinate system on that element, perform your compression, and see if the material is behaving correctly. This is actually what I would do so you can be 100% sure if the material is the problem or not.

@sandon101 You may have seen this already, but these examples may help fine-tune your simulation to remove the noise: What results are noisy and what method are you using to obtain them?

Yeah, I believe that second option with the submit form is what you are looking for. This link should point you here:

How to model composite materials in LS-Dyna seems to be a question for many people. I've compiled some sources to perhaps help with this topic:

@geardyn-1 This one>

Hello everyone! I'm trying to replicate a simulation described in: . As a precursor to this, I'm running a number of smaller simulations to get familiarized with LS-Dyna (I'm a simulation engineer, but haven't used LS-Dyna so far). They're all solving a very simple case: a spherical indentor with a diameter of 10 mm (modelled with 1 mm shells, rigid) is being pressed into a 120 mm by 120 mm DC04 sheet with a thickness of 1 mm (modelled with 1x1 shell elements, element type 25 as described in the paper linked above). From reading the paper it's clear that the authors used Chaboche-Roussilier kinematic hardening. Having read recently that MAT036 with Chaboche-Roussilier was apparently broken for some time, I chose to use MAT133 (Barlat yield 2000). As the isotropic hardening properties of the DC04 material used by the authors were not disclosed, I opted for a simplified approach assuming no in-plane anisotropy (R00=R45=R90,SY00=SY45=SY90) and isotropic hardening according to the BaoSteel curve with a yield stress of 163 MPa. So far everything worked magnificently, but with the addition of kinematic hardening I am running into a problem that leaves me baffled. The authors of the paper pointed out that they made use of a single backstress term of the C-R model, with A=80 MPa, C=25500 MPa. Now, I realize that by assuming certain values for the isotropic hardening I will certainly not be able to fully replicate their results - however, I'd still like to make use of the kinematic hardening parameters they used. I did a number of test runs with (A, C) going from (0, 0) to (80, 2500) - all of which were successful. However, setting C to 25500 (or even 5000 or 7500 for that matter) invariably leads to a plasticity convergence failure very early in the simulation, at very benign deformations and strains. I've been banging my head against this problem for the last 2 weeks, playing around with contacts, control parameters, el. formulations and material parameters, but I cannot resolve it. I would have thought nothing of it if the model failed towards the end of the aforementioned indentation case at 40%, 50% strain, but I find it very odd indeed that it should fail basically as soon as plasticity is activated. I've attached to this post the last working version of the indentation case (A=80, C=2500 instead of the desired 25500). Perhaps somebody could help me understand: 1) Why the plasticity model fails right away at very low plastic strains or successfully completes (the usual case being either a fundamental error breaking it at the beginning or a difficult model failing at high strains... thus very different from my problem)? 2) Is there perhaps a way to make use of the other C-R terms to "ease" the model into kinematic hardening? Some combination of parameters that would lead to an "equivalent" value of (A, C) closer to (80, 2500) at low strains and closer to (80, 25500) at high strains? 3) Is there any other way to resolve this issue and get robust combined kinematic and isotropic hardening? Looking forward to all replies! Best regards, Leibhussar Attachment : El25Barlat.k

Hi everyone, I need to group back all my single ASCII files (e.g., abstat, nodout, glstat, matsum, ...) in a single binout000* file. I know from here () that it is possible to do the opposite, i.e., extrapolating the ASCII files from the binout, but I can't find anything about the reverse. I'm facing this issue because I, unfortunately, deleted the binout files after the simulations, keeping only the ASCII ones 😣. I could re-run the simulations, but it takes time. Can l2a.exe do what I want, or does anybody have other walkarounds for this problem?

Welcome to the forum! So are you building your model yourself or using something previously made? If you are creating something, it will be easy to keep consistent units. If you are using something somebody else created, you need to ask them what unit system they were using. Here is a post that might help explain things. It seems like you've got your units of time jumbled up a bit. What you are trying to do here is validate your simulation to an experimental test. What you want to do is replicate the experimental test boundary conditions as close as you can using modeling techniques in LS-Dyna. Then you will need to assign a section and material to your dogbone. Materials in LS-Dyna are not as simple as "I want this to be steel", they are mathematical functions that behave according to the parameters you input. What is the experimental dogbone made of? Also here's a thread that might help. Unfortunately, the "dynamat" link is no longer working. I'm going to see if I can find it somewhere.

Sure you can actually download the final models for each video here: Changes in LS-Dyna versions over the years can cause small problems. Let me know if you still are having issues.

@john of course my mistake Looks like there’s a couple on YouTube. I’d focused on making it as simple as possible. If you know the drop tower height you can calculate the velocity at impact by hand, and prescribe that to your sim with *Initial_velocity. Just position the impactor and composite part close together an either constrain the composite part vertical motion or add a constrained contact surface below.

Have you considered alternatives? Try modeling the curve using curve fitting online. Very convenient and intuitive tool (free).

@kemoo it's difficult to tell whether the increased force is coming from the actual lattice structure being too stiff or from a factor in the boundary conditions/force output. Something else you can do to check that your forces are being output correctly is to use a cross-section set on one of the impactors instead of looking at contact force. This is the most full-proof way to check because contact forces can be influenced by all kinds of things ranging from contact parameters to mesh size. I made a diagram below but the gist is to change one of the impactors to a stiff deformable material so that you can get forces from a layer of solid elements within that impactor. You will then need to either make a top layer of rigid shell elements attached to this in order to drive your motion or create a node set if you are using boundary prescribed motion. I've also included a link describing various *database cards and how to set them up in a youtube video. < span style="color: #666;"> Attachment :  force_output_help.JPG