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Hello dear professionals. I have another problem, sorry. I need help. I am modeling a test model (downloaded from the forum) before moving on to a complex one. The task of drilling a metal plate. The problem is that I don't have shavings. There are no chips with any material, any fracture model. Most likely the problem is not in the material. Help find her. When drilling, the body behaves like a very elastic one: (image attached). DOWNLOAD ANIMATION To explain all the settings is very long, so I attached the K-file DOWNLOAD K-FILE. I will be very grateful if you help, I can not find the reason for a very long time. < span style="color: #666;"> Attachment : 28-07-2022-1659032817-mceclip0.png

Hello, Thanks for your answer. I am trying form like that in the photo and attached the step file for rollers.In my k file and step format model is in link below. There are no contacts between parts. Only i give automatic contact surface to surface by their part id's. For step model For k file < span style="color: #666;"> Attachment :  Sheet-Form.png

Is the red air domain a solid? I'm not sure if it would work but you might be able to use *Contact_surface_to_surface_thermal and use segment sets between the red and blue. I'm not sure if that would work since the meshes will be initially penetrating. Also, have you tried changed *Control_Solution SOLN to be thermal only? I only say this because it doesn't seem like you are interested in any kind of structural analysis, only the thermal. Also, here's a deep dive on this topic within Dyna that might be of use:

Hi @ana, @icebreakersours is laying down some fundamental FEA advice. A lot really comes down to your understanding of what "should be normal" in your case. And that will come from reading and experience. Now to applications. You can try adding viscous damping (VDC) to your contact instead of global damping. This is usually a better first approach then applying global damping so that you don't negatively affect the other parts of your simulation that might be performing perfectly fine. I've used VDC=40 in the past for certain situations. From the help page below: "Viscous Damping, VDC (Card 2, *CONTACT_option)The viscous contact damping parameter, VDC, on card 2 of *CONTACT is zero by default. Originally, contact damping was implemented to damp out the oscillations that existed normal to the contact surfaces in sheet metal forming simulations. It has been found that contact damping is often beneficial in reducing high-frequency oscillation of contact forces in crash or impact simulations. Viscous Damping RecommendationsIn contacts involving soft materials such as foams and honeycombs, frequent instabilities exist due to contact oscillations. Using a value of VDC between 40-60 (corresponding to 40 to 60% of critical damping), it is found that the model stability improves; however, it may be necessary to reduce the scale factor for the time step size. Generally, a smaller value of 20 is recommended when metals, which have similar material constants, interact." Alternatively, forces from contacts can be so varied depending on the type of contact, parameters, or the entities that you are using in the contact (segments vs parts vs nodes etc). So something else you can try is to take your force directly from the bean that is contacting the surface using elout. This thread might help explain how to set up *Database_history_beam so that you can access elout data.

Hi ANA, I will come right out and say I'm not exactly one of the experts 'round these parts, but I do have some suggestions. To my understanding these sorts of issues can have a ton of reasons, the man himself answered a question about something similar a little while ago: If you hadn't read the post already. One comment suggested applying proper filtering and mentioning it in your discussions. There are two things I wanted to mention were how timestep and/or more direct contact stiffness control can do a lot for these things. I didn't see this said directly in the dynasupport page for contacts, but there could be a benefit in reducing the TSSFAC in *CONTROL_TIMESTEP, or changing the SFS and SFM values in your contact card. These could be particularly important if you have dissimilar meshes if I remember correctly. I'm not sure at exactly which time it is mentioned, but these videos go into it way deeper than I can: I hope some of that helps!

Hi @mhmtk98, How new are you to LS-Dyna? You should try to get more familiar with the basics before undertaking a complex simulation like that, especially if it's for a thesis. The main things that you will need to understand for a simulation like that would be: Learn about the vehicle and barrier model that you have and if it would be appropriate for what you propose to study for your thesis Learn how to setup any outputs that you wish to measure Setup your boundary conditions like vehicle/barrier motion (*initial velocity vs boundary prescribed motion, contacts etc) Learn how to extract results from the simulation through post-processing I would suggest going through some training material and reinforcing it with some examples that you can recreate.

Ty very much guys for answers. I have already DL this version : " LS-PrePost-4.3.38-x64-30Jan2019_setup " And i am currently following this YT tutorial to hang on PrePost interface. and the format of the LS-Dyna files. What's so special with the format ? To be honest, i feel a little lost about LS-Dyna/PrePost. I've used until now Cast3M/Abaqus/FEniCS for FEM. But LS-Dyna looks very different than these stuffs. I mean, what's the difference between LS-Dyna and LS-Prepost ? Tell me if i'm wrong, but is LS-Dyna a type of "code", or something like a library, that can be used trough LS-Prepost which is a graphic interface to run calculations ? Well, it's not clear for now ^^'

Dear everyone, I want to simulate a simple 2D flow around a cylinder case using ICFD and user defined mesh, but when I run the source file with LS-DYNA R11 SMP, (source file address ), get this error, Error 10928 (KEY+928) The CFD meshing toolset is not available in this executable. can you help me solve this problem?

Hi all, I am very new to LS-Dyna (but am familiar with other FEA software/solvers - such as Hypermesh) and have started by following along with tutorials and other examples to get the hang of it. I am currently working through the "LS-Dyna Ball and Block" tutorial on YouTube by the channel Unpopular Mechanics (part 2 here: ). I am fairly certain I followed every step and input exactly as described in the tutorial videos, but when I attempt to run the file to obtain results, I am met with a "negative volume in solid element" error and it terminates. (My animation with the d3plot looks nothing like what is then shown in the YouTube video - it is cut short at only 9 frames.) I have looked through some other posts in this forum about negative volume errors but was unable to find anything useful for my situtation, so am posting this in the hopes someone may have some helpful pointers. My questions are then: - has anyone tried this same tutorial and had this same error that causes the simulation to end prematurely? - what does the "negative volume" error mean? Is there something that can be modified in the material or element properties that could help with resolving this error? Thank you in advance for any insight you can provide. I really appreciate any help.

I am a first-year graduate student researching the nature of sand-particle collisions with ductile surfaces. About a month ago, my research group obtained an LS-Dyna license, and since then, I have been toying with the software, trying to create basic collision models (elastic sphere colliding with elastic surface kind of thing). I am the first member in the group tasked with learning how to use the software, and I feel kind of stuck. I have investigated many of the Dyna examples from dynaexamples.com and have watched many YouTube videos, but that has not gotten me to the desired general understanding of the software and its underlying mechanisms. My advisor recently told me we had enough funding for me to get some official training on the software. Do you guys have any advice on what training is most helpful? Right now, we are considering the training offered directly by ANSYS listed here along with these third-party training groups. I will add that my background up to this point has been in pure physics, so I do not yet have a deep understanding of FEM or general structural mechanic (though I am currently taking a course in continuum mechanics). If you feel that I will need to do some independent study before any of the Dyna training courses will be of use, that information would be very helpful as well.

Hi @djsburra, That really stinks, they must have updated their student license limitations this year. Honestly, it never hurts to contact them and ask? You could get in touch with somebody in your department and see if there is any budget to pay to a limited license. Alternatively, you can use something else for meshing. Depending on how advanced you are going, you could use LS-PrePost's built-in meshing tools. It won't be as glamorous, but it can get the job done. If you choose to go this route let me know and I can try to get you started and acclimated with it. There are other free meshing software like IA-FEMesh (link below) which are even less intuitive but better at things like hexahedral meshing

Hi @nikhillonkar92, So you are on the right path. Mass scaling is determined using *Control_timestep where at the minimum you need to define TSSFAC and DT2MS. TSSFAC is just the scale factor for the computed time step which is 0.9 by default. This can be lowered with higher energy simulations like explosions, but generally it's best just to leave it at 0.9. DT2MS is where you input your desired minimum timestep for your simulation. So mass will be added to any elements that drop below this timestep in order to compensate. Also, it's important to know that negative and positive values for DT2MS will behave differently. Negative will only add mass to elements that drop below that threshold like I described above (I recommend this), Positive will add or remove mass from all elements to make the timestep the exact same for all elements of the model. A lot more detail regarding mass scaling can be found here: Additionally, this link goes through how time step is calculated if you want some background on that front:

Well I missed a pretty obvious resource. Short answer is with MAT_CWM and CWM thermal. Then combined with either envyo (from dynamore) or some kind of script, create THERMAL_WELD_TRAJECTORY. If I end up going this route, and making a python script Ill put the link to the github repo in a reply here.

In addition to all of that the file you posted looks like a .stl file (laser scan data?) So ANSYS may or may not accept that as geometry. If it does, be wary because ANSYS can create some really bad meshes without proper control. (bad mesh -> bad equations -> bad results). So check the element quality metrics like Jacobian, skew, warpage etc. If it does not take it, make it into a solid body like a .iges, solidpart, etc. then bring it in. I would mesh with solid elements, using a tet4 to get it to work, then remesh to a tet10 for accuracy. I have linked a enterfea blog post that might be handy and there are likely many more. These are an easy read with lots of pictures and little jargon to help you understand some of these topics. If you are brand new to FE, this is a difficult problem to start with so dont get discouraged. Feel free to ask more questions below. Good Luck!

Hey guys, I have some meshing problems with volume tetra and hope you guys can give me some tips. 1. Lines on geometry surface. For example, I converted an STL file (surface geometry defined by triangules) into a STEP file (solid body) and the triangular grids stay on the solid body surface. If I don't toggle (Geometry - quick edit - toggle edge) those surface lines, the 3D mesh (volume tetra) or 2D surface mesh (2D automesh) are gonna follow those surface lines. If I toggle those surface lines, volume tetra or 2D automesh won't be able to recognize the surface boundary of the geometry. I have an example geometry attached here, "file 1 - coccygeus left". Let me know how would you deal with the surface lines if you don't want your mesh to follow those lines. 2. Geometry defects. Still, STEP file converted from STL file. Sometimes there are defects in the CAD model like the surface lines are messed up, as shown in the figure below. Volume tetra won't work properly. I cannot do 2D automesh either. I attached the STEP file here, "file 2 - pubococcygeus". How would you mesh this file? Would you clean up the geometry first? 3. volume tetra does not work Still, STEP file coverted from STL file. I see no obvious messed up surface lines, but still, the volume tetra or 2D automesh won't work. I attached a file here, "file 3 - obturator". Please let me know how would you mesh this solid body. Thank you!