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Hi @lsdynastudent, I know learning LS-Dyna is tough, especially when you are working with explosions (which I am not familiar with.) But I would suggest that you try to look at the energy plots of your simulation to see if anything is happening. You should see some energy spikes if your explosion happened and is just too small. You may need to re-run your simulation if you did not setup your *Database_options for GLSTAT, which is the global statistics and will allow you to look at the overall energy of your simulation. You will need to add this to your code and change the DT bolded value to be whatever time interval you want to look at your energies. So if if is a 10 ms simulation, make this lower than 0.1 ms. *DATABASE_RCFORC$# DT BINARY LCUR IOOPT0.1, 3, 0, 1 More details about database ascii options are below: If there is a little energy at least, then I would definitely double check that you units in your model match up. Let me know how it goes!

Hi @arun9660, The static and dynamic friction coefficients define how easily (or difficult) the slave and master side of the contact slide across one another. Just like real-life friction coefficients. For example, if you had a contact defined between a metal part and a glass part you could lookup "friction coefficient between metal and glass." You would probably stumble upon this website or something similar: And glass to metal would have a friction coefficient between 0.5 to 0.7 if dry or 0.2 to 0.3 if lubricated.

@mohammad_basri If you are getting an error in the middle of your simulation, it could be an issue with the material model or the contacts. Are there any contacts in this simulation? If so, that could definitely be the cause. This link may be helpful From my experience, implicit simulations require more than just baseline contact settings so you are probably going to need to activate the options ABC in the contact in LS-Prepost (below) and set IGAP to 1. IGAP has a huge effect on implicit contact stability. < span style="color: #666;"> Attachment :  igap_contact.JPG

Hi @mohammad_basri, To start, Implicit is much more sensitive than explicit so the debugging process can be a long, drawn out process. If you are doing a simple simulation that is in the range of seconds, consider an explicit simulation. If it's longer than that, then yeah, you will have to use Implicit. Is the issue happening immediately or a little while into the simulation? The link below has a lot of great tips for both debugging errors and improving implicit simulation performance. I would start with the control settings on slide 14 and go from there. Let me know if you have any specific questions regarding this.

Hi All, I am currently using the LOAD_BODY_Z card to apply gravity to my model (three parts), the first being SPH particles and the last two being Shells with MAT_RIGID properties. It appears that gravity seems to be acting in the correct direction for the SPH particles but not one of the shell parts (blue part seen at link below). Some model parameters set: *DEFINE_CURVE A1 O1 0.0 0.0 0.05 9.81 1000.0 9.81 *LOAD_BODY_Z --> uses the defined curve above. Does anyone have any ideas why one of shells appears to float up while the SPH particles are acting as expected for a gravity load? Cheers!

@nitin_kumar So to answer your first questions: 1.) When you say "fabric" do you mean that you are using *Mat_Fabric? Because if so then you can use Belytschko-Tsay. It is the default and I normally start here and change if I run into issues. If you are using a material that is not *Mat_Fabric but you still want a fabric-like response, then you can try Belytschko-Tsay membrane. This will make reduce bending stiffness so that the part behaves like a fabric. 2.) You say 8-node hexahedrals but the picture you attached is tetrahedral elements which are defined with 4 nodes, so I'm confused here. Your tetrahedrals should not be defined with 8 nodes. I think the issue is that you saved your mesh out with the option of "ten nodes format" so it filled nodes 5,6,7,8 with the same id as node 4. I never use the ten nodes format so I would just re-save your model with that option un-checked. I may have to get back to you on how to convert this but it should still work fine as you currently have it if you want to proceed with your project.

For any students interested in developing skills for finite element analysis / computer aided engineering (CAE), Altair provides an entire suite of software available for free for students. This is a great resource that every prospective student should take advantage of. You get access to Pre/Post-processors like Hypermesh, Analysis solvers (Expicit analysis: Radioss, Linear/nonlinear: Optistruct, Multi-body: MotionSolve ect.), Optimization software, and CAD. The link is below: I'm only familiar with Hypermesh and Hyperview so I won't be much help answering questions for any other software. But I am interested in learning more about them so hopefully we can all learn together.

Ah, yeah PrePost isn't really know for it's meshing capabilities and there's not much documentation for it. Wow sorry to hear that you had to create an entire python script for that, but awesome that you'd be willing to share with others in a similar predicament! This may be a little late, but Altair offers a free student version of hyperworks including hypermesh. It has restrictions on the number of nodes that you are able to use but it still may be worth looking into for smaller projects in the future: Let me know if you need any help with setting up your simulations.

As it says, DTO is a defined initial timestep. If you are not familiar with the concept of timesteps I suggest you read about it: The timestep in a simple sense, is determined by the minimum edge length of an element and the material of that element (Most influentially the mass). The smaller the timestep, the longer your model will take to run. If you manually define a timestep in LS-Dyna, then the mass of that element will be artificially increased during the simulation to achieve that timestep. This is what is called mass added during a simulation and can be found in the d3hsp or the message file of a simulation. Generally, you want to keep the mass added to less than 5% of the initial model mass (the compressed object, not the impactor). So I would look in your message file from the explicit simulation that you ran with the square tube to find what the calculated timestep was and define DTO as that times 1.05 and see how that works for you.

Hi, I'd like some advice regarding applying initial velocities to the LSTC rigid body models ( Usually, I'd just use *INITIAL_VELOCITY_GENERATION and assign an initial velocity to a group of deformable parts in a part set. However, in this model, there are many rigid bodies, discrete elements and joints. How would you go about adding an initial velocity to the whole dummy? I'd like to do a simple test where I add an initial velocity and have the dummy impact a stationary object, like a block or a cylinder. I know the alternative would be give the block an initial velocity, but I'm curios to see the body kinematics after the collision. Attachment : image.png Thanks! Attachment : LSTC.H3_50TH_STANDING.100630_BETA.k