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<p>Hello,</p><p>I would like to simulate the process of sheet metal stamping and then springback. In both processes, I would like to take into account the Bausinger effect, anisotropy , softening and workhardening stagnation stress reversals, and strain rate . The Yoshida Uemori model + Anisotropic model, e.g., Yld2000 + strain rate, would be suitable for this task. The problem is that LS Dyna does not have such a model . Therefore, I would like to ask if in the first simulation, i.e., the sheet metal forming simulation, I could use the mat_133 model, then transfer the simulation results to a new springback simulation and change the material model to mat_242, and then run a new springback simulation with the mat_242 material model? The mat_133 model has a backstress historyhttps://lsdyna.ansys.com/history-variables/</p><p> </p><p> </p>
<p class="ds-markdown-paragraph">Hello everyone,</p><p class="ds-markdown-paragraph">I am encountering an issue with tied contacts during a total restart analysis for springback calculation and would appreciate some advice. （1）First analysis A steel formwork falls onto the rock，used shell element： and used TIED_SHELL_EDGE_TO_SURFACE_BEAM_OFFSET and TIED_SHELL_EDGE_TO_SURFACE_BEAM_OFFSET：<br> calculation in this step is normal，and tied contact works fine： （2）total start used CONTROL_DYNAMIC_RELAXATION keyword to calculate the springback but all tied contact was failed：<br> we could see that penetration occurred between the parts. Has anyone encountered a similar issue? Any suggestions on what parameters I should check or adjust would be greatly appreciated.</p>
<p>Hello,</p><p>I requested the usermat version of LS-DYNA from my institution's software office, from the link found in here: https://ftp.lstc.com/anonymous/outgoing/support/FAQ/user_defined_materials.faq. However, after receiving the files, the file types were unexpected, and different from what the previous posts and user manual has mentioned. </p><p>They provided me with a folder named "ls-dyna....mpi" and inside were only a license folder, and 3 executable files named l2a, lstc_client, and ls-dyna...mpi. Are these the files I should be expecting, and if so, how do I use them?</p><p>Thanks </p>
<p>Hello,</p><p>I'm creating a few tests of FSI analysis with ALE formulation but I can't get in the post processing the local stresses of the shell impacting in water.</p><p>I've definied d3plot, FSI, intfor and other output but I get just the water pressure and not the one in the shell element</p>
<p>I have seen examples that use *CONTROL_TIMESTEP to set the length of each step in the mechanical solver of the simulation. There is also *EM_CONTROL_TIMESTEP, which sets the time of each magnetic step. Do these magnetic steps fit within the mechanical steps, or are they run in parallel?</p><p dir="auto">*EM_CONTROL has ncylfem and ncylbem, which it defines as number of magnetic cycles before recalculating fem and bem matricies. By increasing this value, do you decrease the frequency at which fem/bem matricies are rebuilt, also decreasing the simulation time.</p><p dir="auto">*EM_CONTROL_MAGNET uses ncycm to recalculate the magnetic vectors after a certain number of EM cycles. This should follow the same logic, where increasing the value would decrease because the magnetic vectors are recalculated less frequently. </p><p dir="auto"> </p><p dir="auto">In a simplified example, lets say *CONTROL_TIMESTEP is set to 1 second. So each step of the simulation is 1 second. If *EM_CONTROL_TIMESTEP is set to 0.25 seconds, there would be four EM cycles per mechanical step. If the ncycfem/bem are set to 2, fem/bem matricies would be recalculated every 2 magnetic cycles, or 0.5 seconds/ every 0.5 mechanical steps. With *EM_CONTROL_MAGNET setting ncycm to 4, the magnetic vectors would be recalculated every 4 EM cycles or every second/ every mechanical step. Is this a correct intrepertation of how the keywords define properties?</p>
<p>I understand LS Dyna is "unitless" where everything is built off of relative scaling. If my mesh sizing is in mm, mass units are input in grams, I should be working with pascals and uN. What I was wondering, is how to scale the magnetic units to fit this. As many magnetic units are based off of Amps, which don't necessarily have a relation to mm, grams, or seconds. </p><p>From what I understand, EM keywords (or at least *EM_EXTERNAL_FIELD) use B field in Tesla. Which can be written as N/(Am). To scale that for a mm/g/uN system, it means that a numerical value put in would be on the scale of mTesla, right?</p><p>*EM_PERMANENT_MAGNET specifically mentions Hc being written in A/m (pg 488 in the Em manual https://lsdyna.ansys.com/wp-content/uploads/2025/04/LS-DYNA_Manual_Vol_III_R16.pdf), for my unit system that should be scaled to A/mm. Or am I reading the manual wrong; where remark 1 is simply telling me how I should scale a given A/m value to B field values, and like the rest of the EM keywords, all values should be written as a B field in some scale of Tesla.</p>
<p>I am trying to simulate the penetration of the bullet on the concrete target. In my silumation result, what I observe is that the deceleration peak magnitude is dependent on the velocity of the impactor, however the experimental result that I am trying to simulate shows that the peak deceleration magnitude is independent of the velocity , rather it depends on the compressive strength . How should I incorporate this velocity independent criteria in my LS DYNA simulation.</p>
<p> </p><p>Hello,</p><p>I'm trying to create a FSI model to simulate an impacto of a shell element on the water using the S-ALE formulation.</p><p>I've definied all the keywords necessary for the model but running the analysis i get this error.</p><p>I've used shell elements with elastic material and mat null for the water</p><p> </p><p></p>
<p>I'm trying to simulate the final bending angle of a soft finger at -70 kPa using LS-DYNA.</p><p>However, the simulation results are consistently much smaller than the actual angle.</p><p>I can't figure out why the difference is so large.</p><p>Could someone please help me identify the problem?</p><p>Below are my simulation settings and screenshots from ANSYS.</p>
<p>Hello,</p><p>I would like to simulate the process of sheet metal stamping and then springback. In both processes, I would like to take into account the Bausinger effect, anisotropy , softening and workhardening stagnation stress reversals, and strain rate . The Yoshida Uemori model + Anisotropic model, e.g., Yld2000 + strain rate, would be suitable for this task. The problem is that LS Dyna does not have such a model . Therefore, I would like to ask if in the first simulation, i.e., the sheet metal forming simulation, I could use the mat_133 model, then transfer the simulation results to a new springback simulation and change the material model to mat_242, and then run a new springback simulation with the mat_242 material model? The mat_133 model has a backstress historyhttps://lsdyna.ansys.com/history-variables/</p><p> </p><p> </p>
<p class="ds-markdown-paragraph">Hello everyone,</p><p class="ds-markdown-paragraph">I am encountering an issue with tied contacts during a total restart analysis for springback calculation and would appreciate some advice. （1）First analysis A steel formwork falls onto the rock，used shell element： and used TIED_SHELL_EDGE_TO_SURFACE_BEAM_OFFSET and TIED_SHELL_EDGE_TO_SURFACE_BEAM_OFFSET：<br> calculation in this step is normal，and tied contact works fine： （2）total start used CONTROL_DYNAMIC_RELAXATION keyword to calculate the springback but all tied contact was failed：<br> we could see that penetration occurred between the parts. Has anyone encountered a similar issue? Any suggestions on what parameters I should check or adjust would be greatly appreciated.</p>
<p>Hello,</p><p>I requested the usermat version of LS-DYNA from my institution's software office, from the link found in here: https://ftp.lstc.com/anonymous/outgoing/support/FAQ/user_defined_materials.faq. However, after receiving the files, the file types were unexpected, and different from what the previous posts and user manual has mentioned. </p><p>They provided me with a folder named "ls-dyna....mpi" and inside were only a license folder, and 3 executable files named l2a, lstc_client, and ls-dyna...mpi. Are these the files I should be expecting, and if so, how do I use them?</p><p>Thanks </p>
<p>Hello,</p><p>I'm creating a few tests of FSI analysis with ALE formulation but I can't get in the post processing the local stresses of the shell impacting in water.</p><p>I've definied d3plot, FSI, intfor and other output but I get just the water pressure and not the one in the shell element</p>
<p>I have seen examples that use *CONTROL_TIMESTEP to set the length of each step in the mechanical solver of the simulation. There is also *EM_CONTROL_TIMESTEP, which sets the time of each magnetic step. Do these magnetic steps fit within the mechanical steps, or are they run in parallel?</p><p dir="auto">*EM_CONTROL has ncylfem and ncylbem, which it defines as number of magnetic cycles before recalculating fem and bem matricies. By increasing this value, do you decrease the frequency at which fem/bem matricies are rebuilt, also decreasing the simulation time.</p><p dir="auto">*EM_CONTROL_MAGNET uses ncycm to recalculate the magnetic vectors after a certain number of EM cycles. This should follow the same logic, where increasing the value would decrease because the magnetic vectors are recalculated less frequently. </p><p dir="auto"> </p><p dir="auto">In a simplified example, lets say *CONTROL_TIMESTEP is set to 1 second. So each step of the simulation is 1 second. If *EM_CONTROL_TIMESTEP is set to 0.25 seconds, there would be four EM cycles per mechanical step. If the ncycfem/bem are set to 2, fem/bem matricies would be recalculated every 2 magnetic cycles, or 0.5 seconds/ every 0.5 mechanical steps. With *EM_CONTROL_MAGNET setting ncycm to 4, the magnetic vectors would be recalculated every 4 EM cycles or every second/ every mechanical step. Is this a correct intrepertation of how the keywords define properties?</p>
<p>I understand LS Dyna is "unitless" where everything is built off of relative scaling. If my mesh sizing is in mm, mass units are input in grams, I should be working with pascals and uN. What I was wondering, is how to scale the magnetic units to fit this. As many magnetic units are based off of Amps, which don't necessarily have a relation to mm, grams, or seconds. </p><p>From what I understand, EM keywords (or at least *EM_EXTERNAL_FIELD) use B field in Tesla. Which can be written as N/(Am). To scale that for a mm/g/uN system, it means that a numerical value put in would be on the scale of mTesla, right?</p><p>*EM_PERMANENT_MAGNET specifically mentions Hc being written in A/m (pg 488 in the Em manual https://lsdyna.ansys.com/wp-content/uploads/2025/04/LS-DYNA_Manual_Vol_III_R16.pdf), for my unit system that should be scaled to A/mm. Or am I reading the manual wrong; where remark 1 is simply telling me how I should scale a given A/m value to B field values, and like the rest of the EM keywords, all values should be written as a B field in some scale of Tesla.</p>
<p>I am trying to simulate the penetration of the bullet on the concrete target. In my silumation result, what I observe is that the deceleration peak magnitude is dependent on the velocity of the impactor, however the experimental result that I am trying to simulate shows that the peak deceleration magnitude is independent of the velocity , rather it depends on the compressive strength . How should I incorporate this velocity independent criteria in my LS DYNA simulation.</p>
<p> </p><p>Hello,</p><p>I'm trying to create a FSI model to simulate an impacto of a shell element on the water using the S-ALE formulation.</p><p>I've definied all the keywords necessary for the model but running the analysis i get this error.</p><p>I've used shell elements with elastic material and mat null for the water</p><p> </p><p></p>
<p>I'm trying to simulate the final bending angle of a soft finger at -70 kPa using LS-DYNA.</p><p>However, the simulation results are consistently much smaller than the actual angle.</p><p>I can't figure out why the difference is so large.</p><p>Could someone please help me identify the problem?</p><p>Below are my simulation settings and screenshots from ANSYS.</p>
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