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<div class="text-neutral-content"><div class="mb-sm mb-xs px-md xs:px-0 overflow-hidden" data-post-click-location="text-body"><div id="t3_1rr5r9z-post-rtjson-content" class="md text-14-scalable pb-2xs [--emote-size:20px]" dir="auto"><p>Hi,</p><p>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.</p><p>Initial Attempt & Issue:</p><p>I first tried the implicit thermal solver using:</p><p>- *CONTROL_SOLUTION (Thermal-Structural Analysis)</p><p>- *CONTROL_THERMAL_NONLINEAR</p><p>- *CONTROL_THERMAL_SOLVER</p><p>- *CONTROL_THERMAL_TIMESTEP</p><p>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.</p><p>Current Error:</p><p></p><p>forrtl: severe (164): Program Exception - integer divide by zero</p><p>Image PC Routine Line Source</p><p>lsdyna_mpp_dp_imp 00007FF731E6B4CC XPLCTH_INIT 1148 dyn20x.F</p><p>...</p><p></p><p>The crash occurs during initialization (XPLCTH_INIT), suggesting a division by zero in the thermal data setup.</p><p>Specific Questions:</p><p>Explicit Thermal Setup with S-ALE:</p><p>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.</p><p>- How do I properly define SETID for S-ALE domains in these cards? Should I use *SET_MULTI_MATERIAL_GROUP instead?</p><p>Phase Change Modeling:</p><p>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?</p><p>Divide-by-Zero Cause:</p><p>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?</p><p>Model Context:</p><p>- 2D Axisymmetric S-ALE mesh (fine resolution)</p><p>- 3 ALE Multi-Material Groups: HSLA-100 Steel, Tungsten Carbide, Vacuum</p><p>- Thermal properties defined via *MAT_THERMAL_ISOTROPIC and *MAT_THERMAL_ISOTROPIC_PHASE_CHANGE</p><p>- Using MPP R14.1.1 on Windows</p><p>Keyword file attached for reference:</p><p><a class="relative pointer-events-auto a cursor-pointer
underline" href="https://buffalo.box.com/s/y7rz3bqg4xsvuir6z94b50mcg2g3jp1s" target="_blank" rel="noopener">https://buffalo.box.com/s/y7rz3bqg4xsvuir6z94b50mcg2g3jp1s</p><p>Any guidance on proper explicit thermal initialization with S-ALE and phase change setup would be greatly appreciated.</p><p>Thanks,</p><p>Amrith</p></div></div></div><div> </div>
<p>Hi all, I'm trying to learn simulating hypervelocity impact by myself, I notice that most of the journal papers choose Autodyn. And my question is what's diference between using Autodyn standalone and using Ansys/ explicit dynamics plus Autosdyn? Also, which way is easier to model layered composite material? </p>
<p></p><p>I got these error codes while trying to run an FEA simulation, and I have tried to go back in and define the section IDs, but it isn't working. Does anyone have advice to fix these?</p>
<p>Hi All, </p><p>I created 2 beams. After I applied cross section, there was an overlap between the two beams. I applied *contact_automatic_general between 2 beams. I found the beam would repel each other because there is model overlap. Does anybody know how to get rid of the repulsive force, even though there is overlap?</p><p></p><p></p><p></p><p></p>
<p>Hi all,</p><p>I am trying to simulate a hypervelocity impact (~5 km/s) on a CFRP laminate consisting of 16 plies with 15 resin-rich interlayers using the SPH method.</p><p>I already know the stacking sequence and fiber orientation of each ply. However, I am unsure how to properly construct the laminated structure in an SPH model.</p><p>In particular, I would like to understand:</p><p>• How to assign the orthotropic fiber orientation for each ply when using SPH particles.<br>• How to represent the interlaminar interfaces between plies (e.g., contact or cohesive behavior).<br>• How to build the layered laminate structure itself so that ply-level damage mechanisms such as fiber breakage, fiber–matrix debonding, and ply delamination can be captured.</p><p>What is the recommended approach to model the ply orientations, interply interfaces, and the laminate stacking structure when using SPH for CFRP impact simulations?</p>
<p>Hello everyone</p><p>I'm working on a ballistic analysis on Ls-Dyna. Before I do my own simulations I'm trying to replicate an article right now. In that article a rigid ball smashes into a aluminum armor plate. Material model for aluminum is Johnson Cook and the values of it were given in article but when I run the simulation stress values looks weird. For instance X,Y and Z stress values all looks the same, there is NO shear stress whatsoever, there are only small dots of stress in von mises and tresca stress, effective plastic strain is non-existant and the bulge that appears when the ball penetrates through the armor seems too big. What could be causes of this? When I use simplified johnson cook model stress and strain values looks fine but when I switch to normal johnson cook everything looks wrong. Can somebody help please??? Pictures of my problem are in the link: https://imgur.com/a/nTRUaSL</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>
<div class="text-neutral-content"><div class="mb-sm mb-xs px-md xs:px-0 overflow-hidden" data-post-click-location="text-body"><div id="t3_1rr5r9z-post-rtjson-content" class="md text-14-scalable pb-2xs [--emote-size:20px]" dir="auto"><p>Hi,</p><p>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.</p><p>Initial Attempt & Issue:</p><p>I first tried the implicit thermal solver using:</p><p>- *CONTROL_SOLUTION (Thermal-Structural Analysis)</p><p>- *CONTROL_THERMAL_NONLINEAR</p><p>- *CONTROL_THERMAL_SOLVER</p><p>- *CONTROL_THERMAL_TIMESTEP</p><p>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.</p><p>Current Error:</p><p></p><p>forrtl: severe (164): Program Exception - integer divide by zero</p><p>Image PC Routine Line Source</p><p>lsdyna_mpp_dp_imp 00007FF731E6B4CC XPLCTH_INIT 1148 dyn20x.F</p><p>...</p><p></p><p>The crash occurs during initialization (XPLCTH_INIT), suggesting a division by zero in the thermal data setup.</p><p>Specific Questions:</p><p>Explicit Thermal Setup with S-ALE:</p><p>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.</p><p>- How do I properly define SETID for S-ALE domains in these cards? Should I use *SET_MULTI_MATERIAL_GROUP instead?</p><p>Phase Change Modeling:</p><p>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?</p><p>Divide-by-Zero Cause:</p><p>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?</p><p>Model Context:</p><p>- 2D Axisymmetric S-ALE mesh (fine resolution)</p><p>- 3 ALE Multi-Material Groups: HSLA-100 Steel, Tungsten Carbide, Vacuum</p><p>- Thermal properties defined via *MAT_THERMAL_ISOTROPIC and *MAT_THERMAL_ISOTROPIC_PHASE_CHANGE</p><p>- Using MPP R14.1.1 on Windows</p><p>Keyword file attached for reference:</p><p><a class="relative pointer-events-auto a cursor-pointer
underline" href="https://buffalo.box.com/s/y7rz3bqg4xsvuir6z94b50mcg2g3jp1s" target="_blank" rel="noopener">https://buffalo.box.com/s/y7rz3bqg4xsvuir6z94b50mcg2g3jp1s</p><p>Any guidance on proper explicit thermal initialization with S-ALE and phase change setup would be greatly appreciated.</p><p>Thanks,</p><p>Amrith</p></div></div></div><div> </div>
<p>Hi all, I'm trying to learn simulating hypervelocity impact by myself, I notice that most of the journal papers choose Autodyn. And my question is what's diference between using Autodyn standalone and using Ansys/ explicit dynamics plus Autosdyn? Also, which way is easier to model layered composite material? </p>
<p></p><p>I got these error codes while trying to run an FEA simulation, and I have tried to go back in and define the section IDs, but it isn't working. Does anyone have advice to fix these?</p>
<p>Hi All, </p><p>I created 2 beams. After I applied cross section, there was an overlap between the two beams. I applied *contact_automatic_general between 2 beams. I found the beam would repel each other because there is model overlap. Does anybody know how to get rid of the repulsive force, even though there is overlap?</p><p></p><p></p><p></p><p></p>
<p>Hi all,</p><p>I am trying to simulate a hypervelocity impact (~5 km/s) on a CFRP laminate consisting of 16 plies with 15 resin-rich interlayers using the SPH method.</p><p>I already know the stacking sequence and fiber orientation of each ply. However, I am unsure how to properly construct the laminated structure in an SPH model.</p><p>In particular, I would like to understand:</p><p>• How to assign the orthotropic fiber orientation for each ply when using SPH particles.<br>• How to represent the interlaminar interfaces between plies (e.g., contact or cohesive behavior).<br>• How to build the layered laminate structure itself so that ply-level damage mechanisms such as fiber breakage, fiber–matrix debonding, and ply delamination can be captured.</p><p>What is the recommended approach to model the ply orientations, interply interfaces, and the laminate stacking structure when using SPH for CFRP impact simulations?</p>
<p>Hello everyone</p><p>I'm working on a ballistic analysis on Ls-Dyna. Before I do my own simulations I'm trying to replicate an article right now. In that article a rigid ball smashes into a aluminum armor plate. Material model for aluminum is Johnson Cook and the values of it were given in article but when I run the simulation stress values looks weird. For instance X,Y and Z stress values all looks the same, there is NO shear stress whatsoever, there are only small dots of stress in von mises and tresca stress, effective plastic strain is non-existant and the bulge that appears when the ball penetrates through the armor seems too big. What could be causes of this? When I use simplified johnson cook model stress and strain values looks fine but when I switch to normal johnson cook everything looks wrong. Can somebody help please??? Pictures of my problem are in the link: https://imgur.com/a/nTRUaSL</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>
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