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<p>Hi Everyone</p><p>I created a dome composed of many beams as shown in the figure 1 and 2, and made a cylinder imapct it. I applied *CONTACT_AUTOMATIC_BEAMS_TO_SURFACE_ID between the cylinder and each beam. As for beams, there is a little difference in height between 2 beams. I didn't add any contacts. I added *CONSTRAINED_GENERALIZED_WELD_SPOT or *CONSTRAINED_SPOTWELD between the nodes of 2 beams closest to the intersection. After I ran the simulation, the cylinder went through the dome rather than impacting it, as shown in figure 3. The beams appeared to have a little oscillation. It seems that there is still some interaction force between the beam and the cylinder. But the cylinder just directly went through the beams. Does anybody know the reason and how to fix it? </p><p>I attached my .k file : https://tuprd-my.sharepoint.com/:u:/g/personal/tut06916_temple_edu/IQAtEDBPZhKLRYw4Kr0EEa_AAeYXal-n6FkEF1ROSpG_67k?e=86nLOW</p><p></p><p></p><p></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>Hi Everyone</p><p>I created a dome composed of many beams as shown in the figure 1 and 2, and made a cylinder imapct it. I applied *CONTACT_AUTOMATIC_BEAMS_TO_SURFACE_ID between the cylinder and each beam. As for beams, there is a little difference in height between 2 beams. I didn't add any contacts. I added *CONSTRAINED_GENERALIZED_WELD_SPOT or *CONSTRAINED_SPOTWELD between the nodes of 2 beams closest to the intersection. After I ran the simulation, the cylinder went through the dome rather than impacting it, as shown in figure 3. The beams appeared to have a little oscillation. It seems that there is still some interaction force between the beam and the cylinder. But the cylinder just directly went through the beams. Does anybody know the reason and how to fix it? </p><p>I attached my .k file : https://tuprd-my.sharepoint.com/:u:/g/personal/tut06916_temple_edu/IQAtEDBPZhKLRYw4Kr0EEa_AAeYXal-n6FkEF1ROSpG_67k?e=86nLOW</p><p></p><p></p><p></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>
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