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Hi I performed an explicit analysis where an object (elastic wood) hits a tank steel shell with 3 m/s. After t = 0.04 sec, this is the energy plot I got. My question is whether this energy plot seems okay. One of my colleagues said that kinetic and internal energy plots tell us about explicit analysis whether it is successful or not. 

I'm trying to simulate a bone block being cut by a burr. I want to use an ALE method to simulate this. Currently I'm running into issues when setting up the connections tab of the simulation because in the frictional contact the selections for target and body stay yellowed out. I'll attach screenshots of the contact and geometry definitions. I added a coupling between the two but I don't know what that does or if it helps.

I'm trying to use the SPH method to simulate a burr cutting bone-block. I want to capture a 50 ms ramp time of the burr. The main issue I'm seeing is that the burr is just disappearing from the simulations after 4.997e-2. I'm new to Ansys and don't know what could have caused this. Any help would be much appreciated. 

I am working on electromagnetic railgun launching, and my LS-DYNA simulation produces negative volumes as soon as the current is applied. Why is this happening?

I have set up a FSI simulation using the S-ALE keywords. I am replicating the method used in the following paper to find the added mass of a floating body.https://doi.org/10.1016/j.marstruc.2016.05.005With a coarse mesh of 1m size for the ALE elements, the simulation runs fine with the timesteps remaining almost consistent throughout the entire simulation.But when the S-ALE mesh is made with progressive spacing, such that at the free surface of air and water, the element size reduces to 0.4m, the timesteps drop from the initial calculated timestep. How to identify the cause of this problem and resolve it to have a consistent timestep throughout the simulation?I am currently using the default settings PFAC=0.1 for the coupling.

As recommended in the S-ALE tutorials, I would like to set up the Fluid-Structure interaction using the *ALE_STRUCTURED_FSI keyword, with a load curve defined for the penalty coupling pressure.1.Is there any way to roughly estimate the coupling pressure? 2.As recommended in the guidelines, I have tried to set the curves by defining two points, one at origin and the other with (absicca = 1/10 ALE element size, ordinate = Pmax). Does this coupling pressure refer to the total pressure at the fluid-structure interface or does it only refer to the additional pressure due to the coupling?When we have a submerged structure with a large draft, the hydrostatic pressure in the ALE domain will contribute significantly to the total pressure. So does this Pmax on the load curve have to include the hydrostatic pressure?3.Since leakage control is automated in the new S_ALE FSI keyword, how to identify in a simulation if the set coupling pressure (from the load curve) is adequate or if the automated leakage control is getting activated?

Hi,I'm curious about how the proximity selection tool criteria is defaultly defined. I've been searching for information on this matter but haven't been able to find any. For instance, in my model, it's automatically set to 2.47885 mm.I imagine it has something to do with the average element size in my model... Thanks

Dear community,I try to set up a full Ls-Dyna restart in workbench.Furthermore, I want to activate/deactivate parts for this restart.I tried the following keyword snippet to delete parts:$   Keyword Snippet$   Do not leave any unintentional empty lines in this editor*DELETE_PART60910, 60912, 21573, 21571, 21941*ENDUnfortunately that did not work.I also tried construction stages:*DEFINE_STAGED_CONSTRUCTION_PART60910, 0, 1*DEFINE_STAGED_CONSTRUCTION_PART60912, 0, 1*DEFINE_STAGED_CONSTRUCTION_PART21573, 0, 1*DEFINE_STAGED_CONSTRUCTION_PART21571, 0, 1$PARTID: 60910, 60912, 21573, 21571*DEFINE_CONSTRUCTION_STAGES0, 0.0, 0.5, 0.0, 0.0, 0.5*DEFINE_CONSTRUCTION_STAGES1, 0.5, 0.55, 0.0, 0.5, 0.55*ENDThat did not work either.However, I did not get any errors in the solver output.I look very forward to your suggestions.

If you use the spg unit to initialize the confining pressure loading stress and set the spg unit bond base to break, will there be stress fluctuations in the remaining units after the bond base breaks?

I've recently been attempting to insert my code into an existing EXEDIT subroutine in Autodyn, aiming to achieve temperature transfer functionality within a 2D multi-material Eulerian domain. However, upon execution, it seems that my code isn't producing any noticeable effects. Below is the portion of code I've inserted into the existing EXEDIT subroutine:I would like to know if this functionality can be implemented through a user subroutine, whether it should be written in an EXEDIT subroutine, and how to modify model parameters during the calculation process and return them to the main program to continue the calculation.Version: ANSYS 15.0; VS 2010; Fortran 2011Operating System: Windows 10 ProfessionalThank you to everyone who can provide assistance. I truly appreciate your support and guidance!

As part of my project I had performed an analysis of a circular fabric plate. I had conducted the analysis by providing horizontal, vertical and cross slits at the centre of the plate with varying geometry. So when I checked the results, as the width of slit increases the stress is reduced for the horizontal and vertical slits and in case of cross slits initially the stress increases with increase in slit size, then stress decreases with increase in slit size. Why does it happen like this?Also, instead of slit when providing hole in the centre with varying diameter, the stress value shows initial increase in stress with decrease in hole dia and changes the pattern for small diameter. What could be the reason for this?

Hello all,I am running a simulation using LS-Dyna with *LOAD_NODE_SET and constraining some DOF at distinct ends with *BOUNDARY_SPC_SET. Following some recommendations given on previous posts, I am using a ramp to define the curve and then use a constant value (see graph below). To check the quasi-static condition, I am using glstat and matsum to verify that the kinetic energy is below 5% of the internal energy; this is true for glstat and for matsum only one part had high kinetic energy.My question comes from checking some variables (see graph below for v-m stress of just 2 elements, whole part rigid-body motion) for which I observe this weird oscillating behavior that prevents me to obtain confident results at the end of the simulation; naturally I am expecting a line that shows results converging to a value (similar to my loading curve). Has anyone experience a similar issue like this? Is this caused by the ramp application curve... maybe it's too fast? Or maybe it's a lack of boundary conditions? Any idea would be greatly appreciated.Also a follow up question. I noted there's an option for rigid-body acceleration in the history variable option: I have nonzero (still relatively small considering my time units) values for some parts. Is zero acceleration also a condition for quasi-static behavior or is the internal vs kinetic energy ratio sufficient?   

Hello,I want to model a semi infinite fluid domain using ambient elements in SALE mesh. I have created a solid set using SET_SOLID_GENERAL and the mesh control points required. While defining the *BOUNDARY_AMBIENT keyword, is it mandatory to input the Load curves for Internal energy and Volume fraction? When the pressure inflow/outflow in the ambient boundaries are unknown, can the LCIDs for internal energy and volume fraction be left blank? 

Hello, I'd like to ask some questions related to the AUTODYN energy deposition subroutine EXSIE. I have a two-dimensional copper target with grids of 500 and 100 in the I and J directions, respectively. The energy deposition of each grid is different and is entered by reading a text file.As shown in the picture of my subroutine code, my idea is to call this subroutine once in each loop, and then enter the energy deposition corresponding to I and J, but in fact, this is not the case. Can you help me to see what's wrong?What I want to calculate is to import it into each grid of the copper target through external energy deposition, and then calculate the changes in density, pressure, temperature and so on over a certain period of time. And then I have another question that I want to know is that when I look at the cloud map of the calculation, the temperature is always zero and there is no change.The picture shows the external energy deposition that I want to import. The first and second columns are XBI y coordinates, and the third is energy deposition.

Good Afternoon,I am currently working in LS-PrePost and I am trying to create a pulsatile, sinusoidal inlet velocity for a 2D geometry simulation. The inlet velocity expression is 0.0266*0.00786*sin(2*3.14*0.3*TIME). For the inlet velocity, I have inserted via the keyword *DEFINE_CURVE_FUNCTION as shown in the image, however I am receiving an error.What are the steps to correcly apply this pulsatile sinusoidal function to the inlet?

Hello. I am simulating the bending process of a thin plate.I would like to measure stain and stress in a coordinate system along the material axis.Furthermore, my goal is to visualize them with "Fringe Component" and to output the values to a file.Please give me your ideas.Thanks.Chihiro Komatsu

Hi, I am modeling a 3D object that is part of a hollow sphere which radius is 7.8 mm and its thickness is 0.536mm. From the side view, it makes a circular arc equal to 120 degrees. It is made of a linear elastic material with E = 0.3 Mpa. At the top vertex, a chain of steel spheres sits on this object, and their displacement is limited to the Y axis. The bottom corner face of the object is fixed and a constant pressure of 2400pa is applied on the interior surface of the object.At first, I did a Static Structural analysis to find deformations related to gravity and the constant pressure, and then I wanted to do an explicit analysis for an impact through the chain using Ls Dyna for about 1 millisecond. Even though everything is the same for the Ls Dyna analysis, the curved object starts oscillating. I have used dynamic relaxation for Standard Earth Gravity and also option "Both" for Dynamic Relaxation Behavior of applying the pressure. So the oscillation amplitude is not too large according to the scale of the whole model. However, It is enlarging over time, and even this small oscillation will significantly affect my final results since I need high accuracy. Two attachments show the oscillation. The image below contains a graph showing deformation of the top vertex of the curved object. Why at the beginning of the Ls Dyna analysis, its deformation suddenly reduces from 0.0573mm (which is the result of the Static Structural analysis) to 0.055024mm and then gradually goes up again?To solve the oscillation issue, is it a good idea to use an Ls Dyna Restart analysis for the impact after the Ls Dyna analysis and reduce the first Ls Dyna analysis end time from 1 ms to 0.2 ms to have the minimum oscillation amplitude before the impact (This approach significantly increases the ansys file size and I don't know why!?)? If not, what should I do to completely dampen this oscillation?Also, I should mention that since I need to measure Nodal Contact Force through this analysis, my only option is to do a 3D analysis in Ls Dyna.

Is it possible for LS-DYNA version R14 itself to have some bugs? I run old files in newer version as I doubted this. For example, when MAT Erosion is used with Titles, and run in LS solver all the input values shift down one row and the material failure didn't occur. (I have to make the simulation without title)Another example is that SOLID SPG with IDAM 1 and FS 0.002 works in R11, but the same keyword file fails to show failure in R14.One more example is In tension failure analysis, element deletion didn't happen as it is supposed to. In the figure, the element at the tip has to be deleted first. (It works fine with older version.)

Can you please let me know if there is a way to export unit vectors along the eigen directions or scaled vectors representing the total principal stresses?  I also would like to know if there is a way to output eigen vectors of plastic strain rate.  We are using Mat-18, Johnson-Cook. The real goal is to create streamlines of these eigen vectors. We used to obtain them from ABAQUS/CAE and had to then sort neighboring vectors to make this meaningful.  However, looking at the vectors in LS-PREPOST they seem to already be sorted, at least in the region of most interest to use.  Is there a way in LS-PREPOST to directly create streamlines of these vector fields?  I ask because I am not familiar with the fluids post-processing and believe this should be easily doable. Or should we look into LS-Taurus (is it even available, or work?) or some other software? Thanks,Vis 

How can I define Failure such as Volumetric strain in SPH models. I am using LS duna

Hi everyone,I'm currently working on implementing an user defined EOS (Equation of State) using a lookup table similar to SESAME EOS in Autodyn. I've managed to modify the user-defined EOS in the mdeos_user_1.f90 file, but I'm unsure about how to include a table in the EOS. If anyone has any advice or suggestions, I would greatly appreciate your assistance.Thanks in advance!

Hi all, I am trying to model an iced, rectangular, metallic plate being hit from underneath with a cylindrical impactor. The plate is clamped on its short ends and modeled using *MAT_ELASTIC. To simulate cohesive fracture within the ice, I use peridynamics: the nodes of the block of ice are disconnected and the elements use *SECTION_SOLID_PERI and *MAT_ELASTIC_PERI. The block of ice is attached to the plate via a tiebreak contact. While the parameters in *MAT_ELASTIC_PERI are quite straightforward and the relationships to micro-modulus and critical stretch are well-defined, it is not the case with *SECTION_SOLID_PERI and the "Dr" parameter. The issue I am facing is that I am not sure which value to use for Dr, since changing it affects the results significantly. Moreover, I do not understand why, under the hood, LS-DYNA performs a check on the surrounding neighbors of every point to make sure there are at least 12 and at most 136, and then tunes the horizon size accordingly. Does that mean that the used horizon size is not the same as the one calculated using "Dr"?For reference, I am attaching a picture of the model (green part is ice, the other part is the plate, the impactor hits the plate on its center from the back), and two snapshots of two identical simulations at the same time after the impact, the only difference being the "Dr" parameter used. The first one has Dr=1, and the second one, Dr=2. The snapshots represent a top view of only the ice, where the effective plastic strain (ie peridynamics damage) is fringed. As shown, there is some difference to the crack patterns that emerge from the impact just by changing this parameter.I would appreciate any advice regarding how to pick this value or at least minimise its effect on the final results, as well as any improvements that could work in this case. Many thanks in advance!

Hello,I like Prepost but its repeated crashing when building a model is annoying (it becomes unresponsive which requires killing it to be more accurate).It mostly occurs when changing the nodes or elements (deleting, generating though elgen or remesh, replacing nodes, splitting, etc.) but never when changing coordinates (e.g. transforming). This happens with different models that open without warning in prepost (mostly R11 and R9).This has been happening for many years (I have been using prepost regularly but not full time for over 15 years).After the crash, repeating the same operation on a freshly opened file usually works. If not, doing the same operation in a different version works.So I typically save quite often a proj file as backup (quick to update) and restart from there after the crash.But today, my proj file got corrupted somehow as I was working in 4.12 2025/R1. I cannot open it anymore in any version and I just lost two hours of tedious work. This is a new one.I have automatic proj save (every 8 minutes) but I guess it does not keep the versions after the file is saved (why by the way?). Bummer.So, my questions are the following:any possibility to extract contents of a corrupted proj file ?any possibility to keep intermediate .proj files? (the software should check that the file is not corrupted before deleting by the way)any possibility to generate crash dumps that could then be used by developpers for debug (difficult to post a bug for something that does not happen on a freshly opened file)when it becomes unresponsive (e.g. on element delete), what happens internally? If updating the nodes/elements database, any function to check its consistency (to prevent crashing) ? How long to wait to see if it can recover (lets say for a model <50k elements on a modern PC)?any other suggestion on settings/practices? I alternate between Prepost 4.7, 4.8, 4.10, 4.11, 4.12 (each has its own lsppconf) including double precision versions on 4.11/4.12 (seems useful with models with large ids), on two windows 10 machines with 32GB memory or more (one with integrated graphics, one with a Nvidia GPU: no difference by the way)  and the current crashes are on a small model (<30k elements, <50 parts/mat/sections, a few contacts, spotwelds and CNRB options).ThanksPhilippe

Hello Forum,I am running a full SALE calculation, but would like to be able to just somehow get an ASCII output of the pressure history of the contacting element without needing to store large D3PLOTS and probe the element pressure. Is there an easier way to do this for ALE elements? I'm trying to use DATABASE_FSI_SENSOR, but I'm not sure how to set that up correctly... Thanks,Peter

Hello,I'm currently facing some difficulties in setting up the Analysis Settings for Explicit Dynamics. In particular, I'm having trouble with the Erosion Controls section, where the default value for Geometric Strain Limit is set to 1.5.However, while browsing through a post on the Ansys Learning Forum, I came across a suggestion stating that this value should be set as the ratio of the material's ultimate tensile strength to the Young's modulus.Upon trying this approach and running simulations with the adjusted value, I observed that the material seems to fail much more readily compared to my usual results.Could someone clarify why the recommended approach suggests using the ratio of ultimate tensile strength to Young's modulus for setting the Geometric Strain Limit value?Furthermore, I intend to apply this to collision analysis with a focus on the target's failure. With two materials involved, the colliding object and the target, which material's calculated Geometric Strain Limit value should be utilized?Thank you in advance for any insights or explanations provided.