I am currently running simple explicit dynamics impact test where I am impacting a rectangular sandwich on a rigid wall. I am trying to use hyperelastic materials and the data I have currently is only uniaxial. Using Mooney Rvlin 5 parameter curve fit, I am getting an icompressibility factor D1 of 0 which explicit dynamics solver does not accepts. What should I do to make it work?

I tried making it 1e-5, it runs but not sure if it is giving the right analysis results and what implications it poses. I would also appreciate if someone explains what this parameter exactly is.

]]>I am trying to perform a prestress explicit simulation but face Negative element density error and a warning in explicit as shown below. The model includes a socket and a screw(simulation uses ¼ model).

First step in static is a large deformation interference fit simulation between socket and screw.

Second step in explicit is to extract the screw from socket

By the way, the mesh is completed in Hypermesh, and if I suppress the prestress condition in explicit, there is no problem to finish the explicit simulation. I have attached my wbpz file.

Thank you in advance! Hope everything is doing well with you!

Please do help.

regards

PFA the files if you want to take a look at the soltuion

i used this link for reference https://youtu.be/EDtUeS9C_ik. Was unable to prepare the geometry please help its urgent

file is attached

]]>Hello Sir

I'm currently doing turning Operation on explicit Dynamics as part of my course project and I am facing a bit of difficulties

1. Instead of my workpiece, the tool is going through cutting operation ( workpiece is Cutting the tool)

2. And after getting the right solution from the processing previews, After a certain point of processing, "energy Error is too large" pops up... What should be done ?

P.S. I've given a displacement of 5mm for the tool per revolution.

So instead of giving a spindle.speed to the workpiece I'm using displacement in cylindrical co-ordinates to rotate it once a cycle to attain feed rate in mm/rev.

Please do help

Regards

Anurag Karulkar

]]>I have been applying pure shear shear boundary conditions for single element tests to both MAT 26 and MAT 126. However, it seems that both of them produce an overestimation in the results after a certain strain value. Does anyone have any idea why it could be?

I also applied a perfect plastic behavior in MAT 126 but the result is again repeatable.

My computer is running with Intel i7 and GTX 1050.

Here's the screenshot of my entire model and the "solver initialization error".

Here's is my solver output:

I need help ASAP. I can't seem to get what is wrong, is it my model or what? What should I do next.

P.s: I did uncheck the "distribute solution" box.

Please help me!

]]>A solid tube has an initial condition of an Angular Velocity of -36.65 rad/sec

The Remote Displacement ramps a rotation of -1800 degrees in 0.856 s

Doing the math on the angular velocity and the remote displacement, they both come out to be 350 rpm.

I expect to see a simulation where the solid tube has an uneventful time rotating. Instead the tube erodes away. I understand there will be some stress from the small amount of centripetal force and some Poisson ratio effect, but I didn't expect this:

What is wrong with this model? I know that @MAMIN219 wants to know the answer to this question. https://forum.ansys.com/discussion/21391/thermal-aspects-during-turning-operation#latest

]]>I'm struggling to run a simulation of leveling but I still encounter convergences issues:

*The solver engine was unable to converge on a solution for the nonlinear problem as constrained. Please see the Troubleshooting section of the Help System for more information.*

Thanks in advance for tips

I would be so grateful if anyone could let me know how to restore the project t the most recent solution.

]]>Respected sir @peteroznewman ,

After your Valuable feedback (ABOVE Discussion), I have started Drilling operation from one thesis which i am attaching here

In this above thesis , They have used structural steel NL as drill material and Aluminum 6061 T as workpiece. In this thesis they have used experimental method so I have referred this for drilling operation. Here above, for 60000 rotating speed ( angular velocity in RPM) and 200 * 12 =2400 mm/min feed rate. so actual time for drilling is 7.5 sec which is very comupatationly tough in explicit dynamics .So they have used 200 as factor multiplication is original 12 mm/min value .

Here my doubt is in experiment they have used 6000 RPM but in software they have used 60000 RPM Why?

In addition, Feed rate is 200*12 =2400mm/min but in ANSYS velocity is in unit with mm/sec and thesis sir has used 2400mm/sec which is little bit confusion for me. Is this correct if yes then have used 0.0006 sec end time

Please brief highlight on calculation of end time for drilling operation above.

while I am simulating this file in my PC I have found error of :"Time step Too Small"

Due too large file (Larger than 100 MB ) I am only attaching ANSYS 19.2 file with all boundary condition and mesh file. Please give your valuable feedback for validation of this.

In addition , They got 931.8 N Thrust force by taking Normal stress at bottom surface but only written in thesis like :

" the drilling tool diameter is 0.5 mm, therefore the thrust force is 931.8 N Can you please brief highlight on this

Here I am attaching My ANSYS 19.2 file for your reference. Please check this file and change if need and give feedback on my above mentioned doubt.

Once again Thanks for always share your knowledge with us and motivate us 😊.

With regards,

MIHIR AMIN

When using sloid elements as the master, is it neccessary for the mesh of solid part coarse than SPh particles?

I just need to the procedure for doing this meshing.

Thanks in advance.

]]>I'm doing a transient analysis in ANSYS Classic with a time step size of 0.001 s. However when I list the results (e. g. deformation uy by time) (command: "PRVAR") the results (of e. g. uy) are shown in time step sizes of 0.004 s. Is there a way to show the results every 0.001 s instead of every 0.004 s?

(So e. g.: t = 0 --> uy = 45; t = 0.001 --> uy = 50; t = 0.002 --> uy = 55)

Thanks a lot in advance.

Mirjam

]]>Impactor = Bar, 0.13kg, 50m/s Stainless Steel

Auxetic Structure = 0.23kg, Fix support at base with displacement control on both faces for planar simulation

Im also using explicit materials with principle stress failure of Al6060-T6

Is there a way to overcome this?

]]>Any way to solve it faster and get accurate results. Thanks.

]]>This is an example of dam break from https://www.dynaexamples.com/sph/intermediate-examples/wavestructure

]]>I am doing my thesis work on the steel-concrete composite beam under impact load and I am validating the experimental result attached below for specimen D31-0.7

]]>https://drive.google.com/file/d/1DM8EUbsYP0DI2R4b1pMq-PQTcRYN29Jh/view?usp=sharing

]]>Hello Ansys Student forum,

I would like to ask for some help in improving a simulation.

**Software:** Ansys Student

**Goal:** Simulate turning/wear on a small tool, with a constant applied force of a tool, a constant rotation of a workpiece.

**Simplifications:**

- Symmetry plane.
- Reduced sample to only a fraction of real diameter to accound for interaction and 1 degree of movement.
- Applied splits for (possibly) better mesh on tool.

**Challenges/questions:**

- The tool tilts and wobbles as though it is not on a fixed track.
- The workpiece seems unscathed.
- The simulation time for 1 degree of movement clocked out between 30 minutes to 50 minutes. Is there an obvious way to speed this simulation up? Or to analyze wear in a different, quicker simulation?

I will try attaching gifs, and images of the setup. I will attach a mesh statistic of characteristic length.

Thank you!

Don't know how to fix it. On startup of 2d LS-DYNA it says something like 2d for ls dyna is beta version etc. I'm using ansys wb extension for ls dyna.

Thanks.

]]>(1) I am modeling a disc cutter (FEM) cutting rock block (SPH), and the interaction between rock and cutter is defined with *CONTACT_AUTOMATIC_NODES_TO_SURFACE, fs=fd=0.3. The expected rolling force (contact force in the Y direction) should be always positive or negative (depends on it from slave or master). However, my results show that the Y force fluctuates around zero. Could you give me some suggestions?

(2) Rock block consists of SPH part and FEM part, why there is a gap bewteen SPH and FEM in post-processing? It seems that some particles disappeared. Their interaction is defined by *CONTACT_TIED_NODES_TO_SURFACE.

I have attempted to change the thermal solver from nonlinear to linear and implemented various thermal solvers other than the default but none of these combinations had a significant impact on the findings. Modifying the thermal timestep and inputs in the *CONTROL_ALE command also had no impact on the results. A brief presentation is attached to this post, which illustrates the above points, along with the current input deck for our Eulerian simulation. The analyses are performed using a double precision, SMP version of R10.1. Based on our current attempts I am unsure of there is an issue/shortcoming with our modeling approach or if this is potentially associated with the solver. Any suggestions or insights would be greatly appreciated.

@peteroznewman Sir i have tried with 12 mm tool travel nut still my tool is not travelling

and actually distance between that two vertex is 6.8 mm which you have mentioned in last discussion.

here i am also attaching my ANSYS 2019 file.

please guide me why this things is happening

if you find any mistake please change it and send with me for better understanding.

Please answer as soon possible.

Give regards

Mihir Amin

]]>Based on this study, the explicit solver can can sucessfully predict springback of sheet metals with nonlinear materials. Compared with traditional dynain implicit method, they give the same predicition. However, seamless springback analysis did not predict the the springback correctly. Your comments are highly appreciated.

]]>I have to simulate an impact of a pendulum on a test piece. Normally, it wouldn't have any problem, but the impact has to be repeated. That is, the pendulum strikes the specimen, returns to the initial position, and strikes again. This process is repeated for X times. Which tool can I use to perform the test? Explicit dynamics? Static structural? I really don't know...

Thank you very much.

]]>I'm working with THUMS (Total HUman Model for Safety) v5.03 in LS-PrePost 4.5 , and I noticed the available positioning tool specified for this human model. I usually work with the Hybrid III dummy's positioning, but it is not the same for the THUMS positioning tool as it doesn't find information about joints, hence I can’t change limb orientations. (whereas the H-point still works).

I couldn't find anything to solve this issue in either the manuals or the user guides. Could you give me some help?

]]>I was trying to simulate a vibration of plate with initial strain(e_xx) condition.

For this, I'm thinking to apply linearly varying displacement as a function of X coordinate. I'm unsure how to apply this displacement as an initial condition. I see that there is an option for initial velocity.

Could you let me know if there is any approach to model initial displacement.

]]>Please does any one knows if it is possible to use more than one node on cluster?

I have been trying it out but all efforts to no avail.

Thanks a lot for your help.

]]>Can you look at the video and tell me what's wrong. Tool is not cutting the work piece

]]>I would like to apply Velocity as a function of space on of the faces/edges of my model. In ANSYS LS-Dyna Extension, the only Option is to give Velocity as a function of time in Tabular form.

How can i proceed?

]]>I have questions regarding my meshes involved in an interaction between a rotating cylinder sample and a small tool. **Also if you have any comments as to the way I am approaching this simulation, please feel free to provide your input!**

I have attempted to section my models to generate a better hex mesh.

My concern is that the mesh of my tool is finer than my sample. Also, my sample does not have layers at the surface of interaction. Should I consider layers where the sample would be machined?

As a side note, I have the student copy of Ansys and the scale of this analysis is quite small. I am primarily interested in the stresses, strains, and forces in the tool.

I would appreciate your input. 😀

I encountered a problem, while try to use CONTROL_REFINE_ALE. I try to simulate wind blow flat plate. Without CONTROL_REFINE_ALE, simulation works fine. After added this keyword, the simulation seems stuck in the pre-process. No warning or error message either. Don't know if you guys know how to fix this. Any advise will be welcome. Thanks a lot.

]]>I was wondering if anyone has come across the following message when running an S-ALE simulation in LS-DYNA? It appears that the model runs fine and I do see any obvious errors when looking at the GLSTAT results so I am not to sure what purpose of this message is:

something wrong...salecpl_getvfpt, pd<0?, pd= -1.292409509211626E-016

The number after pd seems to change every time I get the message.

Thank you!

]]>

I have attempted to change the thermal solver from nonlinear to linear and implemented various thermal solvers other than the default but none of these combinations had a significant impact on the findings. Modifying the thermal timestep and inputs in the *CONTROL_ALE command also had no impact on the results. A brief presentation is attached to this post, which illustrates the above points, along with the current input deck for our Eulerian simulation. The analyses are performed using a double precision, SMP version of R10.1. Based on our current attempts I am unsure of there is an issue/shortcoming with our modeling approach or if this is potentially associated with the solver. Any suggestions or insights would be greatly appreciated.

How can I have a more data Points in my results so that I can plot smoother curves?

I have tried different Things but number of data Points remain fixed at 21.