Ansys Autodyn Explosive Simulation 3D Ansys Workbench

Hi, this is MingYao from Ozen Engineering and in this video I'll be showing you how to set up a 3D explosive simulation in AutoDyn. We're going to pick up where we left off last time with a 2D analysis and I'll just duplicate these first two blocks. We're going to make some changes in the geometry.

In the 2D analysis we specified that the 3D components aren't going to participate in the simulation so we're going to have to undo that in this model. We no longer need our 2D surfaces and we'll select our 3D components and activate them for physics. So right-click "Suppress for Physics".

Going back to Workbench, I want to double check the properties. Right now the analysis type is set to 2D. We'll switch that to 3D. And now we can go ahead with our setup. All right, we have a model here and let's work our way through it.

So we're going to drag this model down from top to bottom here. This is our copper liner. We have the sphere which we made a plastic.

And then we have an explosive material here, C 4. So that's all defined as I've shown in the previous video and you can look at some of the information here in the material section. We don't need any contacts. And we can typically just use some of the materials. The analysis is set up here.

The key thing here is that we want to use the SSExplicit dynamics simulation which is available in Mechanical Enterprise. You can see this is the license currently used. But this license does not allow advanced simulations like the multi-material Euler simulation we're going to do here.

So we need to come out of this and switch to a different license. You see a license preference here and we're going to specify autodyne prep-post. Using the autodyne prep-post license allows us to set up a simulation as a multi-material Euler, so we can model an explosive simulation. Okay.

That was it. Going back to this, another thing that I forgot to change is that we need to select all of the parts and set this to Eulerian material. And then when we go to our analysis settings, you can see the Eulerian domain getting defined for me automatically.

We can display where the global coordinate system is right here. So we want to move the coordinate system somewhere over here and create a box that encompasses this model. If we scroll down the analysis settings, the end time is set to be a fairly short duration.

Everything else is set left as automatic. The domain size needs to be set to manual. And we're in millimeters here. So if I look at what a 10mm box looks like. You can go back and you can see that's starting here 10 by 10 by 10. So we want to adjust that accordingly.

If I click on a point, we can see that this vertex is a 0, -14 and 0. So let's go ahead and try to change that. So if I do, for example. We switch to that. You can see we're now here. So we want this to be on the Z axis to be over here. We want to extend the Y axis and the X axis looks okay.

So we need to shift this whole box over a little bit. So let's go ahead and do that. So that means the Z axis should be, let's say, -15 and we'll make it 15. So we're going to do that. And we're going to do that. And we're going to do that. 15 units in length here.

So now we have two surfaces that lie right on the symmetry planes. We can adjust the Y axis. So right now, Y starts at - 14. Let's go to -20 and we'll make it, let's say, 35. See how this looks. Okay. And perhaps we make this a little bit less. It's symmetric. So 10 millimeters looks okay here.

So if we make this 10, we have to make this - 10. And that then gives us a volume to consider. So we have our linear volume size. We want to make the -X face a real volume. We want to make the X face a rigid face. And then the kind of upper Z a rigid face.

So this simulates as if it's symmetry and the outflow will be in all of the other areas. So that's all we need to do for this analysis. The last part we want to define is the detonation point. So we want to detonate somewhere around here, but a little bit up.

So this is -13, 0, -13 would be a good place to detonate. So let's go ahead and say detonation point. Let's set it to 0. And you can also click on location to change. So if we click here. But I'm going to. Maybe, maybe 12. That's a good point.

So we're going to detonate the initiate the detonation here. And this is this is now all that we need to set up our simulation. The other thing we want to do is that the Euler domain remeshes the model. If we zoom in, it shows us how big the elements are in the simulation.

We'll have very large segments like this. We're not going to capture the spherical nature of our plastic very well. So maybe if we go up to 750, 000. You can see now the mesh is much closer. So you may need a fairly dense mesh for 3D simulations to run this accurately.

The nice thing about running these simulations in Workbench is that it is automatically distributed and paralyzed. So we can just go ahead and hit the solve button. The last thing we want to double check here is that right now we're only saving 20 results. That's probably far less than what we want.

So let's go ahead and do 200 results for the simulation. So this is running. We can see that the time steps times have shot up dramatically. Initially, the estimate was about 45 minutes. Now it's going to take about an hour to run. There's a thing that we want to adjust here.

So I'm going to stop the simulation. And I'm going to hit the save button. Now in analysis settings, I've run this simulation before. And one issue I've run into is that when the material starts to deform, sometimes you may get unrealistic velocities in the analysis. There's a way to limit that.

There's a maximum velocity cutoff. Switch to meters per second. Now the default velocity is extremely high, which means that if there's some numerical issues in the analysis, you may get very high velocities. And that causes the simulation time step to drop a great deal.

You typically want to reset this maximum velocity so that the simulation finishes in a reasonable amount of time. We want to set it to be maybe twice the detonation or burning speed of the material. And in this case, C4's detonation velocity is on the order of 8,000 meters per second.

So if we make this, for example, 16,000 meters, that's considered a reasonable number to have the maximum velocity. So with that said, let's go ahead and stop the simulation again. Okay, the simulation is completed. I reduced the mesh count to half a million cells.

In this simulation, it took about two hours, two and a half hours to run. So let's take a look at the results here. We can plot some of the standard deformation, for example. Other results we can look at include, we can go to the worksheet view.

So because this is an explosive simulation, it's often helpful to look at the pressure. And we can add a few of these all together. So alpha is another good... It tells us when the detonation of the explosives. And... Okay, maybe a plastic tree. We can see the explosion here.

Let's take a look at the alpha. See how much of it is detonated. And plastic strain energy. So we can look at the data through the workbench environment. We can also bring this information into AutoDyne. Now we can run AutoDyne on the computer. Either in the simulation or outside of it.

I'm going to save this project. Then we can open up AutoDyne independently. I'll just go ahead and do that. AutoDyne. Let's try this again. R 2. We can just go ahead and open up AutoDyne as a stand-alone system here. And we want to load the result files. So if we go to View files.

You can see this is now System E. And these are all the AutoDyne results. So I can copy and paste this into my Result Viewer. And we can go ahead and pick any of these. So let's go ahead and maybe do the final one here. And see we can go to a previous cycle. Now we're plotting the material location.

We can plot the contour of pressure as well. So you can make use of the full AutoDyne capabilities for post-processing. And step through a few time steps and see what happens. I'll go to Status and I should have clicked on Location here. There you go.

We can also use the AutoDyne option to create movies. So AVI, MPEG, or animated GIF files. So this is a quick example to show you how to set up an AutoDyne simulation in 3D using ANSYS Workbench. We can then post-process the results in AutoDyne which gives you a lot more flexibility.

I hope this was helpful. Please contact us if you have any questions. We're at www.ozininc.com Take care. Bye bye.