ANSYS Direct Energy Deposition (DED) Additive Process Simulation

Hi everyone, this is Ming Yao from Ozen Engineering. In this video, I'll be looking at how to simulate a direct energy deposition additive printing process, simulating this process in ANSYS Mechanical.

ANSYS has a complete set of tools and features for additive manufacturing, so we're going to explore one of them today. Direct energy deposition is found in the custom systems section. AM, additive manufacturing, DED process.

This is similar to 3D printing using plastics, but the ANSYS simulations are set up more for metal additive processes. So we're going to open up this CAD model and go ahead and start setting up the simulation. Okay, so here is the model we're going to work on.

We're going to, this is the base plate down here. We're going to model the printing of this particular part. ANSYS has tried to make this process as easy as possible, so when you start a DED process, we have this additional tab that allows us to open the wizard for direct energy deposition.

As you saw in the picture there, maybe we should exit the wizard and look at it again. Right, this is in here, we have some sort of heater or laser with a stick of metal and we're melting it onto a piece, welding it onto the piece for this particular additive manufacturing process. So I'll go ahead.

The first part is easy. We're going to select the part we want to print and the base. You can see that we have detailed descriptions of what we're doing here down there. And automatically it's, it's created. It's created. We're creating name selections.

So this wizard is only adding features and capabilities into the tree. So you can go ahead and modify this at any time later on. So now we're going to mesh this, this part here. I'm going to set something like this. So there are a number of different meshing methodologies. We can use sweep mesh.

We can use tetrahedral mesh, Cartesian mesh or the default meshing. The goal is to have multiple layers through this thickness. So typically Cartesian meshing is a quick, robust and easy way to do this. The drawback is that we end up with voxels instead of having a smooth curve.

So you get some ideas of deformation and stress, but obviously you're not capturing the geometry as accurately as you would if you use some of the other meshing methods.

We could certainly use the other meshing methods to get clean mesh, but then if the geometry becomes complex, we can still work on it. You have to be a little bit careful about how you set up the mesh and how you create this. So, lots of drawbacks and options.

A key part of direct energy deposition is we're going to follow a particular path in the printing of this. So, for example, we can maybe print the circle and then print two layers down here, or we can do this, go up, do this, go up. You can kind of define the path of the machine.

The path is typically defined using a G-code, which I have here. Let me pull it over here. So I have just a regular text file. I can open this and that imports a G-code. Let me open up that text file so we can take a quick look at what the G-code looks like. So this is that text file.

It's a G-code that tells you the layer, where it's drawing, and the path that it's going to take. So it's a series of line segments as the machine goes through X, Y, Z, X, Y coordinate systems, and then periodically it will go up once it gets to the next layer, Z changes, the next layer, Z changes.

So that can be created by your particular machine. So that's the G-code. So, let's go ahead and take a look at the next slide. So you're going to see some of the underneighborhooding tables, less and fewer out in the ground, right? So, this is like a big cross section, right here.

So we have a line segment that's basically a grid composition here. I can now move the sprite array from right to left, right here in the grid. So as I start to see, I want to bring up the gray area. I'm going to also make sure that I'm somewhere. We have some background tests here. Right?

So I'm going to make sure that where there is a spawn row, the 90-meter range, and this right here is a full common area. We have strut in the square area, that's the deserves slat. You don't want to draw a divided line here, and that's is really main on thevenge button of the Java library.

You can draw a game here. of material in every element or do you want to do large segments? So if I make this large, for example, a thousand, instead of printing this one by one, we're kind of printing big strips and that makes the simulation faster.

If instead I do smaller values, we're going to be running many simulations as we slowly print each and every component. So a typical trade-off between speed and accuracy for simulation.

You can see as I build this G-code, I put in the G-code, it's identifying the upper and lower elements and it's setting up my G-code clustering, clustering settings and build settings.

We can specify the material engineering data or the material we're going to be using for this analysis and I think we're going to do Inconel. So Inconel 718 for both. You can have different materials if you wish and you can adjust these material data as well. Let me step back for a second here.

ANSYS has an extensive set of materials for these types of analysis. If I look at Inconel 718, I have temperature dependent density changes, temperature dependent thermal expansion coefficients, melting temperature, temperature dependent elasticity, temperature dependent temperature.

If I select the material itself, on the left hand side I have a whole host of other material models I can use including things like creep, maybe viscoelasticity.

So depending on what material characteristics you wish to capture, what type of amount of accuracy you need for the material properties, you can use more or less depending on how well the simulation represents your actual model. So that's it. So I'm going to go ahead and set that up.

Here now we can set up the machine deposition rate. This defines how fast my parts get built. So here I'm going to put 72. When I have a preheat temperature of 80 degrees and we're going to select the bottom face as this is the preheater temperature. And the process temperature.

And the water temperature is inside the operating pressureck mark. And I'm going to find the temperature. Here's my temperature earlier. And I'm going to say go with the peak setting. If the system diagram shows up here, I'm going to say stop.

I'm going to say constraint, underl na mabilITY is all right. I'm just going to turn it on. During my operation I'm going to use my right hand side ch account to free from this layer. no longer bonded to the base. In this case, I'm going to choose not to remove the base.

And that's it for my simulation. So I can go ahead and run the analysis. One of the things that we should do is take a look at the mesh, for example. So right now I have a coarse mesh, and just to show you the possibilities here, we can change this mesh to a different method.

So I'm going, we have a wide range of meshing methods in ANSYS. I'm going to put multi-zone. It's going to put a fully hex mesh. And the body sizing is specified here. I probably want something similar. I want three elements to the thickness, so I'm going to insert my own sizing here.

Maybe make it three millimeters. We want four elements, I should say. So I'm going to put three millimeters. Right, this is 12, so three millimeters is perfect. You can see when I change something in the analysis here, this one, let's go with the Cartesian method for that part.

So now our simulation is ready. So I'm going to go ahead and run the analysis. Looks like this contact got lost a little bit. It's not supposed to be defining the contact between this surface and the bottom surface. So I can just go ahead and select that geometry, for example.

And I can actually do the top geometry as well, but we'll leave it as is. So now I'm going to generate the G-code. So now this is reading through the G-code, and based on the mesh, slowly building up the model through the printing process.

So it's saying the first loop will print this section of the mesh. And one of the reasons I did this was I wanted to reduce the mesh count, so it runs a bit faster. You can see then we're going to do that loop.

We're going to then print this loop, this one, and you can kind of just walk your way down. And then we're going to do the middles. So that's all I need to do to do this simulation. We're going to do a transient thermal simulation first. Looks like I needed that DED contact for... I should...

When I changed the method, I changed the name, so it's not able to find it. But let's go ahead and look at the simulation here, global temperatures. Oh, it didn't quite do what I wanted to do. It's partly because I changed the name.

It was looking for DED underscore contact, so let's go ahead and change this name. Okay. Okay. Okay. Okay. Okay. Okay. Okay. Okay. Okay. Okay. Okay. Okay. And if I go back to my build settings, you can see there are additional options for doing thermal calibration for calibrating to your test.

There's preheat during printing. We can turn on radiation. Lots of different options available. Okay, there we go. So now we're seeing the temperature change as we build up this material layer by layer. So while this is running, we can take a look at the temperature profile that is running.

You can see that we've printed this much already. So it's printing along this line. You can see the heat path that we're exerting on the structure, how the temperature is getting spread around the base. And it's slowly printing out. Okay. So we're printing out. We're still on the first line.

I think my issue is the base is too refined here. Let's go find my mesh place here. This mesh setting probably could be much larger. And that's going to allow me to run my simulation faster. And I don't really care about what happens at the base anyways. Okay. It's doing the second layer.

So the second layer starts here, but that's after it's printed these two vertical ones, which is why there's still some residual temperature here. Okay. It's now up to that location.

So as you can see, it's modeling the printing process with some assumptions about how fast things move, how many elements it's printing, the amount of accuracy you want to resolve in the model. But the nice thing about this here is that we have a really clean shape.

So the deformation stresses and such is accurate. So it looks like this will take a little bit longer than I expected. I'm going to stop this and change the mesh here. This one. This is my base mesh. Instead of four, maybe I can change it to eight. Double it. Let's see.

Oh, that's going to be pretty big. Let's see if it'll be fine. Hide this. And select the space. It still changed it. It's still working. It's still working. Okay. Okay. Here we go. So, let's give it a look and see what the mesh looks like now.

So, we've gone to just 6,000 nodes, which is super small. If I go ahead and generate, it should produce very much the same G-code clusters as before. You can see that all the processes are faster now.

If I run the thermal simulation again, because there are fewer elements, the process should be much faster. Okay. So, here's the second layer getting printed. So, while this is running, I'll show you the results of the completed simulation.

This is with the more coarse, fine mesh, but with the robust Cartesian meshing method. Okay. So, Cartesian meshing again gives you really robust results, but all of those corners and angles will compromise the accuracy of the simulation.

But you can always adjust the meshing as needed, like you see here. Okay. So, here's the same model, but simulation process completed. The thermal simulation here was very fast. It took a matter of maybe five minutes. But the structural simulation took 1,200 steps, and it was on my four-core laptop.

It took a considerably longer time. It looks like the last time was 5,000 seconds. So, about an hour and a half, around there. So, this is the final result. You can see the coarseness of the Cartesian mesh. Here are the printing cycles.

I'm going to increase the resolution, and we can animate the printing process, which I think is quite beautiful. Layer by layer, modeling the printing and the temperature distribution of the entire system. Then this long drop-off is the cool-down once the printing completes.

So, at the end, we have almost the same temperature here. And then here is the deformation. Again, this is the printing process and the cool-down.

You can see that the residual heat builds up in the corners, and the fact that we have sharp corners here that doesn't quite represent the geometry gives us some interesting results. We definitely see some high distortion right over here, where the printing initially started.

You can also look at values like stress and strain. For strain, you can look at thermal strain, plastic, equivalent total, etc. So, if I look at the long Mises strain here, we can see the strain getting built up over the printing process.

It depends on if I print slower, perhaps this will be resulting in less residual thermal strain. And then, if I print slower, perhaps this will be resulting in less residual thermal strain. And then, at the end here, that's the final thermal strain.

If we do the base plate cut-off, we can remove the base plate, and this will return, distort to some sort of shape. I was talking to some customers interested in this capability. This is just a basic demonstration.

The simulation here is built into the ANSYS workbench mechanical environment, so it is extremely flexible. We can add various other features to this.

We can add various other features to this model as needed, whether it's meshing or other geometry features to model this process and add other loads if needed. You only need to use the DED process wizard to set up the basic 3D printing part, not the rest of it.

Hopefully this was interesting for everyone. Again, this is Mingyao from OZEN Engineering. If you like this video, please like and subscribe to our YouTube channel.

If you have questions about simulating 3D printing using direct energy deposition or similar type of techniques, you need help with it, please let us know at ozeninc.com. Thank you, and have a great day. Thank you.