> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ntop.com/llms.txt
> Use this file to discover all available pages before exploring further.

# How to shell a lattice to get a shell mesh and connect it to a solid mesh

## Objective:

Learn how to create a surface mesh of a gyroid body and tie it to a solid mesh

## Applies to:

* FE Surface Mesh
* Tie Constraints
* Gyroid Body

## Procedure:

1. \*\*Shell a Gyroid Body:\*\*Use the **Gyroid Body** block with **the Set Body Bounding Box.** We use the Set Body Bounding Box as the Gyroid Body block creates an infinite field.

<Note>
  *Note: **Set Body Bounding Box** is only used to visualize the infinite field in the defined Bounding Box. You must use a **Boolean Intersect** block to intersect it to the design space.*
</Note>

![An image of a gyroid model next to the nTop notebook.](https://files.learn.ntop.com/help-articles/structures/41634329800595.png)

If you use a Graph Unit Cell, you can use the ***faces as mesh*** property to obtain the shell mesh you need.

![A image of a periodic lattice block and its properties panel. The image is showcasing how this lattice type allows the user to extract a faces as mesh property chip.](https://files.learn.ntop.com/help-articles/structures/37946064769555.png)

![The Faces as Mesh property chip visualized as a mesh](https://files.learn.ntop.com/help-articles/structures/37946064778515.png)

2. **Creating a Surface Mesh from the Gyroid Body**

Use a combination of **Mesh from Implicit** **by DC** and **Remove Mesh Faces by Body** blocks as input for **FE Surface Mesh.**

![The image shows an nTop notebook with two meshes. One mesh is generated from the Mesh from Implicit by DC block. A Remove Mesh Faces by Body block is then used to extract only the surface mesh.](https://files.learn.ntop.com/help-articles/structures/37946112094483.png)

I suggest reviewing this article to learn more about meshing ([**Methods for creating surface meshes).**](/help-articles/knowledge-base/meshing-workflows/methods-for-creating-surface-meshes)

**3. Creating a Solid Mesh:** We create Solid Domains with Solid Attributes for the Top and Bottom Boxes.

![The image shows an nTop notebook next to a model of a gyroid in between two blocks. The model is a Simulation model, showcasing the connection nodes between the gyroid and the blocks. ](https://files.learn.ntop.com/help-articles/structures/41634329802387.png)

4. \*\*Connecting the Surface and Solid Mesh:\*\*Use the Tie constraints to connect the Surface Mesh to the top and bottom bodies.

Use the **Simulation Model** model with three domains (Top, Bottom, and Gyroid). We are choosing appropriate Shell and Solid attributes. ([How to create an fe model for a simple shell lattice](/help-articles/knowledge-base/structures/how-to-create-a-simulation-model-for-a-simple-shell-lattice))

The first tie constraint is used to connect the Top and Shell Mesh, and similarly, the second one is for the bottom. ([Methods for connecting multiple FE meshes in an fe model](/help-articles/knowledge-base/structures/methods-for-connecting-multiple-fe-meshes-in-an-simulation-model))

![The image shows an nTop notebook next to a model. The image highlights the Tie Constraint blocks that are used to connect the separate FE Meshes through contacting nodes.These nodes are connected using Tie Constraints.](https://files.learn.ntop.com/help-articles/structures/41634329804819.png)

![The static analysis results of the Simulation Model](https://files.learn.ntop.com/help-articles/structures/41634350037651.png)

And that's it! You've successfully created a shell mesh of the gyroid body.

Are you still having issues? Contact the [support team](https://support.ntopology.com/hc/en-us/requests/new), and we'll be happy to help!

## Download the Example file:

* [Example file](https://files.learn.ntop.com/Support%20Article%20Example%20Files/Knowledge%20Base/Simulation/Shelled%20TPMS%20Connected%20to%20Solid%20Mesh%20Example.ntop)

## Keywords:

*mesh surface lattice boundary body shell fe constraint solid tie how-to*