> ## 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.

# FE Meshes

Creating an FE Mesh is one of the first steps in setting up a Simulation or a Topology Optimization. The image below shows the basic steps for creating an FE Mesh. If you are working with a solid body, we recommend the **FE Volume Mesh**, and for lattices, we recommend **FE Lattice Mesh**.

<Frame>
  <img src="https://files.learn.ntop.com/lessons/fe-meshes/102_19_FE-Mesh-Chart.png" />
</Frame>

## FE Volume Mesh

The **FE Volume Mesh** block places FE elements over volume mesh elements. The geometric order defines the number of nodal elements placed in the mesh elements.

<Frame>
  <img src="https://files.learn.ntop.com/lessons/fe-meshes/102_19_FE-Volume-Mesh.jpg" />
</Frame>

## FE Surface Mesh

The **FE Surface Mesh** block creates 2D surface elements with 'isoparametric' elements. The thickness defined is normal to the surface in the Shell Attribute.

<Frame>
  <img src="https://files.learn.ntop.com/lessons/fe-meshes/102_19_FE-Surface-Mesh.png" />
</Frame>

<Note>
  **Note**: The toolkit block **FE Shell Mesh** remeshes and creates a surface mesh using the block above.
</Note>

## FE Lattice Mesh

The **FE Lattice Mesh**block creates beam elements coinciding with lattice beams. The thickness of the beams is defined in FE Attributes (can be nonuniform).

<Frame>
  <img src="https://files.learn.ntop.com/lessons/fe-meshes/102_19_FE-Lattice-Mesh.jpg" />
</Frame>

## Merge FE Meshes

When some regions are easier to mesh than others, you can mesh them separately and join them using **Merge FE Meshes**. This process is good for interfacing surfaces.

<Frame>
  <img src="https://files.learn.ntop.com/lessons/fe-meshes/102_19_Merge-FE-Mesh.jpg" />
</Frame>

To merge, at least one node from each mesh must be within the distance threshold. Use distance threshold of at least ½ of mesh size.

<Tip>
  **Tip:** **General rules of thumb for elements in FEA**
  \*\*Thermal:\*\*at least 1 element across thin or small design features and or parts. Typically linear, unless you start to tie in deflection or stress due to thermal distribution.
  \*\*Deflection:\*\*at least 3 elements across thin or small design features and or parts, and is typically linear.
  \*\*Stress:\*\*at least 5 elements across thin or small design features and or parts. In nTop, use the Quadratic Geometric order (i.e., Mid-side nodes).
</Tip>