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Question:

Is blending edges or adding a fillet to lattice nodes and beams possible?

Applies to:

  • Implicit modeling

Answer:

We recommend three methods for applying fillets to lattice structures. This article will walk through each method to help show their differing results.

Method 1: Blend Intersections

Note: This method is only applicable for Graph Unit Cells.
1. Create your Periodic Lattice with a Graph Unit Cell or a 2D Unit Cell (How to create a periodic lattice and Guide to Rib Design) The starting lattice that is unmodified. 2. Add a Blend Intersections block. Lattice input is the Swept Ribs we created from the Ribs from the Graph block. Blend radius the filetting we are applying to the Ribs. The starting lattice with a blend intersections block applied. 3. Boolean Intersect with Offset Body and the Height as distance input. An offset body is applied to the starting geometry. A boolean intersect is used with the offset body and blend intersections lattice. The result is a lattice with fillets between the nodes and beams. The offset body removes the spherical shape the nodes have, and the result is a flat node.

Method 2: Custom Unit Cell (Resource Intensive)

1. This method is based on smoothening an unit cell and then using that unit cell to create a lattice. For this example, we start with a generic Rectangular Volume Lattice. The lattice volume is scaled up to create a correctly proportioned unit cell later in the workflow. We convert some of the inputs from the workflow into variables for easy lattice modification at the end. Note: TheCustom Unit Cell Method requires significant computation power and takes longer to process. A starting rectangular volume lattice. 2. Next, we use a Trim Lattice and Box block to create a sample section of the enlarged lattice. The Box is larger than the unit cell to ensure all of the necessary beams will be present when creating the lattice. A sample of the lattice created in step one. The sample is taken by trimming the lattice using a box as the domain. 3. Using the start and end points of the lattice sample, we can generate cylinders in place of the original beams. This will allow us to apply the radius to the sample when the cylinders are combined in the Boolean Union. A gif showing the extraction of the start and end points of the lattice sample. Using the start and end points of the lattice sample, we can generate cylinders in place of the original beams. 4. Now that we have the smooth sample lattice, we can create a Box the size of the unit cell. The Bounding Box of that Box is now the defining boundary of our Custom Unit Cell. Creating a box using the unit cell size. The box's bounding box is then extracted to use in creating the Custom Unit Cell of the Sample Lattice. 5. We can now generate the smooth lattice using the Rectangular Volume Lattice. For this example, we just used a Box as the body to generate the lattice from. Depending on your design, this may be the final necessary step. To close the open beams, continue with the last two steps. The rectangular volume lattice is then generated using the custom unit cell. 6. The Initial Smooth Lattice is made of the Custom Unit Cell we generated. This contains no beams because it is made of the merged Cylinders. To fix this in the next step, we can create a Reference Lattice using the original Unit Cell. Now that this lattice has beams, we can use the Filter Beams by Connectivity block to remove the open beams. Creating a reference lattice from the rectangular volume lattice. The reference lattice is then used in a Filter Beams by Connectivity block to remove any open beams. 7. The final step is to use a Boolean Intersect with the Initial Smooth Lattice and the Closed Reference Lattice. This results in the lattice having fillets at the nodes with the removed open beams. A Boolean Intersect block is used with the initial volume lattice and the closed beams lattice to create the final body. Are you still having issues? Contact the support team, and we’ll be happy to help!

Method 3: Spheres

1. Start with any lattice structure you want to thicken the nodes. For this example, we will be using a standard Periodic Lattice. You can see some of the inputs from the workflow have been turned into variables for easy lattice modification at the end. An example periodic lattice to start from. 2. We will extract the vertices from the properties panel using this lattice. These vertices are then used to generate Spheres , which we will Boolean Union together to create one body. The gif shows how to extract the lattice beam vertices. The vertex point list is inserted into the center point of a Sphere block. This generates a sphere list, the list is then merged into a single body using the Boolean Union block. 3. To generate the final lattice, we use a Boolean Union to combine the Spheres with the Periodic Lattice. Then, using a Smoothen Body block, we can create smooth fillets between the nodes and the beams. The fillet size can be adjusted using the Grid size and Smooth iterations inputs. A larger grid size makes more drastic fillets, while a smaller one will create gentler fillets, increasing run-time. A Boolean Union block is used to merge the original lattice with the spheres. The final step is to smoothen the merged body.

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Keywords:

implicit blend body offset smoothen geometry basic lattices edges fillet