Designing My Own Tent Stake in Altair Inspire

How implicit modeling can optimize outdoor goods.

Altair has sponsored this post.

I have always loved the outdoors, and when I am not working, one of my favorite hobbies is to go backpacking in the mountains—specifically long-distance backpacking. I have done a variety of trips in my lifetime, ranging from short weekend trips to months-long excursions. Each time I go, I am always struck with how important weight is when you are hiking up and down mountains. For reference, I have hiked nearly 1,500 miles of the Appalachian Trail’s 2,190 miles. The elevation of that trip was about 235,000 feet of change, or the equivalent of scaling Mt. Everest eight times. So, while a few extra grams here and there may not seem like much, when you are hiking many miles with large elevation changes, you will feel every gram!

My backpack on the Appalachian Trail in Shenandoah National Park. (Image: Drew Buchanan.)

My backpack on the Appalachian Trail in Shenandoah National Park. (Image: Drew Buchanan.)

There are so many ways backpackers can reduce weight, and outdoor goods manufacturers prioritize this with new product designs. Every time I am in an outdoor goods store, I notice there being new products using advanced materials, as well as innovative product designs to reduce weight while maintaining strength. One product which has had numerous product evolutions since I began backpacking has been tent stakes.

You might be surprised to know that effective tent stakes are vital to backpacking. Non-freestanding tent stakes, popular for backpacking, require stakes to properly support a tent’s frame. This is opposed to conventional freestanding tents, popular for campers, where the stakes are not required to support the frame. Since non-freestanding tent stakes are vital to the frame, it’s important that they are strong, but also lightweight. Personally, I run titanium tent stakes which are reasonably light, but they are also expensive compared to other tent stake materials like aluminum. That said, my tent stakes have been very reliable as they have encountered various conditions like advanced terrain, hot and cold weather—and even the occasional wild animal!

Wild horses near my tent on the Appalachian Trail in Grayson Highlands State Park. (Image: Drew Buchanan.)

Wild horses near my tent on the Appalachian Trail in Grayson Highlands State Park. (Image: Drew Buchanan.)

Manufacturers face challenges when designing reliable tent stakes for backpacking. To satisfy their customers, they must look for innovative ways to maintain strength while reducing weight. They must weigh the options of picking a heavier, bulkier aluminum stake, or a lighter but more costly titanium tent stake. The challenge with these products and materials is that they are not the easiest or most efficient to manufacture.  

How Additive Manufacturing and Implicit Modeling Can Fix This Problem

The advent of additive manufacturing has changed so many industries, as companies are now able to 3D print designs that were previously impossible to manufacture. One of those specific new designs has been the lattice. Lattices reduce the overall material and weight of an object while still helping maintain stiffness and strength of a material. Prior to 3D printing implementation, lattice design was limited and could not be applied to many designs. It was too complicated to produce with traditional manufacturing methods like machining and casting.

Example of a lattice design. (Image: TrueInsight.)

Example of a lattice design. (Image: TrueInsight.)

With the ability to manufacture lattice designs efficiently through additive manufacturing, a new problem emerged: lattice CAD model creation. Designing lattice in traditional CAD modeling (explicit modeling) was not efficient. For explicit modeling, every single vertex must be defined in the software as an x, y and z coordinate. Thus, if you have a complicated lattice design with hundreds, maybe thousands, of vertices then explicit modeling will fail due to the large graphics or file size requirements needed to capture every single point.

As a result of the limitation in characterizing lattice with traditional CAD modeling, a new technique was put together to model lattice: implicit modeling. Implicit modeling characterizes the CAD model through mathematical equations rather than every single vertex.  As a result, users can model highly advanced lattices which would be nearly impossible to do in explicit modeling.

Designing a Tent Stake with Implicit Modeling

With the use of implicit modeling, I wanted to investigate if I could take an existing tent stake and design a lattice which could reduce weight but also be produced with additive manufacturing. Altair Engineering recently released Inspire 2023, which has implicit modeling capabilities built into it. I thought it would be the perfect tool to design this tent stake. Since Inspire previously had existing explicit modeling capabilities, I began by modeling a straightforward tent stake. I did this through a combination of extrusions, revolves and even the PolyNURBS functionality for smoothing out surfaces.

An explicitly modeled tent stake. (Image: Drew Buchanan.)

An explicitly modeled tent stake. (Image: Drew Buchanan.)

The new Implicit modeling ribbon in Inspire 2023 was a substantial release, as it contained implicit modeling capabilities for surface lattices, planar lattices, strut lattices, point cloud lattices and advanced field parameterization. Additionally, since the ribbon is fully integrated into Inspire, users can utilize other features, like simulation or explicit modeling. In the case of our lattice, I wanted to cut the weight by about 50 percent with a uniform extrusion of lattice through my tent stake, so I decided to utilize the planar lattice.

 Altair Inspire 2023 implicit modeling ribbon. (Image: Drew Buchanan.)

Altair Inspire 2023 implicit modeling ribbon. (Image: Drew Buchanan.)

I clicked on the planar lattice icon and selected the part which I wanted to apply the lattice to. In my case I only had one body, so I clicked on the tent stake. The planar lattice dialogue box popped up and I had several different settings available to adjust my lattice.

Planar lattice options. (Image: Drew Buchanan.)

Planar lattice options. (Image: Drew Buchanan.)

For a planar lattice, there are several different types of unit cell lattices; I could easily change the unit cell type and decide if I wanted to utilize a regular setting or to invert the lattice creation. Additionally, because Altair Inspire utilizes GPU capabilities, I could change lattice types and settings on the fly and not waste any time for the computations. I ultimately liked the settings for the hexagon unit cell the best, so that is what I chose.  Additionally, I chose a lattice size of about .02 inches, which reflects about a 50 percent reduction in mass to my part.

Different types of planar lattices. (Image: Drew Buchanan.)

Different types of planar lattices. (Image: Drew Buchanan.)

After I generated my lattice part, I wanted to 3D print a prototype to try out for my next backpacking trip. The implicit modeling ribbon has specific commands to make the 3D printing of lattice creations as efficient as possible. This includes specific commands such as lattice smoothing, morphing and setting print resolution quality.

In my case, I specified a smoothing constant to my part to eliminate jaggedness. I also applied a high-resolution quality to ensure a nice print. The other great thing about the Inspire implicit tool, is that there is a dedicated construction history, so if users want to change any modeling settings, they can do so by clicking on any object in the construction tree and making changes to the implicit settings.

Construction history of the hexagon lattice. (Image: Drew Buchanan.)

Construction history of the hexagon lattice. (Image: Drew Buchanan.)

3D Printing an Implicit Modeled Tent Stake

Our final step before we went to get this part printed was to save the lattice format to an acceptable file for 3D printing. Implicit modeled parts can be saved in a variety of printable formats, but in our case, I chose a .3mf file since it an ideal format for my build.  Once my part was saved, I was able to get this part printed with GoEngineer. The final print came out beautifully. I was able to test this tent stake out in the wild, and the design performed great; no deformation and it supported my tent completely. Additionally, I think the lattice looks pretty darn cool. I have never seen another tent stake like this before!

Finished 3D printed tent stake (left), and field testing (right). (Image: Drew Buchanan.)

Finished 3D printed tent stake (left), and field testing (right). (Image: Drew Buchanan.)

With the use of Altair Inspire’s new Implicit Modeling capability, I was able to generate a new and unique lattice very quickly. Additionally, I was able to generate a part that could be exported and printed easily by a 3D printer. The lattice maintained the strength properties I needed for my tent stakes, but also cut the weight by 50 percent. If I can generate and create this unique tent stake on my own, I am excited to see what large companies for outdoor goods can do in the future.

To learn more about Altair Inspire Implicit modeling capabilities and other simulation driven tools visit Altair.com/inspire.


About the Author

Drew Buchanan is an engineering manager at TrueInsight.