OreSat

The old design creatively used a 'wedge' and a 'triangle.' When tightened, the wedge would push up the triangle, and there would be a clamping force holding the card to the frame. 

This design had a few headaches. One was that the triangles were very small and were hard to keep in place. During assembly, the triangles would have to be held in place while it was put together. A particularly disastrous accident was when a triangle fell out during a handoff to a launch provider. The team was able to reassemble the satellite with the triangle secure, but it was clear that the triangles were a very hindersome aspect of the design.

Another problem with the old design is that it had a high number of unique custom hardware that needed to be manufactured. The inside of the satellite is very dense with subsystems, and there were many different types of wedges and triangles to fit in different spots. 

I co-authored a grant from NASA through Oregon State University. We were able to secure $9,965 in funding for optimizing OreSat's structure. 

The team had decided integrating the triangle into the frame and consolidating hardware into two versatile pieces was the most effective way to accomplish our objective. One of the most important criteria of our design was to analyze the forces in the hardware and select an angle that would provide the most clamping force. 

The temperature of the different pieces of the satellite is information that is especially important to the electrical engineering team of OreSat. It was our duty to come up with simulations to inform their design choices. 

Using the program ThermalDesktop, we were able to simulate complex orbital heating scenarios with ease. OreSat0 was launched near the beginning of our capstone and was relaying us temperature data on space. We used the data to converge our simulations so that they can be used to accurately simulate future missions. 

For the orbital simulations the thermal contact resistance between every touching component needed to be experimentally found. The thermal contact resistance is a function of materials touching, their respective surface roughness, the pressure pressing them together, and the medium of the fluid that exists between them. Because of this complex relationship, there are no tables that list every possible combination, so the team set out on experimental methods to determine them. 

Vibrational analysis was done on the frame assembly to make sure that it was not vibrating at one of it's natural frequencies during launch. The natural frequencies were compared to ones supplied by the launch provider. 

Axial loading was also ran through FEA. Every CubeSat must meet a minimum axial compression strength in order to withstand other CubeSats stacked on top of it. Our FEA showed that it met the requirements and then some, being able to support 6,o00 pounds with the old design and 4,000 pounds with our new redesign. Although our designs reduced it's compression strength, it is still much stronger than necessary and could be used as a car jack. 

We wanted to make sure that the new wedge design would not yield under the specified torque so FEA analysis was done on the wedges as well. 

Before we spent the majority of the grant money on manufacturing the frames, we created prototypes to ensure that they would work. We used FFF 3D printing and a SLA prints for higher resolution. We presented these 3D printed parts to the rest of PSAS for any criticisms and their approval. 

With all of the changes we made, there was a 35% cost reduction for the entire OreSat structure system!