Astronaut’s Coatrack
Class: 24-370, Engineering Design I
Task: Design an acrylic part that will hang from pegs on a wall and will support a 40 lbs weight (the weight of an astronaut’s suit), while also optimizing to make sure the part is as light as possible.
Medium: Pencil, Solidworks, Acrylic (laser cut)
Here are a few of my initial idea sketches. I focused on creating pieces that would be safer (lower chances of failure). My plan of action was going to be find a design that worked well, and then modify to optimize for weight. Based on the grading system, I figured I should prioritize the part actually supporting the weight rather than being incredibly light and risky.
Here are the two ideas I decided to proceed with. I started by doing some rough calculations to make sure they were going to be somewhat safe.
I quickly noticed that the idea pictured on the right seemed like a safer version of the idea on the left. I wanted to see both in CAD and also do some FEA analysis.
As you can see below, the FEA analysis shows that this part will be very safe and will come nowhere near to breaking under the 40lb load. SO I feel safe in calling this the back up plan. I wanted to make sure that I had a back up plan that I was confident in before pursuing a lighter option
So I started to pursue the lighter idea. I started with a simple CAD and ran some FEA analysis, pictured below.
We can see that this idea is less safe than the back up plan, but the numbers from the FEA are saying that the piece should be able to hold.
To further test the idea that I could get rid of a lot of weight in the middle, I printed my first idea, and tested it to failure. As expected, the sides broker before the middle, telling me that I could stand to reduce a lot of the weight from the middle of the piece.
Here is the final product, laser cut out of 3/16” acrylic.
Unfortunately, I no longer have any photos of it in the real set-up, so here is the testing rig in Solidworks, with my project inserted.
Conclusion:
My design did end up being able to hold the 40 lb. weight. I also ended up finishing 4th in the class (out of about 45 students). I was really surprised by how light I was able to get my piece while still maintaining strength in all of the important areas.