Astronaut's Coat Rack

Project for 24-370: Engineering Design I

Task:
To design a bracket (astronaut's coat rack) that will support a suit clip loaded with 40 ± 1 pounds force directed downward, one time, without failing, for at least 10 seconds.  The bracket must not interfere with the forbidden zone (shown below in red), and the suit clip must not move more than 0.25 inches from its initial position.  The bracket will be mounted to the support structure on either side by socket cap screws.

The Testing Rig

Iteration, Iteration, Iteration!
Over 50 Prototypes were Laser Cut!      (click to see photos below)

A lot of work was put into achieving the final design.  Major modifications were made with mass minimization in mind.  Firstly, the bottom beam was shortened significantly to decrease both its magnitude of buckling and the part's mass.  Also, its width was increased at the center to resist buckling, tapering off on both sides.  On the other hand, the width of the top beam was decreased because it supports solely tensile axial loading.  The profile around pin supports were refined to reinforce specifically locations that experience critical contact stresses.

Estimated Mass of Final Design: 4.45 ± 0.05 grams 
* This is 0.025 % of the mass it is supporting!!!

Below is a slow-motion clip of my final design when loaded until failure.  The design failed where I had expected.  This prediction was also confirmed by FEA.