The Design Space
Our redesigned piston must have the same form factor as a McMaster piston to allow for easy descope. Given the team's Fall 2017 semester experience with tie-rod pistons, we elect to continue using this style.
Desired Performance
The piston must be able to supply enough force to break the shear pins with a 4x safety factor before material deformation (this will allow for a smaller, but significant, safety factor on piston use in-flight).
As of 12/27/2017, we plan on using 180lbs of shear pins, making for a desired yield force of 720lbs. This analysis makes use of thin-walled pressure vessel theory, summarized below"
Resources:
The following resources are useful materials for learning about pressure vessel and piston theory:
Jeff Hanson, Texas Tech: Intro to Thin Walled Pressure Vessels
University of Colorado, Boulder: Thin-Walled Pressure Vessel Theory