Table of Contents
Team Vision for Detailed Design PhaseTeam NAMASTe planned to complete all assigned deliverables including finalizing the design.
All of the assigned deliverables were successfully completed. In addition, preliminary vacuum testing has been completed in order to verify the validity of the diaphragm concept. A vibration resistant switch has been chosen for the final design. Vibration testing facilities have also been acquired for testing in the second semester. Parts for machining the final design are to be ordered and submitted for completion by the end of the semester.
Progress ReportItems accomplished since last review:
- Began testing different materials for diaphragm
- Have tested silicon, nitrile, and polyethylene
- Silicon and nitrile are looking the most promising
- Thinner material have proven to be ineffective in reliability and and repeatability
- Videos and pictures of testing have been recorded
- Have ordered some thicker materials that we believe will be more appropriate.
- Probable switch has been selected
ITW 16-404 snap action switch 10A @ 28VDC Adheres to MIL-PRF-8805/7 Temperature: -65 to 125 C Vibration: 10-2000Hz Designed mounting brackets
Items to still be accomplished by detailed design review
- Determine switch actuator type: Plunger or lever
- Select final diaphragm material
- Determine final system dimensions/parameters
- Chamber size/materials, diaphragm thickness, diameter, switch location/mounting
- Begin to generate drawing package and bill of materials
Decisions that have been made so far
- We are definitely not going to use 1/64” Nitrile 40A (too thin, 2 diaphragm fractures)
- We would like to go with more of a “rubber-based” material for diaphragm
- Not to use polyethylene due to unpredictability
- We are going to minimize the travel distance that the diaphragm has to deflect in order to gain consistency in repetitions
Beyond the review
- Build complete system
- Determine full system testing plans
- Eliminate potential leaks in system (use aluminum flanges, epoxy, welding?, etc.)
- Look into pressurizing test apparatus to test fast pressure response (i.e. missile vs. vac chamber)
- Provided as .005 G^2/Hz for 20-2000 Hz. Is this assumed to be applied on all axes simultaneously?
Prototyping, Engineering Analysis, Simulation
A prototype was developed in order to characterize a variety of diaphragm materials to determine which material would be the most suitable for our application. The flanges were 3D printed and epoxied onto a chamber constructed from PVC piping. The mounting brackets for the chamber were also 3D printed. The elevation platform was constructed in order to hold the assembly off of the bottom of the vacuum chamber so that the dial indicator could be effectively utilized to determine maximum diaphragm deflection.
Bill of Material (BOM)/Purchasing
Test PlansPressure Deflection Test Questions to be answered by test
- How much deformation do we get from the diaphragm?
- How well does the diaphragm return to its original state?
Questions to be answered by test
- Does vibration play a role in false actuation of the switch
- Does vibration cause deformation in the diaphragm
- If yes to 2, does this change as the chamber becomes pressurized
Testing procedure and administration to be handled by Delphi.
Mechanical drawings of the assembly components can be found in the document linked below.