P18352: Sandia Passive Vacuum Detection Team B
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Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

During this Phase the team plans on continuing the design laid out in the previous phase. The Feasibility needs to be completed which will confirm on paper that this system will work. In addition prototyping of the diaphragm material will be started to confirm that the material being used will work in our situation.

During this phase, the team learned about the feasibility of our design. We used Solidworks finite element analysis to model the diaphragm and determine a suitable diameter and operating pressure. In addition we ran hand calculations to determine a magnet needed to complete the design. The team received free samples of Kapton material and ordered magnets for testing.

Prototyping, Engineering Analysis, Simulation

The Team has used engineering software including SolidWorks to develop a Finite Element Analysis simulation of the diaphragm. This is important because it tells us where the greatest stresses are on the diaphragm and helps to better design the system.

For the Magnets, the team has worked to determine a size and strength magnet that will be needed to hold the system in place. This was determined using data from a magnet supplier.

Magnet Force vs Distance

Magnet Force vs Distance

The modeling takes into effect the use cases of the pressure sensor, in which it will either reach the desired pressure and activate the switch, or not activate if the desired pressure is never reached.

Feasibility: Prototyping, Analysis, Simulation

Initially, we were using National Lab's thin plate theory to determine how the diaphragm would act during operation, but this approach didn't characterize enough of the motion of the diaphragm during operation so we instead used simulation to understand the operating conditions of our diaphragm. Using the simulation available in SolidWorks we ran a Finite Element Analysis (FEA) on our diaphragm to better understand how the diaphragm would act in test conditions as well as providing us with additional information compared to thin plate theory calculations.

Below is the FEA result of the simulation run with a 3/4" in diameter diaphragm.

3/4

3/4" FEA deformation results

Below is a table of max center deflection for various diaphragm diameters

Diameter (in) Max deflection (in)
0.50 0.020
0.75 0.034
1.00 0.050
1.25 0.068

To do initial testing for diaphragms we assembled a test setup (see below) to pressurize one side of the diaphragm to simulate operating conditions.

Test setup

Test setup

The pressure gauge and regulator combo allowed us to have more control over the pressurizing of the diaphragm.

Sample housing

Sample housing

This sample housing for the test setup allows us to test various diaphragm materials quickly since there is easy access to the diaphragm.

Drawings, Schematics, Flow Charts, Simulations

Diaphragms of 0.5

Diaphragms of 0.5", 0.75", 1", and 1.25" were simulated

K&J Magnetics Magnet D9C

K&J Magnetics Magnet D9C

Bill of Materials (BOM)

Bill of Materials

Bill of Materials

Bill of Materials

Test Plans

The switch will be tested in the Hitachi HUS-5GB High Vacuum Evaporator. The manual for the evaporator and the inspection/safety/testing documents procedures are contained in the files below:

Hitachi HUS-5GB High Vacuum Evaporator Manual

Inspection, Safety, and Testing Procedure

Design and Flowcharts

Preliminary Detailed Design

Preliminary Detailed Design

Risk Assessment

Project Risks

Project Risks

Design Review Materials

Detailed Design Review Presentation

Plans for next phase

By the next review our plan is to bring forth a completed design with proof of concept, prototype analysis and relevant data that will be fabricated during Senior Design 2. We will have a BOM stating all the parts for purchase, drawings created, and test plans for how to properly test the system.


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