P16080: Heart Pump

Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

By the end of MSD I the team hoped to:

To see all any and all documents associated with this cycle, see the Detailed Design Documents repository.

Prototyping, Engineering Analysis, Simulation

Diaphragm Selection

Initially, two inexpensive different types of air brake diaphragms were purchased to test for characteristics and design feasibility. Unfortunately, the diaphragms purchased were too large and rigid for the current design's use, as they are used in large industrial air brake applications. This was where the current design's inspiration came from (see PDD Critical Design Change).

First puchrased brake diaphragms

First puchrased brake diaphragms

Based off this knowledge, the team hoped to find a diaphragm better suited for the current design. This was based off of the following requirements:

  1. Outputs required stroke volume (derived from human physiology & Engineering Requirements)
  2. Withstands operational pressures
  3. Very minor resistance due to movement of diaphragm
  4. Waterproof
  5. Easily compatible with spring piston design

After looking at multiple designs, it was the third point on this list that led the team to DiaCom's design for diaphragms, which are used in a wide array of industries. The diaphragms design (pictured below) uses edges that fold over on themselves to allow the diaphragm to "roll" as it moves up and down, which creates virtually no resistance to motion. The diaphragms are often fitted with springs or pistons, which fit well with the current design. Ultimately the team chose to use diaphragm F-475-187.

DaiCom Diaphragm Schematic Selected Type F Diaphragm
public/Photo Gallery/Parts/DiaComTheory.PNG public/Photo Gallery/Parts/TypeFDiaphragm.jpg

Pressure Analysis Updates

Once the diaphragm design was selected, a final Hydraulic Analysis could be conducted to understand the relationship between pneumatic air pressure, and required hydraulic pressure increase. Using diaphragm geometry, a free body diagram, and the simple relationship that Pressure = Force divided by Area, a formula was created that can calculate pneumatic pressure as a function of:

To see a full analysis for how these equations were derived, see the Hydraulic Calculations PDF located on EDGE.

This equation was then integrated into the PDD hydraulic calculation spreadsheet, where previously derived values could be plugged into the equations to calculate pneumatic pressures under different circumstances. This spreadsheet was also helpful for experimenting with different k values of the spring, allowing one to observe the affect of a changing spring constant on required pneumatic air pressure.

Chamber Schematic Pneumatics tab screenshot
public/Detailed Design Documents/HydraulicCalculationsSchematic.PNG public/Detailed Design Documents/HydraulicCalculations_R2.PNG

Click here for a link to the live Hydraulic Calculations xlsx document.

CAD Model Updates

Major updates to the CAD model included:

Screen shots of CAD:

New chamber - full view Exploded view of Chamber
public/Photo Gallery/3D Model/R3_ChamberD.PNG public/Photo Gallery/3D Model/R3_ChamberExplodedB.PNG
Exploded view of diaphragm piston assembly

Exploded view of diaphragm piston assembly

To see all screen shots, see the Photo Gallery. To view ALL CAD files, see our Detailed Design Documents CAD Repository.

Drawings, Schematics, & Flow Charts

LabView Flow Charts & Transfer Functions

The data aquisition flow chart was updated since last cycle, created the following:
Updated data aqusition flow chart, revision #3

Updated data aqusition flow chart, revision #3

Transfer functions & algebraic relationships for the system were also derived during this cycle, specifically for pressure and flow rate, respectively. Below are the following formulas:

Transfer function for Pressure

Transfer function for Pressure

Flow rate formula

Flow rate formula

Assembly Drawings

Hydraulic End Cap Pneumatic End Cap
public/Detailed Design Documents/CAD/R3/Drawings/HydraulicEndCap.png public/Detailed Design Documents/CAD/R3/Drawings/PneumaticEndCap.png

To see assembly drawings for the current CAD model, see the "Drawings" folder

Bill of Material (BOM)

Several parts were updated from our last cycle, as major design parameters were finalized, allowing final selection for almost every item listed on the final BOM:

Bill of Materials, Revision #4 (Final BOM for MSD I)

Bill of Materials, Revision #4 (Final BOM for MSD I)

See a link to the live Excel document here

Test Plans

Test plans were updated and refined during the DDR cycle. Several detailed test plans were also created. The entire list of test plans was tabulated into a spreadsheet:

Revisions to test plans since last cycle

Revisions to test plans since last cycle

See the live Excel Document here

Detailed Test Plans

Detailed test plans to be completed:

Detailed Test Plans (Results)

Risk Assessment

Risk management, revision #5

Risk management, revision #5

See a link to the more in depth, live Excel document here

Some notable mitigation plans that were put in place this cycle:

Design Review Materials

Too see the PDF of this cycles design review presentation, Please click here.

Engineering Requirements

Current engineering requirements, revision number 6

Current engineering requirements, revision number 6

See a link to the live excel documentHERE

Meeting Minutes

Plans for next phase

Gantt Chart from now, MSDI, untill the beginning of MSD II

Gantt Chart from now, MSDI, untill the beginning of MSD II

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