1. P17082 Biomechanical Elbow Model Detailed Design
Maria Romero-Creel, Shannon Keenan, Chris Harley, Amanda Cook

2. Agenda Team Vision Benchmarking Prototyping Manufacturing Processes
Bill of Materials
Test Plans
Risk Assessment
Action Completion
Plans and Schedule
Individual Three Week Plans
Concerns and Issues

3. Team Vision
The goals of this phase and design review were to have bone designs appropriate for a functional prototype and decide on the production methods for the model.
Plans:
Correct previous 3D models & drawings.
3D Print Working Prototype
Update Testing Plans
What was done:
3 different prototypes were 3D printed in different sizes and densities
Assessed various possible methods of production of completed models.
Evaluated the engineering requirements, test plans, risks, and costs of the designed system.
Determined challenges of the design, how successful designs and subsystems will be evaluated, and identifying sources and triggers for risk mitigation.

4. Functional Decomposition

5. Benchmarking - Updated

6. Prototyping – Preliminary Detailed Design
A model of the system will be 3D printed using PLA filament to assess proper functionality.
Primary Design
Radius
Length
 23.2 cm
Shape
Approximated with 3D printed model
Max strain
1 cm
Ulna
 25.15 cm
Humerus
 32.05 cm
Muscles
Force
Can be modeled with string as a force
Attachment Points
Can be printed into the bone for reputably accurate models

7. First Prototype Scaled : 1/3 of the real size PLA Filament
What was right? - Length of bones was accurate.
What was wrong? - Joints didn’t match perfectly. - Spacers for goniometer were missing. - Guide channel for string on top of humerus was needed. - Not strong enough. - Printed using small 3D printer (resolution not accurate)

8. Second Prototype Scaled : 1/3 of the real size PLA Filament
What was right? - Joints fit better. - Spacers were appropriate for desired use - Guide channel on humerus printed well.
What was wrong? - Size. - Missing holes for strings to go through

9. Final Prototype – Part Models

10. Final Prototype Real Size
PETG Filament  Better resolution using Gigabot
What was right? - Joints fit well. - Spacers were appropriate for desired use - Resolution was good. - Easy to melt holes into model. - Fits well with PASCO stand.
Concerns - Strength of the bones. - Complexity of model for manufacturing.

11. Casting vs. 3D Printing Casting 3D Printing Pros: Better resolution
High initial cost, but low cost after casts are done
Better strength of material
Cons:
Cost of molds
Difficult with complex models
3D Printing
Pros:
Low cost
Easy Access to Construct
Can continue to be modified throughout.
Cons:
Lower resolution
Longer lead time
Strength Concerns

12. Assessing Strength of 3D Printing Parts
Printing using different densities

13. Bill of Materials (BOM)

14. Test Plans – Engineering Requirements Overview

15. Test Plans ER1,2,3 – Static Force of Muscle A, B, and C.
Test - Attach load cell to break in muscle string, hang 250g mass from hand hook, wait for arm to lower under the weight and settle, then get read out from Capstone.
Validity- Force achieved at rest must match accepted anatomical value.
ER4 – Angles at each position
Test - With each muscle attached and load cells strung, and the goniometer attached and reading out to Capstone, the arm is bent at the elbow and moved through the available range of motion.
Validity- readout must show that the arm can move from approximately 0o and 180o.
  ER5 – Max Load
Test -Hang a load of 500g from the hand hook while holding the lower arm up to the upper arm so that the angle of the elbow is approximately 0­o. release the lower arm and allow the weight and lower arm to fall.
Validity- The arm must be able to fall and stop while still holding the weight, staying upright and stable and produce steady force and angle change graphs / tables through Capstone. There should be no bending or material failure in a valid case, and the entire base must still be resting on the tabletop.

16. Test Plans ER6- Muscle Attachment Position
Test - With load cells in place, no weights, and the lower arm resting so that the angle of the elbow is approximately 90o, measure the angles of the muscles with the bones and the distance of the muscle attachment to the bones.
Validity – Both values must be within ±5%of the average adult.
ER7,8 – Deviation and Possible Positions
Test - Set the model in each possible position with the 250g weight. For each position (supinated wrist, pronated wrist, flexed elbow), allow the device to sit, with no contact or extra support from an outside object for 1 minute, measure deviation.
Validity – The position set by the user must not deviate by more than ±1cm during the wait period.
ER9- Time Required for Assembly
Test - Begin with an unassembled device. Start a timer and begin assembly, including the addition of base structure strings, load cells, goniometer, and arm straps. Include all hardware cables necessary for data acquisition (load cells, goniometer).
Validity – The full assembly takes approximately 20 minutes or less to assemble and can support a 250g weight from the hand hook upon completion.

17. Risk Assessment

18. Action Completion Systems Design
Action Item Progress
Finish Solidworks models of the bones and joints – 100%
Print multiple revisions of bones and joints at various scales for updating the models and visualizing any potential issues, ending with the prototype prints from the final models – 100%
Communicate with the RIT for prints & design input – 100%
Make manual edits to bones and joints – 80%
Investigate casting materials & options – 80%
Obtain base for structure stand – 100%
Update Bill of materials – 100%
Update Engineering Requirements – 100%
Update Risk Assessment – 100%
Update drawings – 100%
Update Test Plans – 100%
Address immediate purchasing needs – 100%
Test ‘muscle’ fit – 50%
Assembly – 80%

19. Individual Contributions
Print revisions of bones at multiple scales – All
Consider placement of goniometer and force gauges for data acquisition - All
Make adjustments to Solidworks bone and joint models – Chris & Amanda
Communicate with the RIT - Maria
Make manual edits to bones and joints – All
Investigate casting materials & options – Maria
Obtain base for structure stand – Amanda
Update Bill of materials – Amanda
Update Engineering Requirements – Shannon
Update Risk Assessment – Chris
Update drawings - Chris & Amanda
Update Test Plans – Shannon
Test ‘muscle’ fit – All
Address immediate purchasing needs – Amanda
Assembly - All

20. Plans & Schedule Project Plan Highlights1
Project Plan Highlights
Printing bones using a higher density.
Assemble model.
Apply test plans on prototype.

21. Individual Three Week Plan
Amanda:
Purchasing / Budget
Remain active in test plans
3D CAD Models – Ensure accuracy and help update models
Continue to consult with SME to ensure physiological accuracy of model.
Shannon:
Run test plans on preliminary prototype (3 hours, Week 1)
Recreate and address any concerns with base subsystems (3 hours, Week 1)
Begin printing next set of bones at full density (5 hours, Weeks 2)
Add muscle subsystems to prototype (2 hours, Week 2)

22. Individual Three Week Plan
Chris:
Finish the final tweaks to the cad models of the bones. (1 hour)
Assess our prototype and see if there are any last-minute changes that seem necessary (3 hours)
Ensure that all materials are ordered and finalized (2 hours)
Do mock labs with the prototype and stress test the prototype. (5 – 6 hours)
Test the full-strength parts during the first week of MSD II (5 hours)
Maria:
Consult SMEs and Customer and decide on casting vs. 3D printing.
Participate in testing of prototype.
Participate in building and assessing feasibility of model.
Consult SMEs and help ensure physiological accuracy of model.

23. Concerns and Issues Hinge Concerns
Budget – Depending on casting or 3D printing
Strength of bones – Material

24. Questions or Suggestions?