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

2. Agenda Team Vision Prototyping Engineering Analysis Simulations
Feasibility
Bill of Materials
Test Plans
Risk Assessment
Action Completion
Plans and Schedule
Individual Three Week Plans
Concerns and Issues

3. Team Vision
The goal of this phase was to create a design and a valid test plan to be used as the guidelines for the final design.
Plans:
Develop 3D models & drawings.
Evaluate feasibility of model
Create test plans
What was done:
Created models for the selected concept – ready to begin prototyping.
Contacted partners for design input and plans for production and decided on manufacturing process.
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. Analysis

7. Feasibility: Prototyping, Analysis and Simulation
Pulley to model shoulder
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
Radius locked on ulna in 3 places using pin locks
Hinge to model elbow joint

8. 3D Model

9. Prototyping 3D Printed Prototype
A model of the system will be 3D printed using PLA filament to assess proper functionality.
(1) First joints will be printed to make sure they work well together
(2) Complete bones will be printed to create a full working model

10. Molding
Once a prototype is completed we will cast the models to create molds, which we can then use to create as many models as needed.
Why?
Time, cost, and material choice.
3D Printing 1 model will take ~20 hours of printing time and cost ~$50 – $60 dollars.
Vacuum molding is ~$5 - $10 per piece and only has to be done once.
Silicone Casting is ~$100 per piece, but only has to be done once.
3D Printing only allows for PLA filament to be used. Casting allows for a wide variety of choices.

11. SME Feedback
Anatomy:
Anatomy of models looks correct and joints selected should work well.
Manufacturing Process:
Begin with printing of only joints to make sure they work as desired to reduce prototyping cost.
Once we make sure model works well print a full working model.
Once we have a good model, then we can cast and create other models.

12. Bill of Materials (BOM)

13. Test Plans – Engineering Requirements Overview

14. Test Plans ER1,3,5 – Static Force of Muscle A, B, and C.
Test - Attach load cell to break in muscle string, hang 250kg 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.
ER 2,4,6 – Dynamic Force of Muscle A, B, and C.
Test - Attach load cell to break in muscle string, hang 250kg mass from hand hook, allow arm to rotate and fall with weight, then get the peak force value through Capstone.
ER7 – 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.

15. Test Plans
 ER8 – Max Load
Test -Hang a load of 500kg 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.
ER9- 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.
ER10,11 – Deviation and Possible Positions
Test - Set the model in each possible position with the 250kg 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.

16. Test Plans ER12- Time Required for Assembly
ER12- 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 250kg weight from the hand hook upon completion.
ER14- Final Size of Model
Test -Measure the dimensions of the final model, upright, holding no weight and the elbow in such a way that the elbow is flexed and the lower arm does not extend past the base of the model. Strings may be loosened or untied to best minimize size of model.
Validity – The base of the device must be within 2ft by 2 ft.

17. Risk Assessment

18. Action Completion Systems Design
Update/Verify prototype:
Model joints & bones: bones completed (100%) joint styles need determining (50%)
Consider options/model joints attachments: 50%
Prototype Joints, places of movement:
Begin planning possible verifying tests/procedures: 100%
Update flow diagrams: 100%
Drawings of design plans, prototype: Drawings & plans (100%), no second prototype developed in this period due to modeling being primary focus (25%)
Update risk factors: 100%
Identify required factors/ ideal conditions for successful use: 100%
Plan risk responses & solutions: 100%
Order toughest problems moving forward: 100%
Outline resources or methods for solutions: 100%
Run pre-lim. test on prototype/ Test independent systems if possible:

19. Plans & Schedule Project Plan Highlights
Prepare for printing, casting, prototyping
Address remaining modeling and design needs
Ensure models will function and are printable

20. Individual Three Week Plan
Amanda:
Actively participate in the building of a prototype model (12 hours, ongoing)
Review and edit the 3-D CAD modeling of the humerus, radius, and ulna and determine (10 hours, Week 12&13).
Participate with team on finalizing a decision on modeling or printing (2 hours, Week 11).
Consult with RIT athletic trainers throughout the modeling to ensure proper anatomy of bones and “muscles” (4 hours, ongoing)
Update the bill of materials that is needed to fully complete the elbow model (2 hours, Week 12)
Shannon:
Communicate with local printers (on/off campus) about material options and printing/casting timeline (3 hours Week 12)
Assemble initial prototype (3 hours, Week 13)
Ensure all necessary equipment to test plan verification is available (3 hours, Week 12).
Apply new test plans to prototype and/or available systems (5 hours Week 13)

21. Individual Three Week Plan
Chris:
Continue modeling of bones and complete system in Solidworks (10 hours)
Research specific parts that we will need to buy (5 hours)
Research additional 3d cad methods for creating bones (5 to 10 hours)
Finish the static analysis of the 3 force system, consult a professor (5 hours)
Research materials to build the bones out of. (3 to 5 hours)
Maria:
Communicate with Mike – the construct - and other 3D printing companies about material options and time/cost for model manufacturing and prototyping. (ongoing)
Assist in assembling of prototypes (3 hours, Week 13)
Communicate with SMEs to get input on prototype. (ongoing)
Participate in testing of prototypes (ongoing)
Communicate with customer about prototypes and possible issues. (ongoing)

22. Concerns and Issues Frictional losses of the string through the bones
Use of molding versus 3-D printing parts (product strength)
Anatomically accurately modeling the joint connections

23. Questions?