DP-2 Final DeliveRABLES
3d Printed Prototype
Here you can see various photos of the prototype and supporting documentation:
Magnetic Research Takeaways (click the bulleted text for sources):
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Same poles of magnets will repel when interacting
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The attractive/ repulsive forces of magnets decrease rapidly with increasing distance
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If magnets are stacked with the height approximately half as high as the diameter of each individual disc magnet then the force will multiply with each additional magnet
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The repulsive interaction of a very strong magnet and weak magnet in close proximity can result in the reversal of the small magnet's polarity and ultimately attraction
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Rare earth magnets like ones made of neodymium boron iron are amongst the strongest permanent magnets in the world
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"It is estimated that a neodymium magnet loses approximately 5% of its magnetism every 100 years"
Considering the logistics of the magnetic suspension aspect of this design, I completed a great deal of research and calculations (see below) to see if it was feasible. I determined that we would need upwards of 50 (25 stacked pairs) D51-N52 grade magnets of diameter 5/16" and thickness 1/16" to support the patient's body weight. Considering that the force on the hip joint can be upwards of 5 times body weight when walking many more magnets would need to implement. With the current design, there is not enough surface area on the interior of the cup to support the required number of magnets. As a result, this design will not create a completely frictionless joint as intended but will still effectively reduce the amount of released wear particles by decreasing the normal force between the surfaces.
All in all, as of now, the magnetic technology is not where it needs to be to create a completely frictionless joint that will support many times someone's body weight.
Poster Presentation
Here you can see various photos of the poster board along with a digital document containing all of the text and figures in a logical order.
Overview
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Left Panel - Patient Information, Design & Method of Surgical Implantation
Middle Panel - Title, Key Points, X-rays, Prototype, CAD Assembly & Justification
Right Panel - Materials & References
Python Program
Click here to download a copy of the code, whose output is shown below:
[evaluate Team13_PythonProgram.py]
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Welcome to Team 13's Hip Implant Calculation Program!
This program performs 3 different functions:
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1. Calculate the minimal allowable implant stem diameter
2. Calculate the fatigue life for a metal implant
3. Calculate the number of years post-implantation before there is risk of femoral fracture
Please enter the number corresponding to the option you are interested in.
To exit the program, enter any other character: 1
Body Weight: 784.8 N
Canal Diameter: 18 mm
Ultimate Tensile Strength: 853 MPa
Minimum Stem Diameter: 14.95 mm
Applied Tensile Stress: 853.0 MPa
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1. Calculate the minimal allowable implant stem diameter
2. Calculate the fatigue life for a metal implant
3. Calculate the number of years post-implantation before there is risk of femoral fracture
Please enter the number corresponding to the option you are interested in.
To exit the program, enter any other character: 2
The selected material will not fail due to fatigue for the provided data.
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1. Calculate the minimal allowable implant stem diameter
2. Calculate the fatigue life for a metal implant
3. Calculate the number of years post-implantation before there is risk of femoral fracture
Please enter the number corresponding to the option you are interested in.
To exit the program, enter any other character: 3
The implant will fail after 34 years.
The compressive stress that will cause failure is 28.77 MPa.
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1. Calculate the minimal allowable implant stem diameter
2. Calculate the fatigue life for a metal implant
3. Calculate the number of years post-implantation before there is risk of femoral fracture
Please enter the number corresponding to the option you are interested in.
To exit the program, enter any other character: done
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Thank you for using our program!
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