156B Week 8

Overview of Status of Analysis, Design, Fabrication, Tests, etc.

• • 3 Newly fabricated anchors with new flexure hinge design

    • Had 4, but first iteration broke during EDM

    • Currently have ~5 more waiting for EDM

  • 3D printed inserter cone tip to expedite manufacturing process

    • Still intend to make Titanium tips

  • Shipment arrived this morning of 2 more Titanium rods so we can make more anchors

    • More rods → less waiting

  • Shipment of Steel Wire for testing arrived with the Titanium rods

  • Literature review of Flexure hinges

    • Found text book for free through Library: “Compliant Mechanisms Design of Flexure Hinges.”

    • Had specific section of the book for Large Displacement scenario

  • FEA produced results stress distributions for different ranges of deployment

    • Undeployed state → 42N reached before fracturing levels reached in hinge

    • Mid-Deployment → 30N

  • Meeting scheduled with Surgeon for this Friday

Accomplishments from Previous Week

• • Have 3 prototypes made from titanium, ~8 by end of day

  • FEA

  • Flexure Hinge review for large displacements

  • Sawbones is prepped for anchor insertion

Goals for Next Week (list names after each item). Use specific and measurable objectives

• • Start testing today on the Instron Machine, continue testing into next week

  • Potentially make fine tuning alterations to design after testing

  • Create step by step deployment images animated and real

Sponsor Comments from Last Meeting and Actions Taken to Address these Comments

• • Does flexure hinge tend to break on the Tension side or the compression side?

  • Locking mechanism for anchor to tip piece

Instructor Comments from Last Meeting and Actions Taken to Address these Comments

• • Do more research on flexure hinges

    • Large deformation is too complex for a closed form solution

    • Compares to a cantilever beam

  • Do a simulation or hand calculations

    • Simulation was ran

  • Should meet with surgeon again (Anshu)

    • Compiled questions

    • Scheduled meeting

Risks and Areas of Concern

• • Learned how to mill side notches

    • Still dependent on Ian to EDM

  • Dimensioning and scaling of anchor

    • Product specs of anchors that are posted online may not be accurate.

    • Assembling another list of questions for our surgical consult

  • Wing deployment in simulated bone

    • May need a lot of force to open

Resources or Information Required but not Available

• • Porosity size of bone

    • Meeting with surgeon and testing with multiple porosities

  • Type of drilled hole for soft anchors (clearance or smaller hole where they shove in the inserter?)

    • Will be included in previously mentioned list of questions for surgeon

Schedule

• • Continue to manufacture anchors out of titanium

  • Work on poster and report

  • Test in Sawbones this week

  • Will meet with surgeon to discuss design

Budget (list amount spent and amount remaining)

• • $284.72 spent

  • $815.28 remaining

Progress on Report and Webpage

• • Visuals added to webpage