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Jib Transfer Bench – P13031. Detailed Design Review 3/4/2013 Mike Walsh Nick Davis Charles Kowalyshyn Zeb Koch. Agenda. Project Introduction Review of Customer Needs CAD Model and Subsystem Analysis Calculations System Interfaces Schematics BOM Risk Assessment.
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Jib Transfer Bench – P13031 Detailed Design Review 3/4/2013 Mike Walsh Nick Davis Charles Kowalyshyn Zeb Koch
Agenda • Project Introduction • Review of Customer Needs • CAD Model and Subsystem Analysis • Calculations • System Interfaces • Schematics • BOM • Risk Assessment
Project Introduction • Tasked with creating a device to: • Move a disabled jib trimmer on a Sonar Sailboat from Port to Starboard
Specific Customer Needs • Gary & Zak • No leg mobility / core support • Desires to be fully secured • Cindy • Partial leg & core strength • Desires freedom to exit seat when necessary • Limited footprint available due to P13032’s chair • Cindy needs the option to sail with Gold Medal Chair or as a standalone device • Height differences to consider
Support Bar • Multipurpose Aluminum (Alloy 6061) Rectangular Tube
Seat Bracket Calculations • Assume concentrated load for weight of Seat Bracket at “X” (Center of Gravity) • Free Body Diagram: Tx Ty M Wseat Wseat By Bx
Seat Bracket Calculations Sum the Forces and Moments • ΣFx = 0 = Tx + Bx • ΣFy = 0 = Ty + By – Ws – Wp • ΣM = 0 = M – TxYt–TyXb – Ws(Xws-Xb)- Wp(Xwp- Xb) • 3 equations • 4 unknowns • Mmax=131 ft-lb Tx Yt Yws Ty Ws M Ywp Wp Xb Xws By Xwp Bx
Deriving the 4th Equation • Simulated the bracket as a cantilevered beam • Used Superposition of Table A9 in Shigley’s • Relating Ty to By, Ws, Wp • Sum of deflections due to forces at B = 0 Wseat Wperson M Bx By Tx Ty Yt Xb Xws Xwp
Matlab Function JTB2() - Solves the four equations, with M=131 ft-lb • >> JTB2() • Top Bar X-Force: -32.436667 lbs • Top Bar Y-Force: 152.916899 lbs • Bottom Bar X-Force: 32.436667 lbs • Bottom Bar Y-Force: 123.683101 lbs • Top Bar Total Force: 156.319274 lbs • Bottom Bar Total Force: 127.865737 lbs • Top Bar Deflection: 0.252938 inches • Max Yield Stress : 65300.000000 psi • Top Bar Max Stress : 38214.121245 psi • Pass!-Top Bar • The Stress Factor of Safety is 1.708792
Top Bar Deflection • Maximum Deflection when seat is at center position • Stainless Steel – 1” Diameter • δmax= FL3/(48EI) where I = πr4/4 • Fmax=4σπ/DL Net Force Top Traveler Bar R2 R1
Seat Bracket Stresses • The stresses in the Seat Bracket are very small. • Second moment of inertia is very large • Large C-S area • Assume two beams and check stress in both Tx σ= My/I I=1/12 * b * h3 b= 6.5 inches h=.5 inches y=.25 inches Wp Yt Xwp
Matlab Function JTB2() Seat Bracket- Back • Max Yield Stress : 300.133006 psi Seat Bracket- Bottom • Max Yield Stress : 894.400000 psi
System Interfaces • Generated a list identifying: • All major components • How they interact with one another • (i.e. “foot-bone connected to the leg-bone”) • Possible critical Loads
Purchase System • 3-1 Purchase System Breakdown Lines wrap around to center position Port Starboard Seat Bracket
Bill Of Materials Refer to BOM + Budget doc
Seat Selection • Zak & Gary • Searched dozens of bucket seats • Size and corrosion requirements constrained selection • Settled on RCI High-Back Aluminum Racing Seat with vinyl cover • Relatively cheap • Cindy • Constrained with footprint due to P13032’s chair • Did not find suitable stool on the market • Currently looking into stadium seats
Risk Assessment (Top 5) • 1. Budget • 2. Interfacing with other team’s base plate • 3. Brake – Rotational motion • 4. Handhold Design • 5. Inability to accept user’s cushion due to size constraints
Budget Analysis • Projected: $2,000.00 • Cindy’s System: $2,724.37 • Zak and Gary’s System:$2,915.85 • Not included: • Shipping costs • Machining of aluminum plates • Corrosion testing • Delivery to customer
High Cost Items • Purchase System: $412.50 • 6061 Aluminum: $539.80 • 47% of Budget • Metals (tubes, plates) • BOM has from internet suppliers’ numbers • Looking locally to reduce shipping and price - Klein Steel
Interface (captains chair) • For use with P13032’s Captain’s Chair, the design changes: • Repeated bolt pattern in P13032’s base plate • Less handholds are available • Need Installation procedure when used together
Rotational Motion Braking Mechanism • Currently, the brake for the Lazy Susan is undefined. • Working on several ideas Friction Plate Force-Action Clamp Ratchet & Pawl
Rotation Brake • Curved rubber wedge into Lazy Susan turntable
Handhold Design • Working to improve the previous team’s solution • Working hand-in-hand(hold) with group P13032 to design a standard handhold