Advisor: Prof. Kishore Pochiraju Group #10: Biruk Assefa Lazaro Cosma Josh Ottinger Yukinori Sato ME424 Senior Design February 16 th, 2006

2 Agenda Problem Statement Conceptual Design Re-cap Feedback from ME423 Panel Prototype Design Engineering Analysis Fabrication Plan Performance Testing Conclusion

3 Problem Statement ME 423 Re-cap –Design a device to harness wave energy at a remote location –Innovative conceptual design with engineering analysis Goals for ME 424 –Finalize prototype design –Fabricate a working prototype –Test prototype in wave tank –Analyze test data to improve original design

4 Major Issues Original plan to purchase CoTS products –Specifications of components –Scaling factor Optimal design versus fabrication constraints / issues Opening of Davidson Laboratory - scheduled alternative testing facility Optimizing current design with ME budget

5 Conceptual Design Re-cap (ME 423) Full-Wave Rectification Device Buoy – 6ft diameter, 2ft height Reel – Drum diameter 3 inches Shaft – AISI 1045 Steel (1” diameter) Rectifier – 5 gears, 2 unidirectional clutches Gearbox – 180 degree parallel shaft Flywheel – Size determined through testing Alternator – Optimal speed ~ 300 rpm Battery – Deep cycle battery Electronics – Control Alternator EMF Estimated Budget = $ 1915

6 Actions from ME423 Feedback Concerns about excessive mechanical components –Simplified prototype design Alternator efficiency –Typical car alternator efficiency of 50% at 300RPM Ambiguity of drag and natural frequency of the device –Will be determined through testing Water-proofing Device

7 Considerations for Prototype Rectifier –Time and Cost constraint –Replaced with half-wave rectifier –Harvesting more kinetic energy on upstroke –Minimizes required spring torque –Simplicity Less mechanical components Higher reliability and efficiency Scaling –Ease of transportation for testing –Time and Cost constraint

8 Considerations for Prototype Alternator –Low operational RPM preferred –Budget constraints Custom-built Low RPM Alternator ~ $500 Used car alternator (Higher operational RPM range) ~ $10 –Car alternator tested at AutoZone Charging Discharging Diodes

9 Clutch housing Flywheel Reel Gear Box Alternator Prototype Design Wooden base Shaft mounted reel Half-wave rectifier - Unidirectional Clutch Two-stage adjustable gear box Car alternator Batteries Wooden Base

10 Prototype Design Cont. Reel casing Cone shaped hole Buoy Main Casing Scaled Buoy (1:1.5) Diameter = 4ft Height = 1.5 ft Cone shaped hole Allows freedom of cable movement Device centered on top of buoy

11 Gear Box Gear box (gear ratio: 10) Gear box (gear ratio: 20) Two stage gear Box First stage (10 pitch gears): 60 teeth to 15 teeth ( 4:1 gear ratio) Second stage (12 pitch gears): 60 teeth to 24 teeth ( 2.5:1 gear ratio) 60 teeth to 12 teeth ( 5:1 gear ratio) Initially: Two gear ratios (10:1 and 20:1) will be tested Adjustable gear box Design: Input and output shaft immovable Idler shaft will be adjusted to needed position

12 Gear Box Analysis Input Torque & RPM known Primary failure mechanism –Bending Stress of Spur Gear Teeth Utilized Design Modules –Size up gear Face width, pitch, maximum ratio possible for each stage –Factor of Safety of 1.5 –Due to high input torques, Face width of ¾” and greater required

13 Shaft Analysis Shaft Diameter (inches)Max shear stress (Ksi)Max Von - Mises stress (Ksi)Fos (Von - mises)Fos (Shear) 1/271.8 (XZ plane) /836.6 (XZ plane) /421.7 (XZ plane) (XZ plane) Shaft analysis of 5/8” diameter shaft New shaft analysis carried out for modified prototype design Shaft material Chosen: AISI 1566 Steel Reason: Strong and cheap Factor of safety chosen: 2 Max Torque applied: 137 lb-ft 5/8” shaft or greater meet design requirements

14 Electronics Input RPM Low? Charging Voltage > 14.4V? Decrease Rotor EMF Increase Rotor EMF Yes No MICROCONTROLLER LOGIC Relay Battery PWM Alternator Rotor Charging Voltage Rotor Voltage Legend: Signal Current Alternator Stator Encoder RPM Control Rotor (Field) EMF Feedback of RPM and Voltage 3 approaches considered Selected approach: –PWM and relay Encoder and Relay BrainStem GP 1.0 Microcontroller Module BrainStem Charging Voltage Need to figure out this reference RPM

15 Electronics Battery BrainStem 5V Power Source Voltage Divider +- Stator Rotor (Field) Relay Encoder Alternator

16 Technical Specifications Buoy Specifications Buoy diameter 48” and height 18” Buoy material: Urethane foam Reel & Cable Specifications Cable: nylon-coated galvanized steel Total cable travel: 108” Cable diameter: 3/32" Maximum spring recoil strength: 35lbs Reel outer diameter 6” and drum diameter 3.5” Shaft Specifications All shafts sized to withstand the max input cable tension force of 942 lbs Shaft diameters: 1.25”, 1”, 3/4” & 5/8” Clutch Specifications Maximum torque: 133lb-ft Bore diameter: 1.18” (30mm) Gearbox Specifications Two-stages Adjustable gear ratio: 1:10 to 1:20 Maximum input torque: 137 lb-ft Factor Of Safety 1.5 Alternator Specifications Bonneville ’90 automobile alternator Microcontroller Brainstem GP channel, 10 bit A/D 5 digital I/O lines Runs up to 4 programs concurrently Overall System Specifications Estimated device weight: 235lbs Overall Height: 28”

17 Fabrication Plan Important Considerations –Shafts Align to reduce bending and vibrations Machine shafts to fit commercial products –Components must be securely mounted –Waterproof casing 1.18” OD (Machine) 1 1/4” OD 1” OD 3/4” OD 5/8” OD 5/8” OD (Machine) 3/4” OD

18 Fabrication Plan Stationary Mount Connected to Drum Clutch Bearing Stationary mount for spring reel Shaft mounted directly to drum - Allowing torque to be transmitted through device Mounted bearing supplies critical support to the reel Clutch connected to gearbox through custom housing Placement of couplers allows for easy maintenance Alternator mount is set up for simple exchanges of alternator

19 Fabrication Plan Casing is designed to keep all components away from the water except for the reel The reel is encased so it is the only component exposed Sealed lid for easy accessibility

20 Performance Testing Taguchi Method –Orthogonal Array Matrix Optimally perform tests while minimizing runs –Current set-up consists of 4 variables with 3 stages Full scale testing: 81 runs Orthogonal Matrix: 9 runs Experiment Number Variables Wave Height / Wave PeriodAlternator EMFGear RatioFlywheel Size (inches) / (seconds)(Voltage)(ratio)(weight, inertia) 14 / 3A10:1D 24 / 3B15:1E 34 / 3C20:1F 48 / 6A15:1F 58 / 6B20:1D 68 / 6C10:1E 712 / 10A20:1E 812 / 10B10:1F 912 / 10C15:1D Wave Tank Testing –Davidson Laboratory Currently under construction ETOC: April – May 2006 –Webb Institute (Long Island, NY) Scheduled for Mid-April 2006

21 Recording Test Results Variables: –Wave Height –Heave –Input Power Alternator RPM Alternator Torque –Output Power Charging Voltage Charging Current Prototype Test Equipments DAQ LabView Monitor, Record & Analyze PC Data

22 Conclusion Tasks accomplished: –Finalized prototype design –Ordered majority of parts –Workbench in Davidson Laboratory What’s Next: –Order remaining parts –Fabricate buoy –Begin assembly

23 Gantt chart

24 ME 424 Budget