advisor: prof. kishore pochiraju group #10: biruk assefa lazaro cosma josh ottinger yukinori sato...
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Advisor: Prof. Kishore Pochiraju
Group #10:Biruk Assefa
Lazaro Cosma
Josh Ottinger
Yukinori Sato
ME424 Senior Design
February 16th, 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 housingFlywheel
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
Design Equation forBending of Spur Gear Teeth
Given information that is common to both gears in the set: = 14.5 degrees Pressure angle P d = 12 teeth/in Diametral pitchF = 0.75 inches Face width Wt = 176.4 lbf Transmitted load
v t = 288 ft/min Pitch line velocity
SF = 1.50 Factor of safety
Given information that may be different for each gear in the set: Pinion Gear
N i = 60 24 teeth Number of teethMaterial = 1018 Steel 1018 Steel Material type
Values found from the above information and inserted by the designer:s at = 50,000 50,000 psi Allowable stressJ = 0.42 0.39 Geometry factor
Values computed using the above information:K v = 1.23 Dynamic factorK m = 2.3 Load distribution factors t = 18,869 20,321 psi Left-hand side of eqn.
RHS 33,333 33,333 psi Right-hand side of eqn.
Status SAFE SAFE
RTF
NatBmdsvot KKS
Ys
J
KK
F
PKKKW
13
Shaft Analysis
Shaft Diameter (inches)
Max shear stress (Ksi)
Max Von - Mises stress (Ksi) Fos (Von - mises) Fos (Shear)
1/2 71.8 (XZ plane) 125 2 1.7
5/8 36.6 (XZ plane) 66.2 3.8 3.3
3/4 21.7 (XZ plane) 38.1 6.6 5.7
1 9.5 (XZ plane) 16.5 15 13
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
Yes
No
No
MICROCONTROLLER LOGIC
Relay
Battery
PWM AlternatorRotor
Charging Voltage
Rotor Voltage
Legend: Signal Current
AlternatorStator
Encoder
RPM
• Control Rotor (Field) EMF• Feedback of RPM and Voltage• 3 approaches considered• Selected approach:
– PWM and relay
• Encoder and RelayBrainStem GP 1.0
Microcontroller Module
BrainStem
Charging Voltage
Need to figure out this reference RPM
15
Electronics
BatteryBrainStem
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 foamReel & 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 1.5Alternator Specifications• Bonneville ’90 automobile alternatorMicrocontroller• Brainstem GP 1.0• 5 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” OD1” 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 Period Alternator EMF Gear Ratio Flywheel Size
(inches) / (seconds) (Voltage) (ratio) (weight, inertia)
1 4 / 3 A 10:1 D
2 4 / 3 B 15:1 E
3 4 / 3 C 20:1 F
4 8 / 6 A 15:1 F
5 8 / 6 B 20:1 D
6 8 / 6 C 10:1 E
7 12 / 10 A 20:1 E
8 12 / 10 B 10:1 F
9 12 / 10 C 15:1 D
• 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
LabViewMonitor, 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
Part Name Description Quantity Total CostReelShaft Mount Reel Spring Loaded Reel 1 $ 110.58
GearsInput Gear 10 Pitch, 1" face, 60 Teeth 1144 Steel 1 $ 50.06 Idler Gear_1 10 Pitch, 1" face, 15 Teeth 1144 Steel 1 $ 20.62 Idler Gear_2 12 Pitch, 3/4" face, 60 Teeth 1144 Steel 1 $ 51.53 Output Gear_1 12 Pitch, 3/4" face, 24 Teeth 1144 Steel 1 $ 24.79 Output Gear_2 12 Pitch, 3/4" face, 12 Teeth 1144 Steel 1 $ 13.06
Shafts1.25" OD 12" in length, 1566 Steel 1 $ 22.00 1" OD 18" in length, 1566 Steel 1 $ 25.20 3/4" OD 36" in length, 1566 Steel 1 $ 36.31 5/8" OD 12" in length, 1566 Steel 1 $ 9.78 7/16" x 7/16" 12" in length, High Carbon Steel: Standard 1 $ 9.99
One-way ClutchCSK 30 Sprag clutch w/ 6200 series ball bearing Torque rating: 133 ft.lbs 1 $ 70.00
Mounts1 1/4"OD Base Aluminum Base Mounted Self-Lubricating Bronze Sleeve Bearings 1 $ 29.64 3/4"OD Base Aluminum Base Mounted Self-Lubricating Bronze Sleeve Bearings 1 $ 12.96 1"OD Flange Stamped steel Flange Mounted Ball Bearings 1 $ 12.77 3/4"OD Flange Stamped steel Flange Mounted Ball Bearings 2 $ 23.80 5/8"OD Flange Stamped steel Flange Mounted Ball Bearings 1 $ 11.33
CouplerSet Screw Coupler Steel One-Piece Set-Screw Coupling 3/4" Bore, 1-1/2" Od, 2" Length 1 $ 10.62 Set Screw Coupler Steel One-Piece Set-Screw Coupling 5/8" Bore, 1-1/4" Od, 2" Length 1 $ 9.39
BuoyUrethane Foam 1 $ -
CasingHDPE sheets High Density Polyethylene (HDPE) Sheet 1/4" Thick, 48" X 48" 2 $ 86.26
ElectronicsMicrocontroller Brainstem GP 1.0 1 -$ Serial Interface Connector Connects microcontroller to a PC 1 11.75$ Relay 12VDC/30A, solenoid 1 6.29$
Total $658.73
ME 424 Budget