19
Engineering Analysis Presentation Presentation ME 4182 ME 4182 Team: 5 Guys Engineering + 1 Nathan Bessette, Rahul Bhatia, Andrew Cass, Zeeshan Saiyed Zeeshan Saiyed, Glen Stewart YJ Chok
Engineering Analysis PresentationPresentation
ME 4182ME 4182Team: 5 Guys Engineering + 1
Nathan Bessette, Rahul Bhatia, Andrew Cass,
Zeeshan SaiyedZeeshan Saiyed, Glen Stewart
YJ ChokJ C o
Automatic Whiteboard WiperAutomatic Whiteboard Wiper
• Last TimeLast Time– Layout Drawings
• Layout or assembly drawings– How individual parts or subsystems fit together as a whole
• Encouraged to use computer modeling software• Drawings for actual design, not prototype
• This Time– Present a critical analysis of the design– Determine the areas that are most likely to fail – Potential engineering and/or manufacturing problems
CalculationsCalculations
Using the situation with the heavy writing
5”
2”
For 9.6 erasers to span the height of the board
For 4 8 erasers to span half the height of the boardFor 4.8 erasers to span half the height of the board
Material AnalysisMaterial AnalysisWeight Density
Mass Density
Yield Stress
Ultimate Stress
Modulus of
ElasticityApproximate
DeflectionDensity [lb/ft3]
Density [slugs/ft3]
Stress [ksi]
Stress [ksi]
Elasticity E
[ksi]
Deflection [in]
D =L3 •W
Aluminum 170 5.3 40 45 10000 0.0032D
48• E • I
High Strength Steel 490 15.2 100 130 29000 0.0011
Deflection Analysis For Vertical Slider BarA Ci l
Stainless Steel 490 15.2 70 105 29000 0.0011-Assume Circular cross section-5 ft. longHalf the normal force
Polyethylene 75 2.35 N/A 2.5 150 0.2101-Half the normal force from the board acts at the center of the rod (5.5 lbs)
Eraser sub-assembly Weight Calculation
Eraser Subassembly Weight CalculationEraser Subassembly Weight Calculation
• Density: ρ = 0.5097 lbs. / Ft. of bar• Quantity of bar
2 x 60” bars = 120”4 x 5” supports = 20”4 x 5 supports 201 x (2” x 24”) eraser backing = 48”TOTAL = 15⅔ ft
Al i W i h 15⅔ f 0 5097 lb / F 8 lb• Aluminum Weight = 15⅔ ft · 0.5097 lbs. / Ft. ≈ 8 lbs.• Motor Assembly
Motor ≈ 2.3 lbRack & Pinion ≈ 1 lbExtras ≈ 0.5 lb
• Motor Assembly Weight ≈ 3 8 lbs• Motor Assembly Weight ≈ 3.8 lbs.• TOTAL WEIGHT, W ≈ 11.8 lbs.
Statics Analysis (Eraser at bottom)Statics Analysis (Eraser at bottom)• Forces on A and B are reactions on Sliding Assembly
from sliding railsfrom sliding rails.– Total of two sliding rails attached together
• Weight acts at the center of gravity (3.85 inches from the wall, 2.75 feet from the bottom of the assembly)
• Normal force from board N is 11 lbs and acts at the• Normal force from board, Nx is 11 lbs and acts at the center of the eraser (1.5 feet from the bottom of the assembly)
• Reactions calculated by summing forces and summing moments about a fixed pointmoments about a fixed point
∑MB = 0 = (Ax × 5 ft) − (Nx ×1.5 ft) − (W ×3.8512
ft)
∑Fx = 0 = Nx − Ax − Bx∑Fy = 0 = Ay + By −W
B x x 12
Reaction Value (lbs)
Ax 2.03
B 3 47Bx 3.47
Ay 2.95
By 2.95
Statics Analysis (Eraser at Top)Statics Analysis (Eraser at Top)• Forces on A and B are reactions on Sliding Assembly
from sliding railsfrom sliding rails.– Total of two sliding rails attached together
• Weight acts at the center of gravity (3.85 inches from the wall, 1.90 feet from the bottom of the assembly)
• Normal force from board N is 11 lbs and acts at the• Normal force from board, Nx is 11 lbs and acts at the center of the eraser (3.5 feet from the bottom of the assembly)
• Reactions calculated by summing forces and summing moments about a fixed pointmoments about a fixed point
∑Fy = 0 = Ay + By −W∑Fx = 0 = Nx − Ax − Bx∑MB = 0 = (Ax × 5 ft) − (Nx ×1.5 ft) − (W ×
3.8512
ft)
Reaction Value (lbs)
Ax 4.23
B 1 27
12
Bx 1.27
Ay 2.95
By 2.95
Possible points of failurePossible points of failure
Shear Analysis on the wheelsFront View Side View
Wheels
Track
Wheel SupportSupport Attachment
Top View Area of the wheels under shear
Shear stress on the wheels due to weight
Area of one wheel under shear, Aw = 0.1266 in2
Total Area under shear, A T,w = 0.5063 in2
Sh t d t N l f F / A 5 825 iShear stress due to Normal force, τN = Fs,W / A T,w = 5.825 psi Shear strength of Nylatron, Sy = 10,500 psi
Factor of safety for the wheels, n = 1803
Fs,N = 2.950 lb
Area of the wheels under shear
Shear stress on the wheels due to Normal Force
Area of one wheel under shear, As = 0.0765 in2
Total Area under shear, A T,s = 0.3061 in2
Sh t d t N l f F / A 13 816 i
F 4 229 lb
Shear stress due to Normal force, τN = Fs,N/ A T,s = 13.816 psi Shear strength of Nylatron, Sy = 10,500 psi
Factor of safety for the wheels, n = 760
Fs,N = 4.229 lb
Area of the wheels under shear
Horizontal Torque RequirementsHorizontal Torque Requirements
• Required Torque calculation:Required Torque calculation:T = Fmax tension due to friction·rpulley
( lb )(2 2 i )
4.5” ID Pulley
= (7 lbs.)(2.25 in.)= 15.75 lb-in
T = 2 6 lb ft
= 1.3 lb-ftTreq = 2.6 lb‐ft
Motor
Treq = 1.3 lb-ft minimumFmax, tension = 7 lbs.
Vertical Torque RequirementsVertical Torque Requirements
• Required Torque calculation:Required Torque calculation:T = Fmax(friction+weight)·rgear
(12 lb )(1 8 i )= (12 lbs.)(1.875 in.)= 22.5 lb-in
Ffriction = 7 lbs.
= 1.875 lb-ftMotor3.75” ID Gear
Treq = 1.875 lb-ft minimumFweight = 5 lbs.
F Weight of MotorFweight = Weight of Motor Assembly (3 lb est.) plus Eraser Backing (2 lb est.)
Motor Analysis
MotorRef. Volt Gear
Stall Torque
Free Speed
Free Speed
Torque at Peak
Power, 10.5 V Supply
Speed at Peak Power, 10 5 V Supply
Motor Analysis
SupplierMotor
Number Motor Name DescriptionVoltage
Gear Ratio
Torque (lb-ft)
Speed (rpm)
Speed (rad/s)
V Supply (lb-ft)
10.5 V Supply (rad/s)
Fisher-Price
74550-0642
Power Wheels
Motor only 12 0.477 24000 2513 0.209 1100
CIM FR801-001 (Chiaphua, Atwood)
Keyed output shaft ccw 12 1 81 5342 559 0 789 244Atwood) shaft, ccw 12 1.81 5342 559 0.789 244
Fisher-Price
74550-0642
Power Wheels
Motor and gearbox 12 181 56.8 133 13.9 25.1 6.1
Globe 409A586 2WD/4WD transfer mtr.
Motor only 12 0.182 9390 983 0.0811 429
Taigene 16638628 Sliding (van) door
Worm Gearmotor 10.5 22.1 75 7.9 9.59 3.4
Globe 409A587 2WD/4WD transfer mtr.
Planetary Gearmotor 12 117 9.59 80 8.4 4.79 3.7
Nippon E6DF Window Lift WormNippon-Denso
E6DF-14A365-BB
Window Lift Worm Gearmotor 12.6 6.79 92 9.6 2.95 4.1
Minimum Torque Requirements:Horizontal Sliding = 1.3 lb-ftVertical Sliding = 1.875 lb-ft
Motor Analysis
MotorRef. Volt Gear
Stall Torque
Free Speed
Free Speed
Torque at Peak
Power, 10.5 V Supply
Speed at Peak Power, 10 5 V Supply
Motor Analysis
SupplierMotor
Number Motor Name DescriptionVoltage
Gear Ratio
Torque (lb-ft)
Speed (rpm)
Speed (rad/s)
V Supply (lb-ft)
10.5 V Supply (rad/s)
Fisher-Price
74550-0642
Power Wheels
Motor only 12 0.477 24000 2513 0.209 1100
CIM FR801-001 (Chiaphua, Atwood)
Keyed output shaft ccw 12 1 81 5342 559 0 789 244MINIMUM TORQUE NOT MET
MINIMUM TORQUE NOT MET
Atwood) shaft, ccw 12 1.81 5342 559 0.789 244
Fisher-Price
74550-0642
Power Wheels
Motor and gearbox 12 181 56.8 133 13.9 25.1 6.1
Globe 409A586 2WD/4WD transfer mtr.
Motor only 12 0.182 9390 983 0.0811 429MINIMUM TORQUE NOT MET
MINIMUM TORQUE NOT MET
Taigene 16638628 Sliding (van) door
Worm Gearmotor 10.5 22.1 75 7.9 9.59 3.4
Globe 409A587 2WD/4WD transfer mtr.
Planetary Gearmotor 12 117 9.59 80 8.4 4.79 3.7
Nippon E6DF Window Lift Worm
BULKY COMPARED TO GLOBE MOTOR
Nippon-Denso
E6DF-14A365-BB
Window Lift Worm Gearmotor 12.6 6.79 92 9.6 2.95 4.1
Horizontal Sliding: speed high torqueMinimum Torque Requirements:
FACTOR OF SAFETY TOO SMALL
Horizontal Sliding: speed, high torqueVertical Sliding: small, light weight
Horizontal Sliding = 1.3 lb-ftVertical Sliding = 1.875 lb-ft
Motor Analysis
SupplierMotor
Number Motor Name Description
Ref. Voltage
Gear Ratio
Stall Torque (lb-ft)
Free Speed (rpm)
Free Speed (rad/s)
Torque at Peak Power,
10.5 V Supply (lb-ft)
Speed at Peak Power, 10.5 V Supply (rad/s)
Motor Analysis
Supplier Number Motor Name Description age Ratio (lb ft) (rpm) (rad/s) Supply (lb ft) Supply (rad/s)
Fisher-Price
74550-0642 Power Wheels Motor and gearbox 12 181 56.8 133 13.9 25.1 6.1
Globe 409A587 2WD/4WD transfer mtr.
Planetary Gearmotor 12 117 9.59 80 8.4 4.79 3.7
Free Speed Calculations:Across the board
secin.7.13
rev1in.5.4
rad2rev1
secrad1.6
=⋅
⋅⋅π
πFisher‐Price:
secin.9.6
rev1in.75.3
rad2rev1
secrad7.3
=⋅
⋅⋅π
πGlobe:
Up/down board
secevdsec π
Can the cable subassembly overcome frictional forces without breaking?
P d t i lProposed materials:Bicycle brake cable (steel)Rubberized Nylon cable
Here, we will analyze the 5 mm cable with the lowest tensile strength to ensure a sufficiently high factor of safety for the stationary board. Weight considerations are largely ignored for this analysis as they not pertinent to the direction of motion.
A distributed load of 7 lbf is applied against the direction of motion of the cable due to the board friction present. Thus the motor force must overcome the friction force. Since there are boa d ct o p ese t us t e oto o ce ust o e co e t e ct o o ce S ce t e e a e2 pulleys (top and bottom) aiding the path of motion of the eraser, the stress on the cables is halved indicating that the cable tension in summation must overcome eraser assembly friction, pulley/bearing friction, and applied motor stress.
FF
With the chosen motor (maximum torque of 34 N-m = 25.077 ft-lb.) at a distance of 2 ft, the lb 7
022
0
=>
>−+∴>∑fm
fmm
x
FF
FFFF
cable has a F of S of at least 20 which is ample to ensure that the cable, even with the smallest tensile strength, will not stretch or deform and will definitely not snap. This means that cost can largely dictate the cable material that is chosen.
Automatic Whiteboard WiperAutomatic Whiteboard Wiper
• Next TimeNext Time– Part Drawings
• Prepare a complete set of part drawings• Prepare a complete set of part drawings– Must contain enough information so the part can be fabricated
• Drawings are for the actual design, not for the prototype
