Drive Shaft
Problem Statement
Design a drive shaft for a 2-wheel-drive battery electric vehicle
Must be securely connected to the power transmission using
threaded fasteners
Must be able to withstand a maximum torque of 500 Nm
Ensure the drive shaft is safe, reliable and efficient
Manufacture 200,000 drive shafts
Initial Design

Slip joint for allowed movement during
changes in suspension

Basic flange and thread design to attach to
differential and motor

Application
 Weather Conditions
➢ Corrosion resistance
➢ Impact resistance
➢ temperature fluctuations
➢ Movements and usability
➢ U-Joints for efficiency
➢ Slip joints for shifts in suspension

•
•
High Torque and high rpm environment
Ideally want metals and composites
With high yield and tensile strength
Optimal Design

One flange on each side to connect
to the differential and the motor of
the vehicle.

One guided hallowed out slip joints
for better stability and handing

Cylindrical cross section instead of
hexagonal, optimized for low weight,
faster manufacturing and overall
strength

Improved universal joints
Shaft Geometry
• Shaft Diameter: 5.5 in
• Total Length: 86.63 in ± 3 in
• Slip joint: 6 in in total
Spins via two universal joints mounted using flanges on each side. The smaller flange is the
motor side while the large flange is on the differential side.
Shaft Geometry Cont.
Shaft Break down
Assembly and application
Application
• High Torque and high rpm environment
• Ideally want metals and composites
• With high yield and tensile strength
• Weather Conditions
• Corrosion resistance
• Impact resistance
• temperature fluctuations
Movements and usability
• U-Joints for efficiency
• Slip joints for shifts in suspension
Calculations
Rads/s * 60s/min * ½π = Rpm
L: Lenth of the shaft
D: diameter of the shaft
G: gravity
E:Young's modulus
Y: Specific weight
Materials
Specific Weight
(g/cc)
Youngs
Modulus (Gpa)
6061-T6 AL
2.7
68
1045 Cold Rolled
Steel
7.858
200
1023 Steel
7.858
69
6061-T6 Al = 8696 RPM
1045 Cold rolled steel = 8742 RPM
1023 Steel = 5135 RPM
Threaded Fastners

Zinc Hex Head Screw-Aluminum
Coated, Grade 8 Steel, 5/16"-18
Thread Size, 2" Long, Fully Threaded"

Use a high-strength Aluminum screw
with a 5/16-inch diameter, 18 threads
per inch, a length of 2 inches. It has a
hexagonal head and is fully
threaded, making it suitable for
various applications where strength
and corrosion resistance are
important.
Fastners Load calculations

T=K*F*d

F=preload(ft/lbs)

N= number of bolts T=Torque K=friction=0.2 d=bolt diameter

T= 0.2*1,476ft/lbs*(5/16in)

T=0.09225 kip= 410 newtons

Need two bolts to meet the 500 newtons of torque

Total bolts is 4 because we doubled the number of bolts to ensure a
factor of safety of two
Material Selection
 Steel
 High strength
 Durable
 Susceptible to
corrosion
 Cheapest
material
 Critical speed
•Aluminum alloy
•Lightweight
•High strength
•Corrosionresistant
•More expensive
than steel
•Critical speed
• Carbon Fiber
•Very strong
•Very lightweight
• Limited
availability
• Most expensive
option
• Critical speed
Aluminum Alloy
ALUMINUM PROVIDED A VERY
HIGH STRENGTH TO COST
RATIO
CORROSION RESISTANT
THE LIGHTWEIGHT WILL HELP
WITH VEHICLE PERFORMANCE
AND FUEL EFFICIENCY
A HIGH CRITICAL SPEED
Manufacturing
Process

The slip joint for the drive shaft will be
created using CNC turning and facing
to start

After this milling and drilling will allow
the part to be hollowed

Finally cutting and slotting is done to
allow the joints to move

U-joints are created using turning
followed by center drilling

Followed by using milling and drilling

Flanges are made using turning and
facing

Followed by milling and drilling
Safety

Goal safety is 1.5-2.25

Our yield strength was 2.750x10^8

Our maximum stress was 2.558x10^6

When compared the yield strength is over the 2.25 goal factor of
safety
FEA

1045 Steel Cold rolled

Yield Strength:
530mpa
FEA 6061-T6 Aluminum
Yield Strength on both scenarios is 275 mpa. Maximum stress is still
under the yield Strength
Cost Analysis
Aluminum cost $355.89 per shaft
 CNC cost


3 Axis ($20-$30)- 4hrs*$ 25per hr= $100


CNC Turning ($20)- 1.5hr*$20per hr=$30


slip joint, shaft portion, flange and spider
Threaded fastener cost $7.69 per flange


Yoke sections, flange and spider
Mcmastercar
Total

Raw cost $355.89

CNC cost-$130

Fasteners –$7.69*2= $15.38

Total- $501.27*200,000= 100.25 million dollars
Citation

https://www.azom.com/article.aspx?ArticleID=6524

https://www.portlandbolt.com/technical/bolt-torque-chart/#bolttorque-a354bd