SAE Mini Baja Concept Generation and Selection Chris Bennett, Eric - - PowerPoint PPT Presentation

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SAE Mini Baja Concept Generation and Selection Chris Bennett, Eric Lockwood, Anthony McClinton, Robin McRee, Colin Pemberton October 28, 2013 Overview Design Problem Tubing Size and Material Frame Geometry Welding Method

SLIDE 1

SAE Mini Baja

Concept Generation and Selection

Chris Bennett, Eric Lockwood, Anthony McClinton, Robin McRee, Colin Pemberton October 28, 2013

SLIDE 2

Overview

Design Problem
Tubing Size and Material
Frame Geometry
Welding Method
Project Plan
Conclusion

Anthony McClinton 2

SLIDE 3

Problem Statement

NAU has not won an SAE Baja event.
Goal is to design the lightest possible frame within the

SAE rules.

Anthony McClinton 3

SLIDE 4

Tubing Selection

SAE specifies AISI 1018 Steel
1” Outside Diameter
0.120” Wall Thickness
Other Sizes Allowed
Equivalent Bending Strength
Equivalent Bending Stiffness
0.062” Minimum Wall Thickness

Robin McRee 4

SLIDE 5

Bending Strength and Stiffness

𝑇𝑢𝑗𝑔𝑔𝑜𝑓𝑡𝑡 = 𝐹 ∙ 𝐽 𝑇𝑢𝑠𝑓𝑜𝑕𝑢ℎ = 𝑇𝑧 ∙ 𝐽 𝑑 E = 29,700 ksi for all steel I = second moment of area Sy = yield strength c = distance from neutral axis to extreme fiber

Robin McRee 5

SLIDE 6

AISI 1018 AISI 4130

Diameter [in] Wall Thickness [in] Stiffness [in-lb] Strength [in2-lb] 1.000 0.120 971.5 3.513

Diameter [in] Wall Thickness [in] Stiffness [%] Strength [%] Weight [%] 1.000 0.120 100 118 100 1.125 0.083 113 119 81.9 1.125 0.095 126 131 92.7 1.250 0.065 130 122 72.9 1.375 0.065 176 150 80.6 1.500 0.065 231 181 88.3

Robin McRee 6

SLIDE 7

Final Selection

Robin McRee 7

SLIDE 8

Frame Geometry

Lightweight
Stability
Rigidity
Simplicity
Driver Safety

Colin Pemberton 8

SLIDE 9

Design 1

Advantages:

Rigidity
Driver safety
Maneuverability

Disadvantages:

Heavy
Unstable
Manufacturability

Colin Pemberton 9

SLIDE 10

Design 2

Advantages:

Lightweight
Maneuverability
Manufacturability

Disadvantages:

Less Rigid
Unstable

Colin Pemberton 10

SLIDE 11

Design 3

Advantages:

Stability
Interior space
Rigidity

Disadvantages:

Maneuverability
Heavy
Manufacturability

Colin Pemberton 11

SLIDE 12

Design 4

Advantages:

Stability
Interior space
Rigidity

Disadvantages:

Less Maneuverable
Unstable
Manufacturability

Colin Pemberton 12

SLIDE 13

Frame Design Criteria

Amount of material [feet]
Length [inches]
Width [inches]
Height [inches]
Number of Bends
Number of individual tubes

Eric Lockwood 13

SLIDE 14

Decision Matrix

Eric Lockwood 14

Weight Design 1 Design 2 Design 3 Design 4 Amount of Material [ft] 9 109 94 105 107 Length [in] 5 83 78 100 100 Width [in] 1 32 33 30 31 Height [in] 5 45 44 39 44 Number of Bends 1 10 10 4 4 Number of individual tubes 1 65 43 50 55

Total 1728 1542 1724 1773

SLIDE 15

Final Design

Eric Lockwood 15

SLIDE 16

Concept Selection - Welding

3 types of welding processes
Shielded Metal Arc Welding (SMAW)
Gas Metal Arc Welding (GMAW)
Gas Tungsten Arc Welding (GTAW)

Chris Bennett 16

SLIDE 17

Design Criteria for Welding Selection

Ease of process
Prep work required for welding
Clean up required after welding

Chris Bennett 17

SLIDE 18

SMAW

Requires no prep work
Requires a lot of cleaning
nce done
Need special welding rod
Can be difficult to weld in

awkward positions

Chris Bennett 18 Wikimedia

SLIDE 19

GTAW

A lot of prep work

required

No clean up after welding
Very difficult to weld in

tight spots

Chris Bennett 19 Advantage Fabricated Metals

SLIDE 20

GMAW

Require no prep work
Very little cleaning after

welding

No special welding wire

needed

Easy to weld all positions

Chris Bennett 20 Ever Last Generators

SLIDE 21

Project Plan

Anthony McClinton 21

SLIDE 22

Conclusion

Design Problem – NAU has not won a Mini Baja

competition in recent years. Team will design a light frame to maximize performance.

Tubing Size and Material – AISI 4130 1.25” x 0.065

was chosen as the tube diameter and thickness. It is stronger and 27% lighter than the stock tubing.

Frame Geometry – Design 2 was chosen because it is

the lightest and easiest to construct.

Anthony McClinton 22

SLIDE 23

Conclusion Continued

Welding Method – GMAW was chosen due to its

simple set up, operation, and cleanup.

Project Plan – Preliminary frame design and ordering

materials deadlines had to be pushed back. Team is on schedule to complete the frame by the end

f the semester.

Anthony McClinton 23

SLIDE 24

References

http://upload.wikimedia.org/wikipedia/commons/f/fc/SM

AW_setup.PNG

http://www.everlastgenerators.com/arc-welding-

process.php

http://www.advantagefabricatedmetals.com/tig-

welding.html

Anthony McClinton 24