sae mini baja
TRANSCRIPT
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SAE Mini BajaEngineering Analysis
Chris Bennett, Eric Lockwood, Anthony McClinton,
Robin McRee, Colin Pemberton
November 18, 2013
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Overview
ā¢ Design Problem
ā¢ SolidWorks Simulation
ā¢ Refined Frame Designs
ā¢ Analysis Assumptions
ā¢ Strength Tests
ā¢ Simulation Results
ā¢ Project Plan
ā¢ Conclusion
Anthony McClinton 2
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Problem Statement
ā¢ NAU has not won an SAE Baja event.
ā¢ Goal is to design the lightest possible frame within the SAE rules.
Anthony McClinton 3
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SolidWorks Simulation
ā¢ Beam elements for frame analysis
ā¢ Tetrahedral elements for solid components
Colin Pemberton 4
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Refined Frame Designs
Colin Pemberton
Design 5 Design 6
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Refined Frame Designs
Colin Pemberton
Design 8Design 7
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Simple Loading Case
ā¢ 6000 lb distributed load on the roof
ā¢ Design with highest FOS
ā¢ Design with most even stress distribution
ā¢ Advanced tests performed on the best design
Colin Pemberton 7
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Simple Loading Results
Colin Pemberton
Design Max Stress [ksi] Max Deflection [in] Yield Safety Factor
5 61.61 0.256 1.08
6 61.20 0.210 1.09
7 60.16 0.202 1.11
8 56.89 0.206 1.17
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Frame Impact Tests
ā¢ Drop Test
ā¢ Front Collision Test
ā¢ Rear Collision Test
ā¢ Side Impact Test
ā¢ Static simulations at maximum impact acceleration
ā¢ All are worst-case scenario
Eric Lockwood 9
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Drop Test
Eric Lockwood 10
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Eric Lockwood
Drop Test
š¹ = š āšā
š”
ā¢ F = force
ā¢ m = mass
ā¢ g = acceleration of gravity
ā¢ h = drop height
ā¢ t = impulse time
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Front Collision Test
Eric Lockwood 12
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Rear Collision Test
Eric Lockwood 13
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Side Impact Test
Eric Lockwood 14
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Impact Tests
Eric Lockwood
š¹ = š āš0š”
ā¢ F = force
ā¢ m = mass
ā¢ V0 = initial velocity
ā¢ t = impulse time
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Analysis Assumptions
ā¢ Frame Weight of 100.29 lb
ā¢ Drivetrain Weight of 120 lb
ā¢ Suspension Weight 50 lb per corner
ā¢ Driver Weight of 250 lb
ā¢ AISI 4130 Tubing, 1.25 in Diameter, 0.065 Thickness
Eric Lockwood 16
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Loading Example
Eric Lockwood 17
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Drop Test Deflection
Robin McRee 18
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Drop Test Safety Factor
Robin McRee 19
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Front Collision Deflection
Robin McRee 20
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Front Collision Safety Factor
Robin McRee 21
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Rear Collision Deflection
Robin McRee 22
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Rear Collision Safety Factor
Robin McRee 23
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Side Impact Deflection
Robin McRee 24
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Side Impact Safety Factor
Robin McRee 25
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Impact Results Summary
Robin McRee
Test Max Deflection [in] Yield Safety Factor
Drop 0.089 5.32
Front Collision 0.135 2.90
Rear Collision 0.263 1.45
Side Impact 0.363 1.01
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Tab Shear Test
ā¢ Driver harness mounts
ā¢ Suspension mounts
ā¢ Drivetrain mounts
ā¢ Extreme loading cases
ā¢ Intentionally overdesigned
ā¢ Adds little additional weight
Chris Bennett 27
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Driver Harness Mount Deflection
Chris Bennett 28
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Driver Harness Mount Safety Factor
Chris Bennett 29
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Frame Tab Deflection
Chris Bennett 30
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Frame Tab Safety Factor
Chris Bennett 31
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Tab Shear Results
Chris Bennett
Test Max Deflection [in] Yield Safety Factor
Driver Harness 0.001 4.70
Frame Tab 0.024 1.50
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Engineering Design Targets
Anthony McClinton
Requirement Target Actual
Length [in] 108 88.175
Width [in] 40 32
Height [in] 41 44.679
Bending Strength [N-m] 395 485.95
Bending Stiffness [N-m2] 2789 3631.14
Wall Thickness [in] 0.062 0.065
Pass Safety Rules TRUE TRUE
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Project Plan
Anthony McClinton 34
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Conclusion
ā¢ Problem Overview - NAU has not won an SAE Mini Baja competition. The Team will build the lightest possible frame.
ā¢ SolidWorks Simulation - Beam analysis used for frame. Tetrahedral analysis used for tabs.
ā¢ Refined frame designs ā Designs 5 through 8 were analyzed. Design 8 had the highest safety factor.
Anthony McClinton 35
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Conclusion
ā¢ Drop, front impact, rear impact, and side impact tests were performed. Design 8 passed all tests.
ā¢ Seat belt harness mount and frame tabs were analyzed. Both are well within safety limits.
ā¢ Team is on schedule. More time was allocated for frame analysis.
Anthony McClinton 36
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References
ā¢ Owens, T., Anthony, Jarmulowicz, D., Marc, Jones, Peter āStructural Considerations of a Baja SAE Frame,ā SAE Technical Paper 2006-01-3626, 2006.
ā¢ Silva, Martins, Maira, Oliveira, R. P. Leopoldo, Neto, C. Alvaro, Varoto, S. Paulo, āAn Experimental Investigation on the Modal Characteristics of an Off-Road Competition,ā SAE Technical Paper 2003-01-3689, 2003.
ā¢ Tester, John, Northern Arizona University, personal communication, Nov. 2013.
Anthony McClinton 37