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SPRING PROGRESS REPORTSIDE UNDER RIDE GUARD ANDAERODYNAMIC FAIRING
Kenji PetrucciCody JonesSam Murphy
Introduction
Passenger cabin intrusion, PCI
Severe Injury/fatalities
No requirement to prevent side under ride
Background
Rear guard initially required in 1953 but were highly
ineffective; safer guards required in 1998 by NHTSA
Background
Over 4 million trailers travel on US roads, none with side under ride guards
Approx 226 people die annually due to side under ride
98% of collisions with a trailer result in at least 1 fatality
*all pictures from http://www.crashforensics.com/truckunderride.cfm
Customer needs
Absorb force of a light duty vehicle (6000lbs) traveling at 35mph and prevent under ride
Cost efficient and easily installed by end user; bolt-on “kit” configuration
Provide aerodynamic qualities Offset cost of purchase/installation Increase fuel efficiency Reduction in total hauling capacity
Product Specifications
Impulse time of 200ms Impulse force vs. static force
Safety factor N = 2tvmJ avgF Impulse
English SI
Mass 6000lb 2722kg
Velocity 35mph 15.65m/s
Δt 0.2s 0.2s
Δv 35mph 15.65m/s
Table 1
Product Specifications
vmtFJImpulse avg
kNs
smkg
t
vmFavg 213
/
2.0
65.152722
Units of N*s
Factor of safety = 2 means double the impulse force
Nearly 500,000N of force for static load
Product Specifications
Modular vs. single unit
Impact always on at least 2 sections
Force per bar approximately 213,000N
47,884lbs
Final Design
Aluminum 1.5in (0.25in wall thickness) square tubing 0.25in thick brackets for welding
Steel 2in (0.25in wall thickness) square tubing Weld directly to trailer I-beam
6in x 24in x 0.5in aluminum impact bar
Final Design Aluminum w/brackets
Final Design Steel
Stress/Deflection Analysis 6061-Al Max stress
100ksi for steel 85ksi for aluminum
Max stress at joint corners Impact bar failure acceptable
Summary
Aluminum questionable (6061-T6) UTS = 45ksi Tensile yield strength = 40ksi UBS = 88ksi Bearing yield strength = 56ksi
Max deflection at ends acceptable, even if failure occurs
Safety factor of 2 realistic and achievable
Fabrication/Assembly/TestingID Task Name Duration Start Finish Predecessors
1 Design Finalization 4 days? Thu 1/13/11 Tue 1/18/11
2 CAD Modeling 2 days? Thu 1/13/11 Fri 1/14/11
3 Stress Analysis 1 day? Mon 1/17/11 Mon 1/17/11 2
4 Bill of Materials 1 day? Tue 1/18/11 Tue 1/18/11 3
5 Progress Report Presentation 2 days? Wed 1/19/11 Thu 1/20/11 1
6 Team Evals 3 1 day? Fri 1/21/11 Fri 1/21/11 5
7 Staff Meeting 3 days? Tue 2/1/11 Thu 2/3/11 5
8 Meet with Sponsors 1 day? Fri 2/4/11 Fri 2/4/11 5,7
9 Mid Point Review Presentation 1 day? Tue 2/22/11 Tue 2/22/11 8
10 Staff Meetings 5 days Mon 2/28/11 Fri 3/4/11 9
11 Order Parts/Materials 7 days? Mon 2/28/11 Tue 3/8/11 9
12 Fabrication 12 days Wed 3/9/11 Thu 3/24/11 11
13 Machining 4 days Wed 3/9/11 Mon 3/14/11 11
14 Welding 4 days Tue 3/15/11 Fri 3/18/11 13
15 Mounting 4 days Mon 3/21/11 Thu 3/24/11 14
16 Crash Test / FMVSS Test 5 days? Fri 3/25/11 Thu 3/31/11 15
17 Staff Meetings 1 day? Thu 3/17/11 Thu 3/17/11 10
18 Staff Meetings 1 day? Tue 3/29/11 Tue 3/29/11
19 Final Project Presentation 13 days? Tue 3/22/11 Thu 4/7/11
Risks
Time constraints Parts/Shipping
Fabrication Welding, machining
Testing Correct material choice
Acknowledgements
Dr. Hollis Faculty advisor
Perry Ponder Sponsor
Andrew Magaletti
References
Cengel, Yunus A., Robert H. Turner, and John M. Cimbala. Fundamentals of Thermal-fluid Sciences. 3rd ed. Boston: McGraw-Hill, 2008. Print.
Wolfson, Richard. Essential University Physics. 1. San Francisco: Pearson Addison Wesley, 2007. Print
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