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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