analysis of a frontal impact of a formula sae vehicle

8/11/2019 Analysis of a Frontal Impact of a Formula SAE Vehicle

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Analysis of a FrontalImpact of a Formula

SAE VehicleDavid RisingJason KaneNick Vernon

Joseph AdkinsDr. Craig Hoff

Dr. Janet Brelin-Fornari

Kettering University


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Overview

Introduction

Formula SAE Impact Attenuator Rules Methodology

Evaluation Criteria HIC, Neck Loads and Moments, Nij, Femur Loads

Testing Procedures Baseline Testing, Pulse Shape Comparison, Critical Speed Test

Results Comparison of evaluation criteria

Kinematic Analysis using high speed video Conclusions


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Introduction - Formula SAE

Worldwide collegiate

competition

Students conceive,design, and fabricate

small formula style cars Driver risks have never

been tested in a crash

environment


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Introduction - Formula SAE ImpactAttenuator Rules

3.3.6.4 Impact Attenuator Data Requirement

The team must submit calculations and/or test data toshow that their Impact Attenuator, when mounted on the

front of the vehicle with a total mass of 300 kgs (661 lbs)and run into a solid, non-yielding impact barrier with a

velocity of impact of 7.0 m/s (23 ft/s), would give andaverage deceleration of the vehicle not to exceed 20 g.

Does not specify deceleration time-history pulse

shape


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Introduction Methodology

Evaluate the Impact

Attenuator rule based onATD Injury Criteria Explore the Safety

Envelope by increasingimpact speeds

Evaluate Pulse Shape Kinematic Analysis Using

High Speed Video Evaluate HANS Device

Effectiveness


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Typical Test

Test Conditions

7.0 m/s

16.5 g avg 35 ms


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Evaluation Criteria - HIC

Head Injury Criteria (HIC) is used to evaluate the

severity of head trauma based on accelerations

HIC consists of two criterion, HIC36 and HIC15 HIC36 and HIC15 calculate the highest average

acceleration over a 36 ms and 15 ms periodrespectively

Values for HIC36 that exceed 1000 and values of

HIC15 that exceed 700 represent a 31% chance ofskull fracture


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Evaluation Criteria - Nij

Nij criteria is based on the resultant neck loads and

moments experienced by the ATD Nij represents the four major combinations of neck

loading in a frontal crash Nce: Compression load and Extension moment

Ncf: Compression load and Flexion moment Nte: Tension load and Extension moment Ntf: Tensions load and Flexion moment

Nij values that exceed 1.0 and individual load and

moment values that exceed their IARV represent a22% chance of AIS 3 neck injury


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Evaluation Criteria - Femur

Axial load cell in femur measurescompression and tension loads

Axial loads that exceed 10,000 N represent a

35% chance of a moderate injury to the femur


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Procedure

Baseline Test Replicate as close as possible the deceleration due to the impact attenuator:

7.0 m/s, 20 g average, 35 ms pulse Pulse Shape Comparison

Increased speed to 12.5 m/s, average of 16 g, 80 ms pulse Three pulse shapes compared: early high-g peak, constant g, and late high-

g peak

Each pulse shape compared both with and without the use of a HANSdevice

Critical Speed Test Increased impact speed until Injury Assessment Reference Values were

exceeded Test specifications: 15.6 m/s, 80 ms pulse, 20 g average deceleration

Utilized late high-g pulse shape and was tested with and without HANS


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Early High-g Pulse


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Constant-g Pulse


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Late High-g Pulse


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Results Baseline

Showed no condition where IARV were exceeded

Test one, two, and three values were negligiblewhen compared to the IARV

Many values in test four were much closer to the

IARV May be due to much higher initial velocity (11.2 m/s) and

average deceleration (27.6) than tests one, two, andthree

Femur load cell was not utilized


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Results - Baseline

-224394.869.50.66900.9620.293-101.197.47-413.4234611.227.6Baseline Test #4

-43.443.436.20.1580.0290.2960.200-32.4533.1-449.1394.56.916.6Baseline Test #3

-2839.930.60.1710.0570.2660.230-31.4135.14-475.3379.37.116.7Baseline Test #2

----0.1650.0570.2140.240-25.3534.17-413.7381.76.915.7Baseline Test #1

1000070010001111-135310-40004170IARV

AxialFemurLoad(N)

HIC15

HIC36

PeakR

esultantHeadAccel

(g's)

Ntf

Ncf

Nte

Nce

Extensio

nNeckMoment(N-m)

Flexion

NeckMoment(N-m)

CompressionNeckLoad(N)

Tens

ionNeckLoad(N)

V

(m/s)

AverageAcceleration(g's)

Test


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Results - Baseline

ATD did not

experiencemaximumacceleration

until after 35milliseconds

TestConditions: Baseline

Test #4


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Results - Pulse Shape

No condition where IARVs were exceeded

On average the constant-g measured valuesexceeded that of the early-g and late-g pulses

The average initial velocity of the constant-g pulse

was also 1 m/s higher that the early-g pulse and2.5 m/s higher that the late-g pulse

The addition of the HANS device reduced the

tension neck load in every test


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Results Pulse Shape

4394373452670.3310.0940.40.387-52.7842.29-509.5159012.514.5Late High-g HANS #2

1485354437660.2820.0930.4090.433-54.9647.49-516.8137012.517.7Late High-g HANS #1

353149240540.42500.1730.195-22.8122.86-461.3264111.212.9Late High-g #2

484273449550.53400.3240.245-31.7415.58-505.2329712.116.6Late High-g #1

3581321423620.250.1520.3150.695-65.2648.18-870.6137012.517.5Constant-g HANS#2

4614364587630.39800.3280.608-57.5238.29-1184206612.518.2Constant-g HANS#1

4877306557550.61400.5040.691-73.3825.16-1011363112.516.8Constant-g #2

3866281450520.53500.4260.651-71.1219.88-950.3324012.517.7Constant-g #1

4043312507680.5050.1170.477NA-41.6771.23-270.9187612.117.6Early High-g HANS #2

2342258400750.43300.3280.469-55.6464.29-710.4186211.215.8Early High-g HANS #1

1821249420740.58200.4810.344-45.9441.42-814.6311511.615.6Early High-g #2

2256251421780.53500.4260.651-44.7729.91-927.8313111.616.9Early High-g #1

1000070010001111-135310-40004170IARV

AxialFemur

Load(N)

HIC15

HIC36

PeakResult

antHead

Acc

el(g's)

NtfNcfNteNce

Extension

Neck

Moment(N-m)

FlexionNeck

Moment

(N-m)

CompressionNeck

Lo

ad(N)

TensionNe

ckLoad

(N)

V(m

/s)

AverageAcc

eleration

(g's)

Test


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Results Pulse Shape

V(

m/s)

Average

Acceleration(g's)

AxialFem

urLoad

(N

)

HIC

15

HIC

36

PeakRe

sultant

HeadAc

cel(g's)

NtfNcfNteNce

ExtensionNeck

Momen

t(N-m)

FlexionNeck

Momen

t(N-m)

Compr

ession

NeckLoad(N)

TensionNeck

Load

(N)

Test

602%72%29%22%-36%-63%86%98%134%6%-50%8%9.2%Late High-g

-6%17%0%17%-44%--31%-3%-15%92%5%-50%0%3.5%Constant-g

57%14%8%-6%-16%--11%-6%7%90%-44%-40%0%2.8%Early High-g

Comparison with and w/o HANS

2940363444670.3070.0940.4050.41-53.944.9-513148012.516.1Late High-g Hans Avg

4098342505630.3240.0760.3220.652-61.443.2-1027171812.517.9Constant-g Hans Avg

3193285453710.4690.0590.4030.469-48.767.8-491186911.616.7Early High-g Hans Avg

Average Values w/ HANS

419211344540.4800.2490.22-27.319.2-483296911.614.8Late High-g Avg

4372294504540.57500.4650.671-72.322.5-981343612.517.3Constant-g Avg

2039250420760.55900.4540.498-45.435.7-871312311.616.3Early High-g Avg

Average Values w/o HANS


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Results Critical Speed

During the critical late high-g test the tension neck load,

HIC15, HIC36, and femur load IARV were exceeded The use of the HANS device reduced the tension neck load

below the IARV

The use of the HANS did not affect the HIC15, HIC36, and

femur load values AxialFemurLoad(N)

HIC15

HIC36

PeakResultantHead

Accel(g's)

NtfNcfNteNce

ExtensionNeck

Moment(N-m)

FlexionNeckMoment

(N-m)

CompressionNeck

Load(N)

TensionNeckLoad

(N)

V(m/s)

AverageAcceleration

(g's)

Test

1349010421412960.4180.1030.3510.491-45.4240.4-1421230515.620.0Critical Late High-g HANS

13550114315491010.8130.0750.7020.589-58.6957.92-1150481715.620.0Critical Late High-g


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Results Critical Speed Kite

Graph (no HANS)

Test Conditions

15.6 m/s

20 g avg 80 ms


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Results Critical Speed Kite

Graph (w/ HANS)

Test Conditions

15.6 m/s

20 g avg 80 ms


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Conclusions

The baseline tests that approximated the Formula

SAE rules (7.0 m/s, 20-g average deceleration)resulted in measured injury values that were negligiblecompared to the IARV

The tests comparing pulse shape all resulted in values

which were less than the IARV The statistically highest values comparing pulse shape

were seen during the constant-g test however, theaverage acceleration was slightly higher for thesetests


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Conclusions Cont.

The addition of a HANS device reduced thetension neck load in every test and brought thetest value below the IARV for the critical speed

test

An impact from 15.6 m/s with a 20-g averagedeceleration rate was found to pose a seriousrisk of injury to the driver, with and without theHANS device.

To reduce the risk of injury to the driver,horizontall mounted tubes should be laced a


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Acknowledgements

Janet Brelin-Fornari, John Young and the Kettering

University Crash Safety Center for the use of theirfacility.

Denton Safety Systems for the use of their

equipment Jamie Jones and Red Horse Racing for the donation

of a HANS device for testing.

Lynn St. James and HANS for the donation of twonew HANS devices.


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References Gideon, T., Melvin, J., Streetz, L., and Willhite, S. ATD Neck Tension

Comparisons for Various Sled Pulses, Society of Automotive

Engineers, 2002, SAE 2002-01-3324. Society of Automotive Engineers. 2006 Formula SAE Rules.

http://students.sae.org/competitions/formulaseries/

Eppinger R., Sun E., Bandak F., Haffner M., Khaewpong N., MalteseM., Kuppa S., Nguyen T., Takhounts E., Tannous R., Zhang A., Saul

R. Development of Improved Injury Criteria for the Assessment ofAdvanced Automotive Restraint Systems II. November, 1999, TheNational Highway Traffic Safety Administration.

FMVSS 208. May 27, 1998 The National Highway Traffic SafetyAdministration, DOT.

Trauma.org. Abbreviated Injury Scale. Accessed on August 22, 2006.

http://www.trauma.org/scores/ais.html.


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Thank You For Your Time

Any Questions?

analysis of a frontal impact of a formula sae vehicle

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