The Effect of The Effect of Different “Highway Different “Highway

Barrier” Materials on Barrier” Materials on Force and Time of Force and Time of

Impact in a Impact in a Simulated Car CrashSimulated Car Crash

Danilo, Louis, and BreeDanilo, Louis, and BreePHYS 399PHYS 399Group 2Group 2

BackgroundBackground• Demonstrates the first law of momentum• In a collision, an object experiences a

force for a specific amount of time which results in a change in momentum

• Tested different materials to simulate which one will be effective to save lives during collision– soft sponge, foam, paper and plastic bubbles

• By increasing the time of impact, we reduce the immediate force of the impact for the occupants of the car while maintaining a consistent momentum

• Therefore we want to find the most effective material to meet this need

PurposePurpose

HypothesisHypothesis• Research Question: Which “highway

barrier” material will best increase the time of impact in a simulated car crash?

• If various “highway barrier” materials are tested in a simulated car crash, then a hollow inelastic material will increase the time of impact the most because it is collapsible unlike solid materials and is inelastic unlike plastic/rubber materials.

Lab Set-Up

•The ramp should be set at some constant angle (we used about 5°) and a constant start distance of 50 cm

•This will provide a constant velocity

The Go! Motion is set-up at the top of The Go! Motion is set-up at the top of the ramp w/the Force Sensor mounted the ramp w/the Force Sensor mounted

at the base.at the base.

•Be sure to use the standard channel ports for the LabQuest Interface

•We used a single device taking 100 samples/s to do both readings to ensure that both sensors would be time synced

•The Vernier cart was mounted with an accelerometer to increase the height and weight (7N) of the car

Experimental Method:

•Mount test materials to the force sensor and re-calculate the 50 cm distance to ensure constant velocity before impact

Test materials used

Example Data Example Data Impulse=change in momentumImpulse=change in momentum

Final values

Time(s) Force(N) Velocity(m/s) F(∆t)=m(∆v)

delta(∆)=final-initial value

We must average the Force over the duration of impact.

Using above formula we see that

6.06N(0.11s)=0.714kg(0.95m/s)

0.6667 N*s=0.6783 kg*m/s

0.67 N*s=0.68 kg*m/s

Seems to indicate consistent data across two sensors

Initial values

Graph of Force and Time Graph of Force and Time relationrelation

Force during impact and Time of impact vs material

0.00

5.0010.00

15.0020.00

25.00

Control Styrofoam BubbleWrap

Foam Paperball

Fo

rce

(N)

0.00

0.05

0.10

0.15

0.20

Tim

e (s

)

Force Time

Data AnalysisData Analysis• The data we collected shows that the

Origami Ball was most effective in increasing the time of impact, thereby reducing the force of impact.

• The control and Styrofoam material was least effective in increasing the time of impact.

ConclusionConclusionImpact Duration vs Impact Force

ControlStyrofoam

Bubblewrap

Foam

Paperball

0.00

5.00

10.00

15.00

20.00

25.00

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16

Duration of impact (s)

Fo

rce o

f im

pact

(N)

Hypothesis supported?Hypothesis supported?• Yes, our hypothesis was supported

by the data that the hollow, collapsible, inelastic material was most effective in increasing the time of impact and reducing the immediate force of impact.

LimitationsLimitations• Due to digital sensitivity of the

sensors, events may occur between readings

• Sensitivity of sensors to sound, may cause discrepancy of data

• Human error for distance and start time

• Price of materials and the equipments

ImprovementsImprovements• Trigger device to prompt readings

from sensors• Consistency in size of test materials• Limitation on mass of test material• Use of the accelerometer instead of

Go! Motion sensor

ApplicationsApplications• Crumple zones extend the collision,

reducing force on passengers

Air bags inflate on contact absorbing impact Air bags inflate on contact absorbing impact Holes let air escape so collision takes even longer Holes let air escape so collision takes even longer

• Highway barriers that bend in sections to extend collisions

ExtensionExtension• Testing the ideal thickness of one

test material to increase the time of impact

• Testing airbag material rather than highway barrier

• Testing crumple zone of the car (having the material attached in front of the car)

Image CreditsImage Credits

• Slide 16 - http://image.motortrend.com/f/auto-news/volvo-wants-to-make-its-cars-injury-proof-by-2020/9805935+w562+cr1+re0+ar1/volvo-crash-test.jpg

• Slide 17 - http://media.canada.com/b17a5268-e809-4db2-a84b-06fc4c00d03e/m1x00181_crashtestdummy.jpg

• Slide 18 - http://www.eplcompositesolutions.co.uk/composite/crashBarriers.asp