Car crash testing

CLASS SEMINAR ON CAR CRASH TESTING

DEPT OF MECHANICAL ENGINEERING, PES UNIVERSITY, BANGALOR 560085

CLASS SEMINAR REPORT

ON

“CAR CRASH TESTING”

BY

KUMAR MANIKANTAN T

01FM14EAT011

M TECH

1ST SEMESTER

AUTOMOTIVE TECHNOLOGY



Contents:

Abstract.

How car crash test works.

Role of dummies and its instrumentations.

Different Aspects of crash testing.

Types of crash testing

Safety systems.

Absorption mechanism of crash energy.

Crash test ratings.

Indian scenario.

Crash testing centres.

Conclusion.

Bibliography.



ABSTRACT:

Driving a car is a high in itself, but safety is important too.

Choosing a safer car is very important to help prevent

crashes and accidents.

Thus, a thorough crash-testing program is critical for the

car makers and has contributed significantly to the

improving safety of cars.

According to the New Car Assessment Program (NCAP) of

National Highway Traffic Safety Administration (NHTSA)

cars made for model year 1997 and after must pass both the

tests frontal crash testing and side impact crash testing.



HOW CRASH CAR TESTING WORKS:

Car to barrier impact

It is made to pull the vehicle with the wire and to run, and it

is made to collide with the barrier or the vehicle.

As the car crash test system, the one of a general method.

Car to car impact



Today, cars are much safer than they were some years back as

now there is a well-established testing program. Also the federal

law requires all cars to pass a 30-mile-per-hour frontal crash

test.

Crash test dummies are the key as they are used as replica for

man in a crash test. Dummies are made of materials that imitate

human physiology. Though dummies of different sizes are used,

dummy weighing 172 lbs (78 kg) and standing at 69 inches (5 ft.

9 inches or 1.75 m) tall is the most frequently used in testing.

Since 1997, GM's Hybrid III dummies became the industry

standard that complied with government regulations.

The dummy's job is to simulate a human being during a crash,

while collecting data that would not be possible to collect from a

human occupant. The dummies come in different sizes and they

are referred to by percentile and gender.



A dummy is built from materials that mimic the physiology of

the human body. For example, it has a spine made from

alternating layers of metal discs and rubber pads

With the help of a number of specially built rigs, studies are

being conducted to discover what happens when parts of the

human body collide with parts of the interior or exterior of a car.

Crash test dummies are carefully calibrated and then positioned

in vehicles to mimic the movement of humans and record crash

forces during the tests. Each complex dummy includes 25 to 40

sensors to record the forces on various parts of the body.



The dummies contain following three types of

instrumentation:

Accelerometers: - Measure the acceleration in a particular

direction. This data can be used to determine the probability of

injury. Inside the dummy's head, there is an accelerometer that

measures the acceleration in all three directions (fore-aft, up-

down, left-right). There are also accelerometers in the other

parts of the body

Load Sensors: - Inside the dummy are load sensors that

measure the amount of force on different body parts during a

crash. The maximum load in the bone can be used to determine

the probability of it breaking.

Movement Sensors: - These sensors are used in the dummy's

chest. They measure how much the chest deflects during a crash.

Before the crash-test dummies are placed in the vehicle,

researchers apply different colors of paint to the parts of the

dummies' bodies most likely to hit during a crash. The paint

marks in the car will indicate what part of the body hit what part

of the vehicle inside the cabin. This information helps

researchers develop improvements to prevent that type of injury

in future crashes



THE DIFFERENT ASPECTS OF THE CRASH

TESTING:

Infrastructure:

A crash laboratory with an advanced high-tech crash

barrier.

An outdoor test track that accommodates research for

different weather conditions

Highly advanced crash simulator

Lighting system which can provide up to 750,000 watts of

illumination without glare to film tests in slow motion. The

resulting pictures must be clear and dramatic.

Equipment for advanced component testing.

A supercomputer that crash tests non-existing cars.

A system that propels vehicles to impact, accelerating full-

size pickups up to 50 mph.



TYPES OF CRASH TESTS:

Simulating every accident type is impossible, which is why there

are number of standardized crash tests (which may resemble

most of the crashes that may take place) based on international

classifications and industry practices are used in the

development of the vehicle. This defines a repeatable way of

conducting crashes, so that improvements can be quantified and

modifications made. The three standard crash tests conducted

are:

1. Frontal Crash Test

2. Side Impact Test

3. Offset Crash Test



Frontal Crash Testing:

At 35 mph (56 kph) the car runs straight into a solid concrete

barrier. This is equivalent to a car moving at 35 mph hitting

another car of comparable weight moving at 35 mph. The

kinetic energy involved in the frontal crash test depends on the

speed and weight of the test vehicle. Full-width rigid-barrier

tests produce high occupant compartment decelerations, so

they're especially demanding of restraint systems. About 15

high-speed cameras will document the action shooting about

1,000 frames per second.



Side Impact Crash Test :

In the side test a sled (of about 1,368-kg) with a deformable

"bumper" runs into the side of the test vehicle at around 31mph.

The test simulates a car that is crossing an intersection being

sides wiped by a car running a red light. Side impacts can be of

two types: - perpendicular impact and angled impact The

protection of occupants in side impacts is more important as the

space between the car’s body and the occupant is much less than

with the front and rear.



Frontal Offset Crash Testing:

In offset tests, only one side of a vehicle's front end, not the full

width, hits the barrier so that a smaller area of the structure,

about 40% of the width of the front of the vehicle on the driver's

side must manage the crash energy. In the offset crash test the

vehicle is travels at 64kph (40mph) and collides with a crushable

aluminum barrier, which makes the forces in the test similar to

those involved in a frontal offset crash between two vehicles of

the same weight. The vehicle structure affects the outcome of an

offset frontal crash in two main ways: -absorption and

dissipation of crash energy and integrity of the passenger

compartment.



How safety system works in crash test:

Though avoiding crash is the ideal situation it is not possible

always. So the best case scenario is the smoothest crash which

results in the survival of the person in the car. Absorbing the

kinetic energy that drops from a high speed to zero after the

crash is the key in this case. Safety systems must absorb this

kinetic energy as slowly and as evenly as possible to prevent

injuries. Seatbelt forms the first line of defense and removes

some of the impact. Then milliseconds later, to stop the force of

the seatbelt from becoming too high and thus hurtful, force

limiters in the seatbelt kick in. Then the airbag releases, and it

absorbs some more of the forward motion and prevents

occupants from slamming into a hard part of car. In this way all

the systems act together to minimize the kinetic energy.

The growth of technology and continuous researches on crash

testing are helping to make the accidents less fatal and save

thousands of lives



ABSORPTION MECHANISM OF CRASH

ENERGY:

Obviously the ideal crash would be no crash at all. But, let's

assume you are going to crash, and that you want the best

possible chances of survival.

Surviving a crash is all about kinetic energy. When the

body of occupant is moving (say at 35 mph), it has a certain

amount of kinetic energy. After the crash, when it comes to

a complete stop, it will have zero kinetic energy. To

minimize risk of injury, removing the kinetic energy as

slowly and evenly as possible is done by some of the

following safety systems in the car

As soon as car hits the barrier the seatbelt can then absorb

some of your energy before the airbag deploys.

Milliseconds later as the driver moves forward towards the

airbag, the force in the seatbelt holding him back would

start to hurt him, so the force limiters make sure that the

force in the seatbelts doesn't get too high.

Next, the airbag deploys and absorbs some more of your

forward motion while protecting you from hitting anything

hard.



In a crash it is desirable that most of the crash energy is

absorbed and dissipated in the deformation of components

of each vehicle

Crumple zones are vacant spaces in the front portion of the

car that act as cushions, where metal parts are supposed to

deform and absorb all the kinetic energy of the vehicle

The engine on most cars is mounted so that in a crash, it is

forced backwards and downward so that it won't come into

the cabin and injure the occupant.

Increasing the use of engine/suspension cradles allows

designers to better control this deformation and to by-pass

very rigid components such as engine blocks, which are not

effective energy absorbers.

To avoid load concentrations it is important that the crash

forces are spread across the face of the deformable barrier.

In a collision between two vehicles the occupants of the

heavier vehicle would generally be better off, due to the

physics of the collision. In the case of four-wheel-drive

vehicles colliding with passenger cars, however, this

advantage can be diminished by a stiff front structure.



Integrity of the passenger compartment should be

maintained in the crash test. The steering column, dash,

roof, roof pillars, pedals and floor panels should not be

pushed excessively inwards, where they are more likely to

injure the occupants.



CRASH TEST RATINGS OF THE CARS:

RATING FOR FRONTAL IMPACT TESTS:

# Of stars Result

5 10% or lower chance of serious

injury

4 11% to 20% chance of serious

injury


injury


injury

1 46% or greater chance of serious

injury

RATING FOR SIDE IMPACT TESTS:

# Of

stars

Result

5 5% or lower chance of serious injury

4 6% to 10% chance of serious injury



1 26% or greater chance of serious

injury



Indian scenario:

India one of the biggest car market has the worst road safety

records in the world 1, 40,000 people die on roads every year

and close to 5 lakhs accidents.

According to recent test conducted on 5 of India’s most popular

cars from different manufacturer by Global NCAP and Institute

of road traffic education (IRT).

All the cars were tested on entry level variables only but there

was only a disturbing result.

Some cars even showed structural rigidity but anyhow failed the

test due to lack of Air bag as standard of safety.



CRASH TESTING CENTERS:

Throughout the world there are many institutes who crash

test vehicles, each organization’s test results are generally

for vehicles sold in its respective country or region.

Insurance Institute for Highway Safety (IIHS- U.S)

http://www.hwysafety.org/vehicle_ratings/ratings.htm

Euro NCAP: Established in 1997 and now backed by five

European Governments. www.euroncap.com

New Car Assessment Japan: evaluates the safety of

automobiles currently on the Japanese market.

http://www.nasva.go.jp/english

Australian NCAP (ANCAP): Australian New Car

Assessment Program (ANCAP) is supported by Australian

and New Zealan automobile clubs.

http://www.aaa.asn.au/ancap.htm

India has centers for crash testing at the Automotive

Research Association of India (ARAI) and Society of

Indian Automobile Manufacturers (SIAM) in Bangalore.

Tata Motors’s is the only car maker in India that has a

crash-test facility located at huge plant in Pune established

in 1996.



CONCLUSION:

The safety deficits of cars observed in accident statistics

can be alleviated if the structures of these cars are designed

and optimized for the situation they will most likely

encounter in a real world situation.

One of the prime reasons for the alarming increase in

deaths due to accidents in India is that crash testing of

vehicles is not mandatory. Every carmaker emphasizes that

his make is better. But the consumer has to change his

approach and consider that car, which can best avoid

injuries to him in a crash.

Crash testing leads to improvement of the safety systems.

These systems again have to be tested for their workability

during a crash. Hence crash testing plays a vital role in

continuous improvement of the safety systems.

Design changes in vehicles like the crumple zones and the

location of engine block have been the results of evolution

of crash testing. Therefore in future, crash testing could

suggest many more design changes, which could further

minimize the probability of injury during a crash. Thus

crash testing make driving a more secure and reliable

experience.



Bibliography:

Wikipedia.

NDTV car n bike show.

http://www.tata.com/tata_motors/articles/index.htm

http://www.nhtsa.dot.gov/cars/testing/ncap/

http://www.globalncap.com/indiancarcrash results

Paper on Offset crash tests – Observations about vehicle

design and structural performance- by Michael Paine; Vehicle

Design and Research Pty Limited; Donald McGrane Crash

lab, NSW Roads and Traffic Authority; Jack Haley.

Impact simulation and full scale crash testing of a low profile

concrete work zone barrier (Gary R. Consolazio *, Jae H.

Chung, Kurtis R. Gurley)

Anthropomorphic Dummies for Crash andEscape System

Testing (Mannequins anthropometriques utilizes lors des tests d'

impacted dejection)

http://www.globalncap.com/indian

Car crash testing

Automotive

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