Car crash testing

CAR CRASH TESTING
01FM14EAT011 KUMAR MANIKANTAN T

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.

Infrastructural need for Crash Test
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.

Have you ever wondered how car
crash tests are conducted?
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.
WINCH : lifting device consisting of a rope
or chain winding round a horizontal rotating
drum, turned typically by a crank or by
motor.

Impact of Car to Car
It is made to pull with the vehicle wire and to run two at the
same time, and the vehicle is made to collide with the vehicle.
It is possible to adjust to new standard by which the energy-absorption
when the car with a different size collides
mutually is evaluated and "Compatibility" (The NHTSA
advocates it)

DUMMIE’S
Crash test dummies are the key as they are
used as replica for human 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.

Major parts in Dummy's
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 which part of
the body got collided with vehicle inside the cabin. This information
helps researchers develop improvements to prevent that type of injury
in future crashes.

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 Testing

Frontal crash test
At 35 mph (56 kmph), 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

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.

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 (Probability of injuries)
 Ratings for Side-Impact Tests
Ratings for Frontal-Impact Tests
 # Of Stars
 Result
# Of
Stars
Result
 5
 5% or lower chance of serious injury
 4
5 10% or lower chance of serious injury
 6% to 10% chance of serious injury
 3
4 11% to 20% chance of serious injury
 2
 1
 26% or greater chance of serious injury
1
46% or greater chance of serious
injury
Ratings 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

Where does the popular Indian cars
stand in Global market…………?
According to recent test
conducted on India’s most
popular cars from
different manufacturer by
the Global NCAP and
Institute of road traffic
education (IRT).
Where all the tested were
on entry level variables
but there was only a
disturbing results….

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.

Car crash testing

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