CAR CRASH TESTING

CAR CRASH TESTING01FM14EAT011 KUMAR MANIKANTAN T

ABSTRACTDriving 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)

DUMMIESCrash 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'sAccelerometers: - 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 testAt 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 TestIn 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 cars 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 ENERGYObviously 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 carAs 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 vehicleThe 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

Ratings for Side-Impact Tests# Of StarsResult55% or lower chance of serious injury46% to 10% chance of serious injury311% to 20% chance of serious injury221% to 25% chance of serious injury126% or greater chance of serious injury

CRASH TEST RATINGS OF THE CARS (Probability of injuries)Ratings for Frontal-Impact Tests# Of StarsResult510% or lower chance of serious injury411% to 20% chance of serious injury321% to 35% chance of serious injury236% to 45% chance of serious injury146% or greater chance of serious injuryRatings for Side-Impact Tests# Of StarsResult55% or lower chance of serious injury46% to 10% chance of serious injury311% to 20% chance of serious injury221% to 25% chance of serious injury126% or greater chance of serious injuryWhere does the popular Indian cars stand in Global market?According to recent test conducted on Indias 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.

ConclusionThe 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.

Thank you..!