Car Crash Simulator.txt
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The lead car was programmed to unpredictably (to the driver) change speeds at variable intervals. The lead car traveled between 55 and 65 mph (with an average speed of 60 mph) with its speed determined by a sum of three sinusoids. The lead car was programmed to make 8 unpredictable (to the driver) full stops at a -6 m/s2. The behavior of the lead car made it very difficult for the driver to predict when the lead car would speed up, slow down, or stop; creating multiple possible rear-end collision situations. Intermittent opposing roadway traffic was included to more closely simulate real-world rural driving conditions. If the participant contacted the lead vehicle (i.e., crashed) an audio file of a crash sound was presented for a duration of 500 msec and lead vehicle disappeared from the screen.
Software lets engineers run crash tests inside computers rather than on roads. It also allows them to compare the performance of different designs early in the process while cars are still on the drawing board, saving money and injuries.
In 1976, John Hallquist at Lawrence Livermore National Laboratory (LLNL) created DYNA3D, which used the finite element method to measure the impact of nuclear bombs dropped at low altitudes. Its unique 3-D capabilities became the foundation for commercial software that simulated car crashes.
John Hallquist is the creator of the earliest crash test software, LS-DYNA (originally called DYNA3D). He left LLNL in 1987 to start his own company, Livermore Software Technology Corporation, and now holds over 15 patents for his work.
The earliest simulations produced pages of numerical data, which engineers had to interpret. Today, powerful computers turn this data into graphics, letting engineers watch moving images of car crashes, greatly simplifying their analysis of the results.
Since the 1950s, crash test dummies have evolved from a single dummy to entire families. Today, dummies represent different sizes, weights, and heights, providing engineers with more accurate results during crash tests.
Crash test dummies have been the subject of public service announcements, cartoons, parodies, even the name of a band. Real crash test dummies, however, are true life-savers as an integral part of automotive crash tests. Even though cars get a little safer each year, and fatality rates are declining, car crashes are still one of the leading causes of death and injury in the United States.
One of the reasons cars have been getting safer is because of a well-established testing program. In this article, you'll learn all about automotive crash testing, including crash test programs, ratings, dummies and future improvements. You'll be amazed at how much thought and preparation goes into making sure that safe cars are on the roads!
All frontal crash tests in the United States are conducted using the same type of dummy, the Hybrid III dummy. This guarantees consistent results. 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.
The dummies come in different sizes (click here to see some of the dummies), and they are referred to by percentile and gender. For example, the fiftieth-percentile male dummy represents the median sized male -- it is bigger than half the male population and smaller than the other half. This is the dummy most commonly used in crash testing. It weighs 170 lbs (77 kg) and is 70 inches (5 ft 10 inches or 1.78 m) tall.
The crash-test dummy has accelerometers all over it. 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 chest, pelvis, legs, feet and other parts of the body.
The graph above shows the acceleration of the driver's head during a 35 mph (56.3 kph) frontal crash. Notice that it is not a steady value, but fluctuates up and down during the crash. This reflects the way the head slows down during a crash, with the highest values coming when the head strikes hard objects or the airbag.
The scan above shows the driver's chest deflection during a crash. In this particular crash, the driver's chest is compressed about 2 inches (46 mm). This injury would be painful, but probably not fatal.
Before the crash-test dummies are placed in the vehicle, researchers apply paint to them. Different colors of paint are applied to the parts of the dummies' bodies most likely to hit during a crash. The dummy's knees, face and areas of the skull are each painted with a different color. In the following photo, you can see that the blue paint from the dummy's face is smeared on the airbag and that his left knee (painted red) hit the steering column.
If researchers note a particularly large acceleration in the data from the accelerometers in the dummy driver's head, 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 front passenger-side dummy's knees hit the dashboard during the crash. Also, note that nothing from the engine compartment penetrated the cabin. 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.
The photo below shows a van that is ready to crash. The dummies have been placed in the car and are in position. All of the instrumentation on the car and dummies has been hooked up and checked. Ballast is added to the car so that the crash-test vehicle's weight -- and the distribution of that weight -- is equal to that of a fully loaded vehicle. A speed sensor has been mounted to the car and positioned so that it will pass through a pickup just as the car hits the barrier.
There are 15 high-speed cameras, including several under the car pointed upward. They shoot around 1,000 frames per second. Next, the car is backed away from the barrier and prepared to crash. A pulley, mounted in a track, pulls the car down the runway. The car hits the barrier at 35 mph. It only takes about 0.1 seconds from the time the car hits the barrier until it stops.
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. How can all of the safety systems come together to give you the smoothest crash possible
Surviving a crash is all about kinetic energy. When your body is moving at 35 mph (56 kph), it has a certain amount of kinetic energy. After the crash, when you come to a complete stop, you will have zero kinetic energy. To minimize risk of injury, you would like to remove the kinetic energy as slowly and evenly as possible. Some of the safety systems in your car help do this.
In this hypothetical crash, the safety systems in the car all worked together to slow you down. If you didn't wear your seatbelt then the first stage of your protection is lost and it is going to hurt a lot more when you slam into the airbag. Many cars have seatbelt pretensioners and force limiters, but there are some even more exciting safety improvements coming.
The most recent advancement in safety equipment is known as a smart air bag. These air bags can deploy with different speeds and pressures, depending on the weight and seating position of the occupant, and also on the intensity of the crash.
Technology is enabling carmakers to design and manufacture safer, smarter vehicles, and consumers clearly endorse this trend as reflected in buying patterns. It may take wrecking lots of cars and crash test dummies, but the information gained from automotive crash tests means you and your loved ones may survive an automobile accident with little or no injury.
In recent years, cars have gotten much safer. One reason is that safety is now a selling point in new cars -- people actually seek out and buy safer cars. In the United States, the NHTSA crashes cars and analyzes data with a goal of improving car safety.
Carmakers themselves crash many vehicles each year. Car manufacturers are required to certify that their cars meet the Federal Motor Vehicle Safety Standards (FMVSS). These rules cover everything from how bright the turn signal bulbs must be to the crash-testing requirements. Carmakers have to be certain that if the NHTSA goes to any dealer in the United States, buys any car and crashes it at 30 mph, the car will pass all of the FMVSS requirements. To ensure that all of the different combinations of engines, transmissions and accessories will pass, carmakers might crash 60 to 100 vehicles themselves.
It is rare that a car fails the FMVSS requirements, so to challenge the carmakers even more -- and to provide valuable information to consumers buying cars -- the NHTSA started their New Car Assessment Program (NCAP). NCAP crashes cars at 35 mph (56 kph) in both frontal and side impact, and rates the cars based on how likely the occupants are to be injured during a crash. You can find the ratings online, a good first stop when looking for a new car.
This is a pretty tough question. In order to answer it, we have to define a serious injury. A lot of research has been done (and is still being done) to classify injuries. Crash-test researchers came up with a standard called the Abbreviated Injury Scale (AIS) for classifying different injuries. These same researchers published a manual that contains detailed descriptions of all the injuries normally found in car crashes. Each injury is assigned a rank based on how severe it was: 1 is just minor cuts and bruises; 3 indicates a serious injury that requires immediate medical treatment and may be life threatening; 6 is fatal.
Researchers have used crash test data to determine the likelihood of injuries that may be sustained in a crash. In addition, that data was used to create the NHTSA's star system. This system makes automobile safety ratings easier for consumers to understand when buying a car. 59ce067264