Airbag Crash Test Dummy
Shanta Plansinis
This example shows how to model an automotive crash test with front seat crash dummy. The model uses virtual reality animation to visualize the results (optional). This example was translated from the MathWorks shipping demo to utilize the newer SimMechanics 2G technology.
An average adult female crash test dummy simply does not exist, despite the fact that women obviously drive to work, take road trips, and ride in cars with friends, and even though female bodies react differently from male bodies in crashes. That absence has set the course for four decades' worth of car safety design, with deadly consequences.
Although the majority of Americans killed or injured in car crashes are male, the raw data masks the fact that females are actually at greater risk of death or injury when a crash occurs. Data from the National Highway Traffic Safety Administration and the Federal Highway Administration (FHWA) shows that males drive more miles than females, and are more likely to engage in risky behavior, such as speeding, driving under the influence of alcohol, and not wearing a seat belt. But a study from NHTSA shows that a female driver or front passenger who is wearing her seat belt is 17 percent more likely than a male to be killed when a crash takes place. And a 2019 study from the University of Virginia (UVA) shows that for a female occupant, the odds of being injured in a frontal crash are 73 percent greater than the odds for a male occupant. That's controlling for occupant age, height, and body mass index, in addition to collision severity and vehicle model year.
These alarming numbers suggest an urgent safety issue, but the problem is neither new nor unfamiliar to regulators and automakers. "These same trends have been observed in many, many studies in the past," says Jason Forman, Ph.D., who is a principal scientist with the Center for Applied Biomechanics at UVA and led that 2019 survey of injury disparities.
In frontal crash tests performed for both NHTSA and the Insurance Institute for Highway Safety, this 5th percentile female dummy either rides as a passenger or doesn't participate in the test at all. (The female dummy sits in the driver's seat for some side-impact tests.) This, despite the fact that women now represent almost 50 percent of drivers in the U.S., according to the FHWA.
Because automotive design is directly influenced by the results of safety testing, any bias in the way cars are crash-tested translates into the way cars are manufactured. So if safety tests don't prioritize female occupants, carmakers won't necessarily make changes to better protect them.
"The reality of progress in automotive safety is that it heavily relies on regulation," says Emily Thomas, Ph.D., automotive safety engineer at Consumer Reports' Auto Test Center. "Unless the federal motor vehicle safety standards require dynamic crash testing with average-sized female crash dummies in multiple seating positions, driver side included, the dummy industry and automakers won't make that leap themselves."
According to Consumer Reports' Thomas, the crash energy that isn't absorbed by the vehicle in that first stage is then transferred to the occupants. "Vehicle restraint systems, like seat belts and airbags, are intended to limit motion and that transfer of energy," she says. "But to do that effectively across a range of body types, carmakers and crash testers need to consider not just the size of different occupants but also the material properties of their bodies."
According to the Centers for Disease Control and Prevention, today's average female is 5.4 inches shorter and 27 pounds lighter than the average male. As a result, females may sit closer to the steering wheel or wear their seatbelts differently from males. But differences aren't just about shape, size, and position. For example, the female pelvis has a geometry that's different from the male pelvis, and the male neck is stronger when it comes to forces that bend it.
Even the internal makeup of female bones can be different from that of male bones. Because crash injuries and fatalities are often related to bone fractures, this may explain some of the disparities between the sexes.
"People assume that bone is this dead, static structure in your body, but it's definitely not," says Mandy Agnew, Ph.D., a biological anthropologist and director of the Skeletal Biology Research Lab at the Ohio State University Injury Biomechanics Research Center. "It's sensing loads constantly and altering its size and shape to meet those needs, so it's quite dynamic."
Consider whiplash. Females are up to three times more likely to suffer whiplash injuries than males, but real-world crash data shows many vehicle seats that have been specifically designed to prevent whiplash injuries are actually less likely to help female occupants.
In the late 1990s, automakers developed two kinds of safety systems designed to protect against whiplash. One, used primarily by Volvo, is designed to absorb crash energy in the seatback and head restraint. It reduced life-altering whiplash injuries for both male and female occupants but proved to be slightly more effective for females. (Toyota uses a similar design.) The other design, used by many other manufacturers, uses only a moving head restraint to diminish the movement of the head and neck in rear impacts. While it reduces life-altering whiplash crash injuries up to 70 percent for male occupants, it has no benefit for females.
It's an open secret in the automotive industry that automakers engineer their cars specifically to pass crash tests. That's why it's critical for tests to represent how cars are used in the real world.
"When regulators or testing organizations set a new bar for crash safety, most automakers quickly change their designs so their cars ace the new test," says David Friedman, vice president of advocacy at Consumer Reports and a former NHTSA administrator.
That's what happened in 2012, when the IIHS, an independent crash testing agency funded by insurance companies, added a new evaluation, the small-overlap test. The test simulates a crash where the front driver-side corner of a vehicle collides with another vehicle or a tree or utility pole. As soon as the test was announced, some automakers began redesigning the next generation of vehicles to score well by improving vehicle structures and airbags. But those changes were made only to the driver's side of the vehicle, where that test was targeted. Similar improvements were not made to the passenger's side, prompting the IIHS to introduce a passenger-side version of the test in late 2017.
The results are remarkable: Only 3 out of the 11 cars initially tested in the 2012 model year received a score of Good or Acceptable. But for the current model year, every one of those cars now gets a Good or Acceptable score, thanks to redesign efforts.
"The problem today is that most car companies design to the test, and no further," he says. Friedman believes that regimented, overly predictable testing leads to engineering that simply checks boxes, rather than a more holistic approach to safety design. "That's why the next generation of crash tests needs to include more representative dummies and some randomness, putting different dummies in different seats across the tests. Then automakers would finally have to protect everyone equally."
The agency's use of 5th percentile female and 50th percentile male dummies represents "a broad spectrum of occupant crash protection rather than merely focusing on median body types," its statement said. "Currently, NHTSA is focusing its research in new advancements in both sizes of crash test dummies, including the use of advanced instrumentation and criteria designed to better mitigate respective injury risks."
The Auto Alliance, a trade group that represents many large automakers in the U.S., told CR that the group does not believe that a 50th percentile female dummy would be useful, especially because the average American female of 2019 is actually closer in height and weight to the current 50th percentile male dummy.
"So far we've not seen any data or analysis that suggests that the addition of a new [dummy] this close in weight to the existing one used in regulations, would significantly change any real-world restraint system designs," Wade Newton, a spokesman for the group, wrote in an email.
That research led directly to the development of some of the first crash test dummies. One of Patrick's students, Harold Mertz, led the team at General Motors that created the first version of the average male automotive crash test dummy we still use today, which originally debuted in 1976. The modern version, called the Hybrid III, is used in crash tests currently conducted by NHTSA and the IIHS.
Two years after that first dummy debuted, NHTSA started its New Car Assessment Program (NCAP) during the Carter administration. Although similar programs now exist worldwide, the program was revolutionary when it first began. It was the first time a government agency had ever crash-tested cars, rated them for safety, and released those ratings to the public. According to Joan Claybrook, who was NHTSA's administrator at the time, the agency started with male crash test dummies because the agency had limited funds and because men were the ones dying in crashes. "It was just that men were in the workplace, and they were more likely to be in car crashes," she says.
At the time, the agency took an expansive approach to regulation. Under Claybrook, who had worked previously with consumer advocate Ralph Nader, NHTSA proposed a number of safety rules, including mandatory airbags and tire pressure monitoring sensors. (From 1982 to 2006, Claybrook also served on the board of Consumers Union, as CR's publisher was then known.)
Claybrook blames shifting attitudes toward regulation and the role of government for the stalling of many automotive safety efforts, including the development of new crash test dummies, in the early 1980s.
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