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Crash test dummy

2007 Schools Wikipedia Selection. Related subjects: Engineering

   Crash test dummies have saved countless lives.
   Crash test dummies have saved countless lives.

   Crash test dummies are full-scale replicas of human beings, weighted
   and articulated to simulate the behaviour of a human body in a
   motor-vehicle collision, and instrumented to record as much data as
   possible on variables such as speed of impact, crushing force, bending,
   folding, or torque of the body, and deceleration rates during a
   collision. In modern times, they remain indispensable in the
   development of new makes and models of all types of vehicles, from
   family sedans to fighter aircraft. This article focuses on the role of
   crash test dummies in preventing injury to automobile occupants.

The need for testing

   On August 31, 1869, Mary Ward became what is believed to be the first
   recorded victim of an automobile accident, when she was thrown out of a
   motor vehicle and killed in Parsonstown, Ireland. Some years later, on
   September 13, 1899, Henry Bliss entered the history books as North
   America's first motor vehicle fatality when he was hit stepping off a
   New York City trolley. Since that time, in excess of 20 million people
   worldwide have lost their lives to motor vehicle accidents.

   The need for a means of analysing and mitigating the effects of motor
   vehicle accidents on human bodies was felt very soon after the
   commercial production of automobiles began in the late 1890s, and by
   the 1930s, with the automobile a common part of daily life, the number
   of motor vehicle deaths was becoming a serious issue. Death rates had
   surpassed 15.6 fatalities per 100 million vehicle-miles and were
   continuing to climb; vehicle designers saw this as a clear indication
   it was time to do some research on ways to make their products safer.

   In 1930, the interior of a car was not a safe place even in a low-speed
   collision. Dashboards were made of rigid metal, steering columns were
   non-collapsible, and protruding knobs, buttons, and levers were
   ubiquitous. Seat belts were unheard-of, and in a frontal collision,
   passengers hurled through the windshield stood very little chance of
   avoiding serious injury or death. The vehicle body itself was rigid,
   and impact forces were transmitted directly to the vehicle occupants.
   As late as the 1950s, car manufacturers were on public record as saying
   vehicle accidents simply could not be made survivable; the forces in a
   crash were too great and the human body too frail.

Cadaver testing

   Detroit's Wayne State University was the first to begin serious work on
   collecting data on the effects of high-speed collisions on the human
   body. In the late 1930s, there were no reliable data on the response of
   the human body to extreme physical insult, and no effective tools
   existed to measure such responses. Biomechanics was a field barely in
   its infancy. It was therefore necessary to employ two types of test
   subjects in order to develop initial data sets.

   The first test subjects were human cadavers. They were used to obtain
   fundamental information about the human body's ability to withstand the
   crushing and tearing forces typically experienced in a high-speed
   accident. To such an end, steel ball bearings were dropped on skulls,
   and bodies were dumped down unused elevator shafts onto steel plates.
   Cadavers fitted with crude accelerometers were strapped into
   automobiles and subjected to head-on collisions and vehicle rollovers.

   Albert King's 1995 Journal of Trauma article, "Humanitarian Benefits of
   Cadaver Research on Injury Prevention", clearly states the value in
   human lives saved as a result of cadaver research. King's calculations
   indicate that as a result of design changes implemented up to 1987,
   cadaver research has since saved 8500 lives annually. He notes that for
   every cadaver used, each year 61 people survive due to wearing seat
   belts, 147 live due to air bags, and 68 survive windshield impact.

   However, work with cadavers presented almost as many problems as it
   resolved. Not only were there the moral and ethical issues related to
   working with the dead, but there were also research concerns. The
   majority of cadavers available were older Caucasian adults who had died
   non-violent deaths; they did not represent a demographic cross-section
   of accident victims. Deceased accident victims could not be employed
   because any data that might be collected from such experimental
   subjects would be compromised by the cadaver's previous injuries. Since
   no two cadavers are the same, and since any specific part of a cadaver
   could be used only once, it was extremely difficult to achieve reliable
   comparison data. In addition, child cadavers were not only difficult to
   obtain, but both legal and public opinion made them effectively
   unusable. Moreover, as crash testing became more routine, suitable
   cadavers became increasingly scarce. As a result, biometric data were
   limited in extent and skewed toward the older white male.

Volunteer testing

   Some researchers took it upon themselves to serve as crash test
   subjects. Colonel John Paul Stapp USAF propelled himself over 630 mph
   (1010 km/h) on a rocket sled and stopped in less than a second.
   Lawrence Patrick, a now-retired Wayne State University professor,
   endured some 400 rides on a rocket sled in order to test the effects of
   rapid deceleration on the human body. He and his students allowed
   themselves to be smashed in the chest with heavy metal pendulums,
   impacted in the face by pneumatically-driven rotary hammers, and
   sprayed with shattered glass to simulate window implosion. While
   admitting that it made him "a little sore," Patrick has said that the
   research he and his students conducted was seminal in developing
   mathematical models against which further research could be compared.
   But while data from live testing was valuable, human subjects could not
   withstand tests which went past a certain degree of physical
   discomfort. To gather information about the causes and prevention of
   injuries and fatalities would require a different kind of subject.

Animal testing

   By the mid-1950s, the bulk of the information cadaver testing could
   provide had been harvested. It was also necessary to collect data on
   accident survivability, research for which cadavers were woefully
   inadequate. In concert with the shortage of cadavers, this need forced
   researchers to seek other models. A description by Mary Roach of the
   Eighth Stapp Car Crash and Field Demonstration Conference shows the
   direction in which research had begun to move. "We saw chimpanzees
   riding rocket sleds, a bear on an impact swing...We observed a pig,
   anesthetized and placed in a sitting position on the swing in the
   harness, crashed into a deep-dish steering wheel at about 10 mph."

   One important research objective which could not be achieved with
   either cadavers or live humans was a means of reducing the injuries
   caused by impalement on the steering column. By 1964, over a million
   fatalities resulting from steering wheel impact had been recorded, a
   significant percentage of all fatalities; the introduction by General
   Motors in the early 1960s of the collapsible steering column cut the
   risk of steering-wheel death by fifty percent. The most commonly used
   animal subjects in cabin-collision studies were pigs, primarily because
   their internal structure is similar to a human's. Pigs can also be
   placed in a vehicle in a good approximation of a seated human.

   The ability to sit upright was an important requirement for test
   animals in order that another common fatal injury among human victims,
   decapitation, could be studied. As well, it was important for
   researchers to be able to determine to what extent cabin design needed
   to be modified to ensure optimal survival circumstances. For instance,
   a dashboard with too little padding or padding which was too stiff or
   too soft would not significantly reduce head injury over a dash with no
   padding at all. While knobs, levers, and buttons are essential in the
   operation of a vehicle, which design modifications would best ensure
   that these elements did not tear or puncture victims in a crash?
   Rear-view mirror impact is a significant occurrence in a frontal
   collision; how should a mirror be built so that it is both rigid enough
   to perform its task and yet of low injury risk if struck?

   While work with cadavers had aroused some opposition, primarily from
   religious institutions, it was grudgingly accepted because the dead,
   being dead, felt no pain, and the indignity of their situations was
   directly related to easing the pain of the living. Animal research, on
   the other hand, aroused much greater passion. Animal rights groups such
   as the ASPCA were vehement in their protest, and while researchers such
   as Patrick supported animal testing because of its ability to produce
   reliable, applicable data, there was nonetheless a strong ethical
   unease about this process.

   Although animal test data were still more easily obtained than cadaver
   data, the fact that animals were not people and the difficulty of
   employing adequate internal instrumentation limited their usefulness.
   Animal testing is no longer practiced by any of the major automobile
   makers; General Motors discontinued live testing in 1993 and other
   manufacturers followed suit shortly thereafter.

Dummy evolution

   Sierra Sam tested ejection seats.
   Enlarge
   Sierra Sam tested ejection seats.

   The information gleaned from cadaver research and animal studies had
   already been put to some use in the construction of human simulacra as
   early as 1949, when "Sierra Sam" was created by Samuel W. Alderson at
   his Alderson Research Labs (ARL) and Sierra Engineering Co. to test
   aircraft ejection seats and pilot restraint harnesses. This testing
   involved the use of high acceleration to 1000 km/h (600 mph) rocket
   sleds, beyond the capability of human volunteers to tolerate. In the
   early 1950s, Alderson and Grumman produced a dummy which was used to
   conduct crash tests in both motor vehicles and aircraft.
   The mass production of dummies afforded their use in many more
   applications.
   Enlarge
   The mass production of dummies afforded their use in many more
   applications.

   Alderson went on to produce what it called the VIP-50 series, built
   specifically for General Motors and Ford, but which was also adopted by
   the National Bureau of Standards. Sierra followed up with a competitor
   dummy, a model it called "Sierra Stan," but GM, who had taken over the
   impetus in developing a reliable and durable dummy, found neither model
   satisfied its needs. GM engineers decided to combine the best features
   of the VIP series and Sierra Stan, and so in 1971 Hybrid I was born.
   Hybrid I was what is known as a "50th percentile male" dummy. That is
   to say, it modeled an average male in height, mass, and proportion. The
   original "Sierra Sam" was a 95th percentile male dummy (heavier and
   taller than 95% of human males). In cooperation with the Society of
   Automotive Engineers (SAE), GM shared this design, and a subsequent 5th
   percentile female dummy, with its competitors.

   Since then, considerable work has gone into creating more and more
   sophisticated dummies. Hybrid II was introduced in 1972, with improved
   shoulder, spine, and knee responses, and more rigorous documentation.
   Hybrid II became the first dummy to comply with the American Federal
   Motor Vehicle Safety Standard (FMVSS) for testing of automotive lap and
   shoulder belts. In 1973, a 50th percentile male dummy was released, and
   the National Highway Transportation Safety Administration (NHTSA) NHTSA
   undertook an agreement with General Motors to produce a model exceeding
   Hybrid II's performance in a number of specific areas.

   Though a great improvement over cadavers for standardized testing
   purposes, Hybrid I and Hybrid II were still very crude, and their use
   was limited to developing and testing seat belt designs. A dummy was
   needed which would allow researchers to explore injury-reduction
   strategies. It was this need that pushed GM researchers to develop the
   current Hybrid line, the Hybrid III family of crash test dummies.

Hybrid III family

   The original 50th percentile male Hybrid III's family expanded to
   include a 95th percentile male, 5th percentile female, and
   three-year-old and six-year-old child dummies.
   Enlarge
   The original 50th percentile male Hybrid III's family expanded to
   include a 95th percentile male, 5th percentile female, and
   three-year-old and six-year-old child dummies.

   Hybrid III, the 50th percentile male dummy which made its first
   appearance in 1976, is the familiar crash test dummy, and he is now a
   family man. If he could stand upright, he would be 168 cm (5 '6 ") tall
   and would have a mass of 77 kg (170 lb). He occupies the driver's seat
   in all the Insurance Institute for Highway Safety (IIHS) 65 km/h (40
   mph) offset frontal crash tests. He is joined by a "big brother", the
   95th percentile Hybrid III, at 188 cm (6 ft 2 in) and 100 kg (223 lb).
   Ms. Hybrid III is a 5th percentile female dummy, at a diminutive 152 cm
   (5 ft) tall and 50 kg (110 lb). The two Hybrid III child dummies
   represent a 21 kg (47 lb) six year old and a 15 kg (33 lb) three year
   old. The child models are very recent additions to the crash test dummy
   family; because so little hard data are available on the effects of
   accidents on children, and such data are very difficult to obtain,
   these models are based in large part on estimates and approximations.

Test process

   Every Hybrid III undergoes calibration prior to a crash test. Its head
   is removed and is dropped from 40 centimetres to test calibrate the
   head instrumentation. Then the head and neck are reattached, set in
   motion, and stopped abruptly to check for proper neck flexure. Hybrids
   wear chamois leather skin; the knees are struck with a metal probe to
   check for proper puncture. Finally, the head and neck are attached to
   the body, which is attached to a test platform and struck violently in
   the chest by a heavy pendulum to ensure that the ribs bend and flex as
   they should.

   When the dummy has been determined to be ready for testing, it is
   dressed entirely in yellow, marking paint is applied to the head and
   knees, and calibration marks are fastened to the side of the head to
   aid researchers when slow-motion films are reviewed later. The dummy is
   then placed inside the test vehicle. Forty-four data channels located
   in all parts of the Hybrid III, from the head to the ankle, record
   between 30 000 and 35 000 data items in a typical 100 - 150
   millisecond crash. Recorded in a temporary data repository in the
   dummy's chest, these data are downloaded to computer once the test is
   complete.

   Because the Hybrid is a standardized data collection device, any part
   of a particular Hybrid type is interchangeable with any other. Not only
   can one dummy be tested several times, but if a part should fail, it
   can be replaced with a new part. A fully-instrumented dummy is worth
   about €150 000.

Hybrid's successors

   Hybrid IIIs are designed to research the effects of frontal impacts,
   and are less valuable in assessing the effects of other sorts of
   impacts, such as side impacts, rear impacts, or rollovers. After
   head-on collisions, the most common severe injury accident is the side
   impact.

   The SID (Side Impact Dummy) family of test dummies has been designed to
   measure rib, spine, and internal organ effects in side collisions. It
   also assesses spine and rib deceleration and compression of the chest
   cavity. SID is the US government testing standard, EuroSID is used in
   Europe to ensure compliance with safety standards, and SID II(s)
   represents a 5th percentile female. BioSID is a more sophisticated
   version of SID and EuroSID, but is not used in a regulatory capacity.

   BioRID is a dummy designed to assess the effects of a rear impact. Its
   primary purpose is to research Whiplash, and to aid designers in
   developing effective head and neck restraints. BioRID is more
   sophisticated in its spinal construction than Hybrid; 24 vertebra
   simulators allow BioRID to assume a much more natural seating posture,
   and to demonstrate the neck movement and configuration seen in rear-end
   collisions.

   CRABI is a child dummy used to evaluate the effectiveness of child
   restraint devices including seat belts and air bags. There are three
   models of the CRABI, representing 18-month, 12-month, and 6-month old
   children.

   THOR is an advanced 50th percentile male dummy. The successor of Hybrid
   III, THOR has a more humanlike spine and pelvis, and its face contains
   a number of sensors which allow analysis of facial impacts to an
   accuracy currently unobtainable with other dummies. THOR's range of
   sensors is also greater in quantity and sensitivity than those of
   Hybrid III.
   THOR offers sophisticated instrumentation for assessing
   frontal-impacts.
   Enlarge
   THOR offers sophisticated instrumentation for assessing
   frontal-impacts.

   Further development is needed on dummies which can address the concern
   that, even though fewer lives are lost, there are still a hundred
   seriously injured passengers for every death, and crippling injuries to
   the legs and feet represent a great percentage of resultant physical
   impairments.

Future of the dummy

   Crash test dummies have provided invaluable data on how human bodies
   react in crashes and have contributed greatly to improved vehicle
   design. While they have saved millions of lives, like cadavers and
   animals, they have reached a point of reduced data return.

   The largest problem with acquiring data from cadavers, other than their
   availability, was that an essential element of standardized testing,
   repeatability, was impossible. No matter how many elements from a
   previous test could be reused, the cadaver had to be different each
   time. While modern test dummies have overcome this problem, testers
   still face essentially the same problem when it comes to testing the
   vehicle. A vehicle can be crashed only once; no matter how carefully
   the test is done, it cannot be repeated exactly.

   A second problem with dummies is that they are only approximately
   human. Forty-four data channels on a Hybrid III is not even a remote
   representation of the number of data channels in a living person. The
   mimicking of internal organs is crude at best, a fact that means that
   even though cadavers and animals are no longer the primary sources of
   accident data, they must still be employed in the study of soft tissue
   injury.

   The future of crash testing has begun at the same place it all started:
   Wayne State University. King H. Yang is one of Wayne State's
   researchers involved in creating detailed computer models of human
   systems. Currently, computers are neither fast enough nor programmers
   skilled enough to create full-body simulations, but injury analysis of
   individual body systems is producing reliable and encouraging results.

   The advantage of the computer is that it is unbound by physical law. A
   virtual vehicle crashed once can be uncrashed and then crashed again in
   a slightly different manner. A virtual back broken can be unbroken, the
   seatbelt configuration changed, and the back re-broken. When every
   variable is controllable and every event is repeatable, the need for
   physical experimentation is greatly reduced.

   At the beginning of the 21st century, legal certification of new car
   models is still required to be done using physical dummies in physical
   vehicles. However, the future is almost certainly one where neither
   skin and bone, or plastic and steel will determine the shape of
   vehicles to come. The next generation of crash test dummies will
   perform their tasks entirely on a computer screen.

Popular culture

   Vince and Larry
   Enlarge
   Vince and Larry

   The humanoid appearance of crash test dummies led to their becoming
   anthropomorphized.

   In the 1980s, the US Department of Transportation launched a series of
   public service announcements in magazines and on television featuring
   the antics of two talking crash dummies named Vince and Larry ( Jack
   Burns and Lorenzo Music) who modeled seat belt safety practices through
   their slapstick antics. The campaign, with its slogan "You can Learn a
   Lot from a Dummy," was very popular, and since then crash dummy
   characters remain a common sight in seat belt safety campaigns,
   especially those aimed at children.

   In the early 1990s, Tyco Toys created a line of action figures called
   The Incredible Crash Dummies based on the characters from the ads. The
   colorful toys were intended to fall apart at the touch of a button on
   their stomachs and could easily be re-assembled. Vehicles could also be
   bought, which could similarly be crashed into walls and broken, and
   easily put back together.

   The Incredible Crash Dummies line of toys featured characters such as
   Slick and Spin, the main duo, and their friends, Darryl, Spare Tire,
   and Bull. Later on, the villainous Junk Bots were introduced.

   The popularity of the toys prompted a one-hour television special, The
   Adventures of the Incredible Crash Dummies. Unique for its time, the
   cartoon was produced entirely using 3D computer animation techniques. A
   comic book series was also produced as well as a video game for the
   Nintendo Entertainment System.

   Rumors say that due to complaints from some parents groups against the
   "violence" inherent in the toys, the series was discontinued. A more
   likely explanation is that Tyco Toys was dissolved in 2001.

   In 2004, a series of "Crash Dummies" animated shorts were commissioned
   for the FOX network, thus spawning another series of toys from Mattel
   through the Hot Wheels brand.

   The television series MythBusters employs a crash test dummy for
   experiments that are too risky for the human hosts to try. " Buster"
   has tested, among other things, the dynamics of falling elevators,
   drops into water, getting a foot stuck in a washing machine, getting
   shot out of a drainage culvert, improper use of construction equipment
   and ancient attempts at space flight. Buster was redesigned in the
   second season of the show, giving him more realistic joints, easily
   replaceable wooden bones that break at the same force as human bones,
   and fire-proof molded silicone rubber skin.

   In Discovery kids' childrens' educational series Crash Test Danny the
   title character is a living breathing crash test dummy played by Ben
   Langley who gets crushed, exploded and pulled apart all in the name of
   science.

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