A crash test dummy is a full-scale anthropomorphic test device (ATD) that simulates the dimensions, weight proportions and articulation of the human body, and is usually instrumented to record data about the dynamic behavior of the ATD in simulated vehicle impacts. The Crash Test Dummy is widely used by researchers and automobile companies to predict the biomechanics, force, impact, and injury of a human being in an automobile crash. This data can include variables such as velocity of impact, crushing force, bending, folding, or torque of the body, and deceleration rates during a collision for use in crash tests. The more advanced dummies are sophisticated machines designed to behave as a human body and with many sensors to record the forces of an impact; they may cost over US$400,000.
For the purpose of U.S. regulation and Global Technical Regulations and for clear communication in safety and seating design, dummies carry specifically designated reference points, such as the H-point; these are also used, for example, in automotive design.
Crash test dummies remain indispensable in the development of and ergonomics in all types of vehicles, from automobiles to aircraft.
There are many specialized dummies used for obesity, children, rib impact, and spinal impact. THOR is a very advanced dummy because it uses sensors and has a humanlike spine and pelvis. Special classes of dummies called Hybrid IIIs are designed to research the effects of frontal impacts, and are less useful in assessing the effects of other types of impact, such as side impacts, rear impacts, or rollovers. Hybrid IIIs use dummies that directed towards a specific age, for example, a typical ten year old, six year old, three year old, and a grown man.
There are certain testing procedures for Hybrid IIIs to ensure that they obtain a correct humanlike neck flexure, and to ensure that they would react to a crash in a similar way that human bodies would. Using cadavers for these topics of research is more realistic than using a dummy for physiologic reasons, but it arises many moral dilemmas.
Going across a moral ethics line, automobile companies have used a human cadaver, a pig, and people have volunteered to be tested upon impact. A pig was used specifically for steering wheel impact because they have an internal structure similar to humans, and can be easily placed correctly via sitting up right in the vehicle. Human cadavers along with animals are not personally able to give consent to research studies, although animal testing is not prevalent today.
There are studies that use specific cadavers including obese cadavers, and children cadavers. Also, studies show how cadavers have been used to modify different parts of a car such as the seatbelt Each new car that is made provides a different structural impact which provides the conclusion that cadavers and crash test dummies will be useful for a long time.
Video Crash test dummy
History
On August 31, 1869, Mary Ward became the first recorded victim of an automobile accident; the car involved was steam-powered (Karl Benz did not invent the gasoline-powered automobile until 1886). Ward, of Parsonstown, Ireland, was thrown out of a motor vehicle and killed. Thirty years later, on September 13, 1899, Henry Bliss became North America's first motor vehicle fatality when hit while stepping off a New York City trolley. Since then, over 20 million people worldwide have died due to motor vehicle accidents.
The need for a means of analyzing and mitigating the effects of motor vehicle accidents on humans was felt soon after commercial production of automobiles began in the late 1890s, and by the 1930s, when the automobile became a common part of daily life and the number of motor vehicle deaths were rising. Death rates had surpassed 15.6 fatalities per 100 million vehicle-miles and were continuing to climb.
In 1930 cars had dashboards of rigid metal, non-collapsible steering columns, and protruding knobs, buttons, and levers. Without seat belts, passengers in a frontal collision could be hurled against the interior of the automobile or through the windshield. 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 that vehicle accidents simply could not be made survivable because the forces in a crash were too great.
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 was no reliable data on how the human body responds to the sudden, violent forces acting on it in an automobile accident. Furthermore, 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 since saved 8,500 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 white 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 only be used 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 males.
Very little attention has been paid to obesity and car crash studies, and it is hard to obtain an obese dummy for the experiment. Instead, human cadavers were used. Body weight is a vital factor when it comes to automobile accidents, and body mass is distributed differently in an obese person versus a non-obese person. At the University of Michigan, obese cadavers were tested and compared to non-obese cadavers, and they found that the obese cadavers had more injuries in their lower extremities. The researchers also suggested that an obese person could be protected by their fat almost causing a "cushioning effect."
The use of NDTs or Neutral Density Targets were implemented inside Cadavers brains to focus on the impact and separation of the brain and skull. NDTs provided detailed observations and allowed researchers to look at a specific area of the brain after the crash stimulation. It also helped to establish and develop the FE model. To measure neck injuries for three year olds, the model FE was created. A real child's neck was interpreted and incorporated into the FE model. There are only a few FE models and they were mostly utilized through sled tests.
Volunteer testing
Some researchers took it upon themselves to serve as crash test dummies. Colonel John Paul Stapp USAF propelled himself over 1000 km/h on a rocket sled and stopped in 1.4 seconds. Lawrence Patrick, then a professor at Wayne State University, 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 injury. 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. Additionally, 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. Researchers at the University of Virginia have to call the cadaver's family and tell them what they are using their loved one for, after getting consent from the family. This seems to lessen ethical dilemmas in contrast to animal testing, because there is no sufficient way to get consent to use an animal.
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.
In 1980, the use of animals such as bears and pigs were tested in car stimulation crashes. This led to moral dilemmas and was not the first time that animals were used in car crashes. In 1978, The University of Michigan Highway Safety Research Institute used baboons to be tested as a substitute for humans in car crashes. Although there was the objection of animal cruelty that arose, there was also the controversy of how they are similar to humans and can be used as a sufficient testing substitution for us. The researchers did not end up stopping the use of baboons because of moral objections, but instead stopped because they found sufficient data. The moral inputs from other people and organizations were inconsistent, which caused implications when deciding to ban healthy animals from research testing. The animals were put under anesthesia, so there was no pain put upon them, but the aftereffects can not justify this. The General Motors corporation used animals for testing, and also suggested that they put the animals under anesthesia and then would kill the animals after the testing is complete.
Although the University of Michigan Highway Safety Research Institute did get bad publicity, it was suggested that this is not the reason why they stopped using baboons. The University of Michigan's mission was to create safer cars for human use. In order to reach this goal, research and testing is inevitable. The cruelty and the moral dilemmas of animal testing did not trump researchers still using them as subjects. They reasoned that biomechanics data is needed for an experiment like this, which will lead to safer cars. Years later animal testing ceased and instead an instrumental dummy was created for replacement. In 1978, animals were their only source of subject that would be a reliable substitution to the human being. The disadvantage though to using an instrumental dummy or a human cadaver, is that the tissue is not alive and will not elicit the same response as, for an example, a live animal. Today, it is not common to see animals being tested upon for automobile accidents because of the advance in computers and technology. It is, although, difficult to use cadavers instead of animals because of human rights, and it is difficult to obtain permission from the families, especially with children. Consent for a research and testing can occur only if the person responsible for giving consent is a competent person and one who also comprehends the research and testing procedures fully.
Maps Crash test dummy
Dummy evolution
Sierra Sam and VIP-50
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, aviation helmets 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 original "Sierra Sam" was a 95th percentile male dummy (heavier and taller than 95% of human males).
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".
Hybrid I and II
General Motors, who had taken over the impetus in developing a reliable and durable dummy, found neither Sierra 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. 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) 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
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 175 cm (5'9") 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 three Hybrid III child dummies represent a ten-year-old, 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. The primary benefit provided by the Hybrid III is improved neck response in forward flexion and head rotation that better simulates the human.
The Hybrid III dummy for three-, six- and ten-year olds has its implications, and does not provide the same physical outcome a human would encounter with a frontal crash. It was found that when testing the three-year old Hybrid III dummy, it showed that frontal crashes would most likely cause cervical spine injuries. When using data from the real world, the results did not match up to the Hybrid III stimulation injuries. To get around this, THUMS was created which stands for Total Human Model of Safety. The model can be easily relatable to the human body anatomically especially focusing on the human spine upon impact. Clinical testing and experiments are more accurate than a dummy and more reliable case studies can be implemented with this model. The model is based on a male only, and mimics human tissues and organs. This model is accurate for males in the 50th percentile, and it can not easily relate to three-year olds when dealing with neck and head injuries which are responsible for 57 percent of car crash fatalities. Instead, the FE model can be appropriately implemented for this criteria.
Testing procedure
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, 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, set to seating position and then marked on either the head and knees. Up to fifty-eight 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 EUR150,000.
Positioning and restraints
Children in the three-year old age group are more likely to have a fatality because it is the age where positioning is crucial. In some countries, children transition from facing the rear of the car to facing the front at this age. A study was done on restraints and positioning of three-year olds. It was concluded that being restrained and in the front seat has a lower fatality rate than children positioned in the back seat but not restrained. The safety results indicated that children should be placed in the back seat and restrained. It also suggests that restraints have a bigger impact on safety than seating positions. A lap belt used on children will not provide as much safety as it would for an adult, due to the flexibility of children. An adult seatbelt could do more harm to a child than good, which is why children should properly be utilizing the Child Restraint System instead. This system includes a booster seat and a proper belt that fits the child's criteria including age, weight and height.
Specialized dummies
Hybrid IIIs are designed to research the effects of frontal impacts, and are less useful in assessing the effects of other types of impact, 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 is 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 United States 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. The WorldSID is a project to develop a new generation of dummy under the International Organization for Standardization.
- 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.
- FGOA is a first generation obese anthropometric test device which can be used to study the automotive safety challenges for obese occupants, who are believed to have higher risk of mortality in automobile collisions comparing to non-obese occupants.
- THOR is an advanced 50th percentile male dummy. The successor of Hybrid III, THOR has a more human-like 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's original manufacturer, GESAC Inc., ceased production after the slowdown of the auto industry in the late 2000s. THOR was being further developed, and two other companies were working on similar dummies; NHTSA's ultimate goal for this government-funded project was the development of a single THOR dummy, but THOR dummy development stopped. FTSS, bought by Humanetics, and DentonATD both continued to produce the THOR LX and THOR FLX.
- Animal models have been used to test the safety of dog harnesses and crates in crash conditions.
Popular culture
- In the 1980s the National Highway Traffic Safety Administration (NHTSA), a division of the United States 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 (voiced by Jack Burns) and Larry (voiced by Lorenzo Music) who modeled seat belt safety practices through their slapstick antics, with the slogan "You Could Learn a Lot from a Dummy". Since then crash dummy characters have continued to be used 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 NHTSA television advertisements. They were intended to fall apart at the touch of a button on their abdomens. Vehicles which could be crashed into walls and broken were also produced. Dummies and vehicles were easily reassembled. They 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 and a video game for the Super Nintendo Entertainment System and Game Boy were produced.
- In 2004 a series of "Crash Dummies" animated shorts were commissioned for the FOX network. Related toys from Mattel's Hot Wheels brand were produced.
- The television series MythBusters employs a crash test dummy, "Buster", for dangerous experiments.
- In Discovery Kids children's educational series Crash Test Danny the title character is a living crash test dummy, played by Ben Langley, who gets crushed, blown up, and pulled apart in the name of science.
See also
- Car accident
- Crash test
- Crashworthiness
- Euro NCAP
- Safety car
- Mannequin
- Crash simulation
- Secchi disk, the characteristic test-dummy fiducial marker symbol.
Footnotes
References
External links
- Research of the Relationship of Pedestrian Injury to Collision Speed, Car-type, Impact Location and Pedestrian Sizes using Human FE model (THUMS Version 4)
- Crash Test Dummy
Source of article : Wikipedia
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