Heredity: Crash Course Biology # 9
Photo Chris Mueller half of a mannequin The vinyl flesh was removed from half of this model to expose his skeleton and sensors Its manufacturer, DAE Denton, normally attributed that serial numbers to his models, but this special unit , used in trade shows around the world, has been dubbed Fred.
His bare buttocks rest on the cold plate steel; skin smooth, hairless has a horrible orange-pink hue Toeless His feet are nearby, next to his head, chest, arms, Is it the hands and legs macabre scene of some ritualistic slaying.
Not quite a technician in a white coat enters the room and carries the body parts at a wooden workbench It takes an Allen wrench and screw the feet to the legs, hands arms, then the legs and head to the torso When it is finished, another hybrid midsize III dummy adult male began to come to life, or at least what passes for life in a crash-test dummy.
This hybrid III is the work of Denton ATD, a company of 170 employees with facilities in Michigan and Ohio that manufactures some of the crash test dummies today's most advanced These human surrogates simulate how the body of a real person answer in a car accident and help to ensure that a new car seat belts, air bags, head and armrests, structural framework, interior padding and other elements provide good protection.
In a few days, this new hybrid III unit will be instrumented with force, torque and acceleration sensors, then shipped to automakers not disclosed in the Detroit area Here, it will be placed in brand new cars and endure a tortuous line injury and insult frontal collisions, rollovers, rear and side crashes to certify that all vehicles of the automaker can protect their human occupants in case of accident.
The test dummy, that is, could one day save your life, but you will probably never encounter this electromechanical marvel He doesn t even have a name in the registers that record the dummy components, its crash-test history and, ultimately, when he retired, he'll simply be known as No. 0200-137.
Last summer, I visited Denton to see how the company makes its extraordinary models Denton assembly plant is set among cornfields just outside the quaint town of Milan, the population of the Ohio 1445 birthplace of Thomas Edison.
When I ENTER everywhere unpretentious building, the first things I see are the body parts of the business by his rib cage, said Mike Beebe, senior vice president at Denton and a leading expert on art world and science of making models It the box of the spine, with all the different parts s abdomen are the legs chiefs arm, I try to organize mentally a complete body out parts messy, but what comes to mind is something alarmingly Picasso-esque.
Beebe points to a photo showing a group of mannequins Family Portrait, launches Does The family includes the most widely used model, the Hybrid III 50th percentile male, supposed to represent the average North American man he weighs 78 kilograms and is 1 to 75 meters high and reach that height he could stand, he can t, because he's sitting Standing Hybrid III mode has a small woman Hybrid III 5th percentile female, three children Hybrid III old 10 years, 6 years old, who tipped the scales at 100 kg on the big guy and 3 years, and an oversized cousin Hybrid III male 95th as Beebe said.
This dummy family is designed to be used in crash tests that simulate frontal impacts squarely cars operating in other cars, trees, walls that sort of thing also in Denton catalog of 40 models are models for side effects testing, rear impacts, pedestrian accidents, and air bag blows on small children Denton clients include Chrysler, Ford, Honda, Hyundai, Nissan, Porsche, Volkswagen, Tata Motors India, and China FAW the company ships from 20 to 25 models per month.
Beebe says that in a crash test, the sensors of a model record a range of parameters of the force of a blow to the thigh, the torque on the neck during a sudden deceleration, compression of the chest against a seatbelt These measurements are then converted to injury criteria that reveal anything harm a minor concussion to death would have been done for if they had been aware as human injuries to vehicle occupants is mainly researchers who study how Newtonian mechanics applies to the human body, usually by making the impact and deceleration tests on corpses of pig carcasses, or eager graduate students.
But Denton models do more than car accidents tests They've been used in roller coasters in Iowa and simulated train derailments in India they have been dropped from a plane, strapped into the helicopter crash, and shot cannons They have checked school bus seats, air bags motorcycle and ski slope protection nets an Australian clothing company commissioned a perfect size 10 model to try its new styles and in a program of TV, a hybrid face Denton III was struck by a professional boxer and place in a neck lock by a Brazilian jujitsu fighter.
There were some applications where we had no idea what they were doing, said Beebe owned or government-related Dummies brand new left, they came back in some areas.
A dummy as No. 0200-137 consists of 350 metal and plastic parts Denton manufactures most of them himself, and almost everything is done by hand.
the first skin, the flexible plastic salmon color that covers the body of a model to make the feet, for example, a worker pays a liquid vinyl milkshake-like substance in an aluminum mold of size a brick inside the mold is shaped like a foot which is a toeless foot model and vinyl solidify or cure, when it goes into an oven skin to the manikin head, arms, forearms, hands , thighs and shins is the fact in the same way.
In another part of the plant, a group of workers transformed steel and aluminum parts for the skeleton of the dummy A technician loads specifications in a computer numerically controlled, or CNC, machines which automatically cut, drills and mills a steel part in this case, a complex drive for the shoulder of the dummy Over in another corner, a worker leans long strips of steel that will form No. 0200-137 s Co-workers call coasts such Rib Man.
As workers weld the smaller pieces to the larger, pieces of the skeleton starting to take the shape of the skull, spine, hips, ankles, knees, elbows The neck model is more complex Much car accidents, collisions particularly at the rear, the result in severe neck injuries to create a structure that can mimic the movement of a human neck, a worker mixed together natural rubber, polyacrylates, nitrile, neoprene and butyl to obtain specific damping characteristics It injects the mixture into a press mold that a handful of disc-shaped pieces, to be alternated with metallic rings to form the hybrid III neck segmented feature.
Different sectors of the plant No. 0200-137 of the vinyl or metal parts converge in the assembly area where they await that the white coating to the technician technician starts with measuring and weighing head, limbs and torso, and with a special scale, it determines the center of gravity of each section, which should match that of a real person to assemble the model, all you need is a bunch of hex head screws and a key but no 0200-137 is not yet ready, it needs some sensors.
The second day in Denton, I head headquartered in Rochester Hills, Michigan From remarks Beebe, I already have an idea that the company appreciates the humor in otherwise serious work, it's my suspicions are quickly confirmed bobbleheads dummy greet visitors at the reception; a poster of a model posing as Rodin's The Thinker is hanging in a hallway.
When I walk into the office area of Denton President and CEO, David Stein, I get more than I spend my day with mannequins is one of his favorite voltage circuit breakers Stein, an electrical engineer turned dummy Executive -industrie, shows me his collection of miniature crash test dummy toys and dolls purchased on eBay.
The purpose of my visit is to know how the company is pushing the envelope of the dummy design, and I anticipated that Stein wouldn t be forthcoming with details of the specifications of a model, I reasoned, probably as the formula for Coca-Cola or plans for the Boeing 787 secreted away in a vault under guard.
Not so Dummy specifications the United States are public, Stein said you can walk into the offices of the National Highway Traffic Safety Administration in Washington, D and C of the application 74-14 record; in it you will find diagrams, assembly descriptions, performance requirements, and a 16-page list of parts for the Hybrid III 50th percentile.
The reason for keeping open fictitious specifications so is that car manufacturers, security equipment suppliers, dummy makers, and NHTSA crash tests that most new car models before you can go on the US market, are all on the same page the European Union and other countries have similar regulations.
So, in principle, everyone can get the specifications and build a Hybrid III dummy The challenge, says Stein, is consistency meets the requirements while your next indistinguishable mannequin previous Shaping models that are like clones takes many expertise in fact, only two companies in the world have the expertise to build the most advanced models Denton and First Technology Safety Systems in Plymouth, Michigan.
Make public and official dummy specifications also has a downside, you can t improve a dummy model given after the government froze its design The Federal Motor Vehicle Safety Standard No. 208, passenger crash protection, which dictates how the models are to be built among others, was enacted in the US in 1972 and hasn t changed considerably since, so the dummy makers need to certain older models 30 and materials.
In fact, some manufacturing techniques back just after the Second World War, when the US military developed the first modern models for testing ejection seats in airplanes Colonel John Stapp, a US Air Force physician, pioneer in the field of biomechanics with research involving submit volunteers, including himself, to the deceleration defying court death on sleds he realized later it was more productive to develop and use of crash test dummies an annual meeting of the same name, the car crash Stapp Conference is always the rendezvous of car- crash testers, biomechanical researchers and other experts in the security industry.
In the 1960s and early 1970s, with traffic accidents killing over 50 000 people on US roads each year, the demand for safer vehicles was reinforced in 1971, General Motors, which had been developed some dummy prototypes, decided to combine two competing designs of elements, one of Alderson research Laboratories and the other Sierra GM engineering named the hybrid model resulting rightly hybrid I.
Meanwhile, various manufacturers have created a myriad of other models, some now long retired, others still serving Aerospace variety includes model T artificial Parachute, Torso, dynamic and Dan The medical profession has to Rando radiotherapy, Dexter dental Dummy, and cardiac chest Phantom Phantom family, nuclear Phantom and Phantom scanning organs.
The automotive sector has increased its own fictitious families now retired Sierra Family Sierra Sam Sierra Stan, Sierra Susie Sierra Saul small Sierra Sammy and Sierra infant and hybrid hybrid clan I, II and III latter variety created by GM to NHTSA, which is responsible for the design in the 1970s are the latest side impact units SID EuroSID, BioSID and WorldSID These models, such as hybrids, have specifications drawn up by agencies government, and Denton and other manufacturers follow such designs to manufacture and sell them to customers.
Today WorldSID is by far the most advanced model has been the first to be designed by a global consortium of industry, government and academic experts, in order to harmonize the testing protocols and safety standards, which may vary considerably from country to country Loaded with sensors, it can record 258 different measurements in a single crash test unit can operate almost 350 000 more than the price of a hybrid III twice.
Denton didn t start as a dummy The manufacturer originally focused on making society force and torque sensors, called load cells, which are used in crash test dummies, but also in many other parts equipment such as power tools and digital scales Robert A Denton founded the company in 1969. A calm and creative engineer, he produced his first load cells at his home near Troy, Michigan using the kitchen oven heal Denton components and engineers continued to design many of the most widely used charge of automobile cells today, including those used in the Hybrid III.
After its parts and mechanical skin were assembled, not 0200-137 is shipped from the factory in Denton Ohio to the company's load cell unit, next to its headquarters in Michigan.
In a large room, high-ceilinged, half a dozen humming away time milling machines to time, stop the machine and a worker retrieves the newly crushed part These parts, aluminum and steel, come in all shapes and sizes and form the structural elements of the load cells.
No. 0200-137 of the load cell of the femur, for example, is enclosed in an inner cylinder, a small metal beam traverses the length of cylinder If you compress the cylinder, the beam deforms To measure the extent of the deformation, the load cell uses a thin wire in zigzag fragile metal such as a titanium alloy, the electrical resistance of this yarn, or gauge, changes when you compress or stretch when the gauge is adhered to the beam, it converts the deformation of the beam in a variable voltage Add multiple beams and gauges, and your load cell can measure the force in additional directions, and because you know the dimensions of the beams, you can also measure the torque.
Metal parts are carried along in Denton laboratory electronics, where they will be equipped These gauges must be precisely bonded to the beam center or measures will be distorted Whereas the manufacture of the manikin has hitherto required a lot of lift heavy objects, hammering and milling, alignment and bonding tasks require finesse and eye-hand coordination Fourteen women are at work sitting in booths decorated with flowers and children's drawings, they intensely scrutinize microscopes and nimbly tiny pliers and wire cutter maneuver.
Like other hybrid models III, No. 0200-137 receive two other types of accelerometers sensors and potentiometers to measure the accelerations experienced by the dummy's head, for example, three uniaxial accelerometers are installed inside the skull at the center of gravity Potentiometers measuring deviation by translating their tensioning motion; supermodel receives one of these units behind the breastbone to measure the forces exerted by the seat belt or other object against the chest.
Now instrumented No. 0200-137 has one last stop before leaving the factory, it must be carefully checked in the laboratory certification Given what is happening here, you can just as easily call this place the dummy room of torture.
First comes the test head drop and the name pretty much says it all A technician stands No 0200-137 of the neck and head hangs from trees at a specific height of 37 6 cm above a heavy steel block a release mechanism drops magnetic head, which hit the block with a thud this test ensures that the head has the right weight and damping properties.
Then, the technician reconnects the head to the body and places the model on a platform, the positioning so that its chest conforms to a 23 kg steel cylinder probe impactor chest suspended above three, two a the probe swings down and connects the sternum mannequin, sending non-0200-137 flying backwards into a net impact deflects the potentiometer and technicians check that the data falls to a certain beach.
A few minutes later, the model is to get his neck bent in an ill-looking craft, and his knees whacked by another oscillating probe When it's all done, No. 0200-137 receives a certification stamp on its records and is ready to meet its future owner This means that packed in a cardboard box and delivered by truck.
The models of the future what will they look like to answer this question, we should visit the many organizations that in one way or another advance automakers dummy technology such as GM and Ford, NHTSA and counterparts in other countries, research groups in places such as Wayne State University, the University of Virginia and the University of Michigan, and the dummy manufacturers, of course.
But since I'm here in Denton, I ask Randy Kelly, vice president of sales for the company and a model spokesperson so Kelly was on TV a bunch of times to talk about models Model of future, he says, is already here in Rochester Hills There's two examples to show me.
One of the objectives of long biomechanical was to know exactly what is happening inside the chest during an accident, Kelly says that the interpretation particularly important in a side impact, where the armrest, a door or SUV fender can hit the passengers on the side, chattering ribs in the side impact current zero, potentiometers attached to each rib record the movement of the rib, but the device is monitoring deflections in one direction, so it's a little gross Denton engineers came up with a better way to capture all the action from the coast.
This is RibEye, Kelly said, pointing to the torso mannequin Nothing seems unusual, but he explains that instead of potentiometers, is equipped with an LED, and two angle light sensors are mounted on the spine each of the 12 ribs manikin the sensors track the position of each LED or a point on the coast, Kelly says is like celestial navigation that sailors were at the time.
The advantage of RibEye over existing methods is that it measures the movement in three dimensions with a precision of 1 millimeter Denton, which is associated with Boxboro Boxborough systems, mass to develop the system, he installed in several models customers are now testing RibEye in R & D programs.
The second Kelly draft mentions is FOCUS facial and ocular countermeasure for false security head, developed by Denton with the US Army Research Laboratory aeromedical and the Center for Biomechanics injuries, jointly managed by Virginia Tech College of Engineering, in Blacksburg, and Wake school Forest University drug, Winston-Salem, North Carolina FOCUS consists of an improved artificial face with synthetic eyeballs consist of a shaped penetration register silicon material injury and load cells on the back each eye socket to measure non-penetrating impacts face CUSTOM- also made load cells in several areas behind the frontal bone above the eye, the zygomatic bone on each side of the eyes, bone nasal, and the upper and lower jaws.
What's concentrate good for eye injuries to soldiers increased dramatically since World War II, Kelly explains, if the army plans to use to evaluate FOCUS helmets, goggles and protective characteristics the packed his vehicle sensor face can also be used to study the impacts of air-bag face, injuries related to motorcycle and sports injuries Oh and popping corks proved they represent about 10 percent of admissions to the eye hospital in Europe.
I do not meet a 0200-137 muggy afternoon in June at Autoliv in Auburn Hills, Michigan Autoliv, one of the largest suppliers of air bags in the world, seat belts and other automotive safety systems, also performs crash tests for customers that don t have their own crash test facilities such customer s No. 0200-137 owner makes a frontal crash test today the client allows me to observe the test as long as I leave out some details that might reveal the identity of the automaker and stay away from the vehicle in exchange, I can watch a brand new car get totaled 40,000 Sounds like a fair trade to me.
The test takes place in a controlled temperature and humidity to shed Eight other men and I'm sitting in a room viewing over the test track, a bit like a VIP box at a Formula One race unless this tough race about 10 seconds and the track is only 200 meters long.
The car, a greenish-gray four-door sedan, is the head of the track the bottom of the vehicle, technicians attach a cable to tow the center of the course at the opposite end is a 45-metric barrier of your concrete It armed S1 8 meters high, 1˝ 8 m thick, and 3 to 6 meters wide.
No 0200-137 is sitting in the driver's seat, his face expressionless save any last minute preparations going on around him, technicians carefully adjust the angle of his head, the space between his chest and the steering wheel, and tilting her thighs mannequin wearing a formfitting cotton short-sleeved shirt, shorts above the knee and a pair of size 11 black oxfords 125 It is to reproduce real driving conditions people usually lead with their clothes after all.
Suddenly, a buzzer sounds An orange LED indicator, huge light panels flood the test Fifteen cameras Bay high speed start rolling The noise of the tow rope slide down the track in 3 seconds sedan accelerates from 0 to 48 km h and for 7 seconds, it maintains the correct speed a moment before impact, the towing cable is released, and in the next moment, the car plant in Boom fragments barrier lights flying in all directions the rear wheels almost jump from the ground and then just silence.
The model measures will be transferred to computers, processed and translated into a report of injury criteria, which will tell how the automaker would have fared actual passenger in an accident, I'm not allowed to see No. 0200-137 after but chances are it is still in good shape, you may need a spare or two or realignment or perhaps some new clothes, but a little more than the next decade, it will be his routine Up the day when a new model takes its place.
To see more pictures of models along with a video of a chest impact test, visit.
For more technical details on Denton models, go.
Accidental Injury Biomechanics and Prevention, edited by Alan M Nahum and John W Melvin Springer-Verlag, 2001, several chapters on how the models are used in crash tests.
For a playful view of the field of biomechanics, see The Strange Life Stiff human history, for Cadavers Mary Roach W W Norton and Co., 2003.
Anatomy of a dummy CRASHTEST IEEE Spectrum, dummy, the most widely used.