For more information
Call 1-800-351-0222
Call 1-800-351-0222
AUTO AIRBAGS.
Term Paper ID:22406
Essay Subject:
Need for & future of side airbags, design & technology, function & process, problems, regulations.... More...
15 Pages / 3375 Words
18 sources, 49 Citations,
APA Format
$60.00
More Papers on This Topic
Paper Abstract:
Need for & future of side airbags, design & technology, function & process, problems, regulations.
Paper Introduction:
Side Impact Airbags
During the past century, automobile accidents have killed and injured several million people. In the United States, motor-vehicle accidents are the number one cause of death for persons between the ages of 1 and 35 years. Such statistics have made safety a primary consideration among car buyers. Moreover, they have also led to the development of various vehicular safety devices. Seat belts and shoulder harnesses protect vehicle occupants during the course of an accident. However, because a large proportion of drivers and passengers do not wear seat belts, automobile manufacturers have designed passive-restraint safety systems. These devices automatically protect vehicle occupants. One such passive-restraint system consists of the airbag. Upon impact, airbags inflate immediately to absorb
Text of the Paper:
The entire text of the paper is shown below. However, the text is somewhat scrambled. We want to give you as much information as we possibly can about our papers and essays, but we cannot give them away for free. In the text below you will find that while disordered, many of the phrases are essentially intact. From this text you will be able to get a solid sense of the writing style, the concepts addressed, and the sources used in the research paper.
(1994, April 11). Viano, D. In addition, light trucks and vanswill be bound by the requirements starting in the 1999 model year. WARD's AutoWorld, n.g., 9. (1993, July 19). Indeed, side impacts kill over 8, and seriously injureapproximately 24, Americans each year. 46). While sodium azide generants are most commonly employed in airbaginflator systems, hybrid inflators are also available. Computersimulation of occupant neck response to airbag deployment in frontalimpacts. 61-64). Additionally, most harmed occupantshave not been wearing seat belts. 18). "Transportation." (199 ). 9). Seat belts and shoulder harnesses protectvehicle occupants during the course of an accident. According to Mahon, "In a typical 3 -mile-per-hourcrash, an airbag system has from 6 to 2 milliseconds to decide fromacceleration or velocity-change sensor data whether a severe crash hasoccurred" (Ashley, 1994, pp. According to Geoffrey L. 11-13). 16i). Electromechanical sensors are typically installed in a multipoint ordistributed system. Moreover, there is directevidence that airbags do actually work. One of the first companies to producehybrid inflators was Allied-Signal. These airbags may hold as muchas 6 liters of gas. However, replacement systems forGeneral Motors vehicles run up to $1, ; Volvo replacement airbags cost$2, ("Just Who's", 1991, p. Automotive News, 69, 1,22. These devicestypically contain a cantilever beam or plate which has been chemicallyetched from a single quartz or silicon substrate. Insurance companiesand police claim that airbag thefts have become a serious problem in urban,high-theft areas such as New York City, parts of New Jersey, Florida, andCalifornia. Ithas been suggested that future airbags might be constructed from polyester. The sequence of events associated with airbag function occurextremely rapidly. Toprevent this lye formation, sodium azide suppliers mix in chemicals thatproduce sodium salts (e.g., silicates, aluminates, and borates) uponcombustion. Whenvehicles are scrapped, airbag canisters may be crushed. 58-61). Another disadvantage of airbags involves their influence on accidentoutcome. Different types of accelerometer may be used in airbag systems. Estimates of fatal chest and abdominal injuryprevention in side-impact crashes. Meister, J. Regardlessthough, the Office for the Study of Automotive Transportation at theUniversity of Michigan has conducted surveys demonstrating a steady trendamong automobile manufacturers favoring electronic sensors (Fleming, 1993,a., p. N.g.). Then, at45 to 5 milliseconds, the driver slams into the fully inflated bag.Eventually, about 85 to 1 milliseconds after impact, the driver "'ridesthe bag down,' unharmed, as the air cushion deflates" (Ashley, 1994, pp. Fleming, A. Scrapyard dangers from airbags. A second mechanical sensor employs the Hall effect to detectdeceleration. "Side-impact air bag development." (1994, May). So far, only Volvo has incorporated side airbags into its automobiledesigns. Security on the flanks. The sensor is "basicallya tiny mass (seismic mass) suspended from a spring in a frame" (Ashley,1994, pp. Automotive News,n.g., 24. A typical driver-side airbag consists of two circular pieces offabric which have been stitched together. I. Gates, M. Such statistics have made safety a primary consideration among carbuyers. K., & King, A. The ball is restrainedby both air damping, as well as a lever counterbalanced by a bias spring.During impact, the ball's movement rotates a D-shaped shaft that restrainsa firing pin. Vehicle deceleration sensors thenactivate crash-discrimination electronics to initiate airbag deployment.At roughly 18 to 23 milliseconds, this system fires a pyrotechnic squib andignites the sodium azide. Infact, there is presently some debate over the benefits of mechanicalsensors as compared to electronic sensors. R. Moreover,this energy is delivered a mere six inches from the driver's shoulder.Such force has the power to bend steel, shatter glass, and causeconsiderable injury (Lynch, 1994, pp. I. Moreover, 37 percent of the fatalities resulted from severe injuryto the chest and abdomen of these near-seated occupants. Henry, J. These operations may pay pettycriminals to supply them with airbags from specific car models ("Auto",N.g., p. 1 i). 4 ). Mahon, vicepresident for technology at airbag supplier, Breed Automotive, in BoontonTownship, N.J., "The airbag must never deploy when it is not needed", and"it must also be absolutely ready to go for at least 15 years" (Ashley,1994, pp. Of course, despite their various disadvantages, airbags do greatlyenhance automotive safety. The canister contains between 5 and 15 grams ofsodium azide (NaN3). This is achieved by pelletizing the sodiumazide. By tearing along scored linesduring inflation, the cover does not impede the airbag's escape. The repulsive force between the magnets' two likepoles subsequently causes them to move to the opposite ends of the tube.When an impact occurs, one of the magnets moves towards the tube's center.This movement may then be converted into an analog signal and used todetonate an airbag (Meister & Womble, 1993, pp. References Ashley, S. According to a 1991 State Farm report, it costs less than $5 to replace a Ford or Chrysler airbag. Without the restraint, riders moveforward and slap the bag early in its deployment. Researchers have found that protecteddrivers may still suffer serious internal injuries. Morespecifically, the standards focus on "force/acceleration limitations in thehead, chest, and femurs of a 5 th-percentile dummy during specific vehiclebarrier tests" (Frantom, 1989, pp. Such systems, however, do little to protect riders from side-impact accidents. 154).Consequently, motor vehicle safety has become a priority for car buyers,automobile manufacturers, and government authorities. (1994, October 1 ). However, because alarge proportion of drivers and passengers do not wear seat belts,automobile manufacturers have designed passive-restraint safety systems.These devices automatically protect vehicle occupants. A 3 -mile-per-hour collision into acar door delivers approximately 1 , foot-pounds of energy. Hence,only about 7 percent of automobile accident fatalities may be preventedthrough the use of additional safety devices. Side airbag systems are also being developed in Germany through ajoint effort involving Robert Bosch GmbH and Morton International ("Side-impact", 1994, p. Yang, K. Moreover, they have also led to the development of variousvehicular safety devices. Such injuries typically occurwhile the bags are still inflating. Such devastating effects mightbe prevented by side-impact airbags. It has beensuggested that side-impact airbags might guard against such injuries.Furthermore, even if side-impact airbags were only 2 percent as effectiveas frontal airbags, they might still prevent a significant number offatalities every year. Beard, J. Eachairbag also contains a gas generator and inflator device. Automotive News, n.g., 154. The gas was heated using an Arcite solid pyrotechnic. 58-61). Whenexposed to a specified threshold deceleration or velocity change, themechanism closes an electrical circuit and initiates bag inflation. Electrical current can be used to trigger a nitro-cellulose (i.e., gunpowder) explosive and detonate the sodium azide(Keebler & Gates, 1995, p. Despite such adversity though, there is currently a "scramble goingon to develop active technologies to protect occupants from sidecollisions" (Lynch, 1994, pp. 11-13). In addition, smart airbags could alsovary their response depending on whether or not a vehicle's occupants werewearing their seat belts. Although neoprene coatings may helpseal and protect an airbag, uncoated nylon is lighter and packs better. (1992, August). This problem,however, may be avoided through vehicle design modifications. 58-61). 9). While side-impact crashes may only involve a quarter ofthe energy of two cars hitting head-on, the relatively thin skin of theauto body--as compared to the bumper--may result in more severeconsequences. C. Automotive News, n.g., 46. 61-64). One such passive-restraint system consists of the airbag. 61-64). Design News, 45, 116-118. FMVSS 214 defines side-impact requirements for passengercars starting with the 1997 model year. According to the United States' National Safety Council, 3 millionAmericans have been killed and more than 2 million have been injured inautomobile accidents. Different UnitedStates companies which produce the micromachined accelerometers include I.C. However, according to Volvospokesperson, Jean Hill, this "first generation" system will provide thebackground necessary for the creation of more versatile side airbags. 43). 4 ). Regardless of the type of sensors employed by an airbag system, allmust be calibrated. This Fiberfrax mat acts as a filterand "ties up most of the remaining free sodium in the generated gas"(Ashley, 1994, pp. Release of the firing pin ultimately ignites a percussioncap detonator. This essentiallyconsists of a steel or aluminum canister about 6 centimeters long and 2centimeters across. These devices use asmall charge to heat pressurized argon gas. H.; Latouf, B. Buckling down on passengersafety. Automotive News, n.g., 18. Research conducted in 197 found that 6 percent of car occupants donot use lap belts. (1995, March 2 ). Design News,n.g., 165-167. du Pont de Nemours & Company in Wilmington, Delaware. Upon impact, airbags inflateimmediately to absorb riders' energy. Automotive safety is in the bag.Mechanical Engineering, n.g., 58-64. While theadverse effects of side airbags on infants and toddlers remain to bedetermined, such risks could be reduced through the use of either a cutoffswitch or sophisticated occupant sensing devices. The resulting deflection causesproportional variation of the capacitances between the plate and electrodesburied in the plate. The first United States automobile manufacturer to make airbagsstandard equipment was Chrysler Corporation. Keebler, J., & Gates, M. While Volvo asserts that the system will protect vehicleoccupants in 9 percent of serious-to-fatal side-impact collisions, thedevice may not deploy in all crash scenarios. The system involves two permanent magnets placed in astainless steel tube. This heated gas then hassufficient volume for bag inflation. "Auto thieves bypass radios for airbags." (N.g.). With these systems, the ball or mass is restrained by a magnetor a spring, and moves in proportion to the vehicle's deceleration. These may include two verticalpanels of fabric with a main horizontal panel between them. Compared to frontal impactcollisions, the response time for side airbags is considerably reduced.According to Philippe Lemaitre, vice president and general manager of theTRW Transportation Electronics division in Farmington Hills, Michigan,"Whereas a multipoint air bag system has about 2 milliseconds to respond,and a single-point system needs about 1 milliseconds, a side-impact baghas maybe 4 milliseconds" (Ashley, 1994, pp. Volvo accomplished their "lightning response"to vehicular collision by making various "tradeoffs" (Lynch, 1994, pp. 165-167). They then incorporated amechanical sensor into the outboard-forward corner of the Volvo's seat.The lower portion of the door deforms controllably, thus striking the seatedge and sensor. While the sensors do represent the lowcost alternative, however, there remain questions as to their effectivenessand reliability (Meister & Womble, 1993, pp. In addition, inflator units may also contain a layer of mattedalumina and silica known as Fiberfrax. Should the sodiumazide then leak into the environment, it may mix with water to form thetoxic volatile, hydrazoic acid (Beard, 1993, p. Second only to frontal impacts, side-impact collisionscause 2 percent of driver fatalities. 116-118). Airbags also have the potential to harm the environment. About 9 percent of 1994 modelyear cars contain at least a driver-side airbag. Automotive Engineering, 1 1, 11-13. Britannica, 28, 782-783. David Dahle, vice-president for design engineering at Morton Automotive Safety Products inOgden, Utah, recommends deploying airbags prior to sending cars to ashredder. Such sensors might onlydeploy in the presence of a seated passenger. More recently, ajoint venture between Allied-Signal and Atlantic Research--i.e., Bendix-Atlantic Inflator Company--has been established in Knoxville, Tennessee tofurther develop hybrid inflator technologies (Ashley, 1994, pp.61-64). For example, they focused on the most life-threatening scenario(i.e., an impact centered on the front door). 58-61). This prevents accidental detonation from the shocks andjolts associated with, for example, a deep pothole or a mechanic's hammer.Electromechanical sensors may consist of either the ball-in-tube or spring-mass types. Finally, airbags may also be subject to theft. 58-61). Automobile-industryanalysts predict that the total number of airbag systems installed in motorvehicles will exceed 4 million by the year 1996. Its modules are currently capable of deploying a side airbagcushion within 1 -12 milliseconds. This ensures that all serious crashes are detected.These systems are wired either in series or parallel combinations, and mayinclude a safing or arming sensor. This figure amounts to aworldwide market totalling over $6.6 billion (Ashley, 1994, pp. Crate, J. These might be avoided through the development of "smart" airbags(Henry, 1994, p. In certain cases,airbags have even injured vehicle occupants. AutomotiveEngineering, n.g., 4 . They then deploy forward from theoutboard side of the front seats. Micromachined silicon accelerometers are perhaps the least expensivesensor technology. Twenty-one to 27 milliseconds subsequent toimpact, pressurized nitrogen gas surges into the airbag itself. 145-151). In general, 9 to 1 mile-per-hour collisions will nottrigger most airbags; whereas, 14 to 16 mile-per-hour collisions will(Ashley, 1994, pp. It should also be noted that passenger-side airbags might possiblyharm children seated in rear-facing seats (Gates, 1994, p. However, while polyester is lighter, its performance over the typicalairbag lifespan of 15 years remains uncertain. While suchdesigns protect sensors from the hostile environment under the hood, theygenerally have "access to less information about the impact by the time adeployment decision must be made" (Ashley, 1994, pp. Breed Automotive has developed an all-mechanical spring-mass sensorwhich is suitable for single-point operation. Various problems which must be addressed relateto such issues as crash sensing, airbag deployment rate, and inflationforce management. "NHTSA sees injuries despite airbags." (1993, November 29).Automotive News, n.g., 16i. 18). With single-point systems, the accelerometeris packaged with the airbag unit in the passenger compartment. Upondetonation, their sodium azide is converted to harmless nitrogen gas.Unfortunately though, the majority of airbags are never used. The safing sensor is usually set to a 1- or 2-g preload. 11-13). The final part of the airbag system consists of its cover. Thismaterial is strong, abrasion-resistant, and long-lasting. Applications for airbags grow.Automotive News Insight, n.g., 1 i. Moreover, the same study found that shoulder-belt usagewas less than 3 percent. Two major nylonfiber suppliers in the United States include the Allied-Signal Corporationand E. Such accidentstypically involve high-speed impacts with fixed objects or heavy trucks.Of those accidents, however, where occupant death may be prevented, the useof seat belts results in a 43 percent reduction in fatality risk. For example, current airbagseither deploy completely or do not deploy at all. Whereas conventionaltriggering systems inflate the airbag after an impact has already pushedits way into a vehicle's door, future "proximity" sensors might employradar or infrared technology to inflate airbags prior to impact ("Side-impact", 1994, p. In the United States, motor-vehicle accidents arethe number one cause of death for persons between the ages of 1 and 35years. B., & Womble, M. Viano (1989) remarks on 1986 data involving side-impact, multiple-vehicle crashes which resulted in 5,458 fatalities (Viano, 1989, pp. 58-61). This allows the vehicle's occupant to gradually ride theairbag down without "bottoming against the wheel" (Frantom, 1989, pp. In addition to nitrogen, sodium azide also produces sodium. This generally involves adjusting a given airbag'svelocity thresholds according to specific vehicle's crash pulsecharacteristics. A dangerous device: With thecar came carnage--and the war's not over yet. Despite future technological innovations, however, all airbagtechnologies possess certain disadvantages. AutomotiveEngineering, n.g., 43. By applying a signal to the buried electrodes, thevariation in the capacitances can then be used to generate an analogvoltage which is characteristic of the applied forces. 58-61). This data emphasized the need for motor vehiclepassive restraints. Crash detectors, oraccelerometers, generally employ a crash-discrimination algorithm toevaluate any specific impact. Sensors in Milpitas, California, Lucas NovaSensor in Fremont,California, Analog Devices in Norwood, Massachusetts, and Motorola Inc. Next generation airbags will besmarter. The coverprotects the airbag prior to deployment. 58-61). 58-61). E. Unfortunately though, the design of side-impact airbags has presentedsafety engineers with numerous challenges. Thus, airbags are increasingly beinginstalled as a supplemental restraint system to be used in conjunction withbelts (Yang, Latouf, & King, 1992, p. Moreover, when thesedevices do deploy, they do so with considerable force. The results of a National Highway Traffic Safety Administrationresearch study indicate that airbags may alter various injury patternsassociated with certain collisions. Side Impact Airbags During the past century, automobile accidents have killed and injuredseveral million people. Lynch, T. The injuries typicallysustained consist of abrasions, cuts, bruises, and burns (Ashley, 1994, pp.58-61). Mechanical systems arecharacterized by their simplicity and relatively low cost. Because of the minimal crush zonebetween a vehicle's door and its occupants, side-impact airbags of thefuture may require new sensing technologies. A third approach to single point sensing involves micromachinedaccelerometers (Meister & Womble, 1993, pp. The development of side airbags presents engineers with numeroustechnological challenges. 782-783).As driver-side and passenger-side airbags proved effective through the198 s and into the 199 s, automobile manufacturers began to consider side-impact air bags. The investigatorsfound 24 percent fewer fatalities than would have been expected in frontand front-angle (i.e., 1 to 2 o'clock) collisions associated with airbag-equipped vehicles (Ashley, 1994, pp. Door mounted airbags are often placed either in the armrest or upperbody area ("Side-impact protection", 1994, p. By analyzing the effectiveness ofairbags in frontal crashes, researchers have been able to estimate thenumber of fatalities which might be prevented by side-impact air bags.Approximately 5 percent of all fatal crashes involve forces so severe thatoccupant death cannot be prevented by design modification. Journal of Biomechanical Engineering, 114, 327-331.----------------------- 1 (1993, May 22). 11-13). The bagsthemselves may be coated or uncoated. This amounted to approximately 87 deployments for every 1, collision claims ("Just Who's", 1991, p. Whenmanufactured in bulk, the sensors cost between $15 and $18 each (Ashley,1994, pp. Airbags are packed into their inflator modules like parachutes.Folding pattern can significantly affect inflation speed and may helppreclude a phenomenon known as "bag slap" (Ashley, 1994, pp. This canbe manufactured from polyurethane or some other plastic. (1993, April). Automakers want on-off switch forairbags. The automotive airbag system is actually quite "a remarkableengineering achievement" (Ashley, 1994, pp. Theairbags are triggered mechanically. (1993, September 27). Already, various governments have mandated side-impact protections.For example, U.S. While such airbags are still in thedevelopmental stage, they should become widely available by the year 2 . The system consists of aball which moves forward down a close-fitting tube. They come as standard equipment in Volvo's 1995 85 Turbo. One recent study conducted by theInsurance Institute for Highway Safety in Arlington, Va., examined 18, driver crash deaths during the period from 1985 to 1992. inPhoenix, Arizona (Ashley, 1994, pp.61-64). FMVSS 2 8 emphasizesautomatic force/acceleration limitation for motor vehicle occupants. "In addition,"Lemaitre notes, "side collisions offer a much wider set of impactpossibilities in terms of angles and places to hit" (Ashley, 1994, pp. During the early 197 s, the companyused cylinders of argon pressurized at 25 to 35 pounds per square inch. Any acceleration along the plate's input axis causes itto rotate about its flexure point. Vent holes in the bag fabric control its leak rate subsequentto inflation. In addition, a diagnostic circuit monitorssystem readiness and provides backup power during electrical failure. In order to reduce costs, automotive manufacturers have also designedsingle-point sensor systems. With the widespread application of side airbags,their potential for preventing injury should increase substantially. (1994, January). In the early 199 s, it wasalso Chrysler Corporation vehicles that had the most airbag deployments.Between July 199 and June 1991, Chrysler vehicles sustained 1,284 airbagdeployments. Whenfree sodium mixes with water, it forms sodium hydroxide, or lye. 1). As airbags become standard equipment in cars and light trucks, theairbag market should expand considerably. Eventually, airbags should become more convenient, lessexpensive, and safer. "Side-impact protection alternatives." (1994, May). Frantom, R. Side-impactairbags may be installed in trim, behind trim, or housed in a separate doorunit. 165-167). Through pressure variations,electromagnetic sensing, or infrared means, they might, for example,identify a child seat and halt airbag deployment (Ashley, 1994, pp.61-64).The sensors could also tailor airbag deployment to the number of occupantsin a given vehicle (Henry, 1994, p. Air bag impactsensing. According to the United States'Federal Motor Vehicle Safety Standard (FMVSS) 2 8, all passenger cars andlight trucks must eventually have airbags for both outboard front-seatoccupants. In contrast, passenger-side units are roughly 3 to 5times larger and more teardrop-shaped. This signal maythen be amplified and analyzed (Meister & Womble, 1993, pp. 43). "Just who's using these air bags anyway?" (1991). (1994, April 18). (1989, October 2). NewScientist, n.g., n.g. In conjunction with the automobile's"beefed-up" passenger cage, the airbags provide Volvo passengers withconsiderable side-impact protection (Lynch, 165-167). Pelletization controls both the chemical's surface area and itsrate of gas generation. L. InEurope, similar regulations go into effect for 1996 model year vehicles("Side-impact protection", 1994, p. The photolithographic and chemical etching processesused to manufacturer the devises are similar to those used to manufacturemicroelectronic components in bulk. 11-13). 327). 61-64).Maximum deployment speeds in 199 cars range from about 9 to 2 miles perhour. At present, most airbags are consist of nylon 6 or nylon 6.6. (1989). Since airbag inflators must liberate large quantities of nitrogen gasin as few as 2 to 4 milliseconds, the devices are designed to meet acertain mass-flow outputs. However, theseinjuries may no longer be externally visible ("NHTSA", 1993, p. It wasfound that the near-side seated occupants accounted for 64 percent of thedeaths. The impact points ranged 2 to 4 o'clock and 8 to 1 o'clock. At present, automatic seatbelts and airbag restraints comprise the only two systems capable ofcomplying with the standard. Few automotive systemsare subject to more extreme performance and reliability requirements(Meister & Womble, 1993, pp. N.g.). Finally, whereas the crush zone for frontal impacts is measured inmeters, that for side impacts may be limited to several centimeters.Hence, not only is the reaction time for side-impact collisions severelyshortened, but the amount of crush that can be absorbed by body structureis significantly reduced. Finally, most airbag systems also include some type of moduleenclosure and mounting hardware (Ashley, 1994, pp. Such devises would deploy with full force only whenit is absolutely necessary; during less severe collisions, the smartairbags might deploy more gently. 165-167). This coalition, United Airbag Systems (UNAS) GmbH,has considered locating side airbags in vehicle seats, headliners, anddoors. In fact, over the last 3 decades, more Americansdied in traffic accidents than were killed in all of the nation's wars,ranging from "the Revolution to the Gulf" (Crate, 1993, p. Vehiclestructures may be engineered to reliably transmit crash pulses directly tothe airbag sensor. Within milliseconds the generant will beconverted into harmless nitrogen gas which then fills the airbag (Beard,1993, n.g.). 61-64). Airbag theft may result fromunscrupulous body shops and salvage yards. 116-118). 58-61). Such devices protect the occupant of a vehicle withoutrequiring any action on their part ("Transportation", 199 , pp. Journal of Safety Research, 2 , 145-152.
If this paper is not what you are looking for, you can search again:
or
We can write a Custom Essay just for you.
Browse Essays by Subject