DOCSLIB.ORG

The Role of Seatback and Head Restraint Design Parameters on Rear Impact Occupant Dynamics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Role of Seatback and Head Restraint Design Parameters on Rear Impact Occupant Dynamics THE ROLE OF SEATBACK AND HEAD RESTRAINT DESIGN PARAMETERS ON REAR IMPACT OCCUPANT DYNAMICS Michael Kleinberger Most researchers agree that whiplash injuries are Liming Voo related to the relative motion between the head and Andrew Merkle torso, and that the reduction of this relative motion Matthew Bevan will lead to a decrease in the incidence of these Shin-Sung Chang injuries. Further, it has been shown that the relative Johns Hopkins Univ. Applied Physics Laboratory motion between the head and neck is greatly affected United States of America by seat design, and in particular by the position of the head restraint relative to the head [6-7]. Head Felicia McKoy restraint height and backset (horizontal distance Computer Systems Management, Inc. between the head and head restraint) are the two seat United States of America design parameters most commonly used to evaluate Paper Number 229 the response of an occupant to a rear impact collision. ABSTRACT Svensson et al [2] investigated the relationship between head restraint position and the occurrence of Although typically classified as AIS 1, whiplash injuries to the cervical nerve roots. They have injuries continue to represent a substantial societal demonstrated through a series of porcine problem with associated costs estimated at over $5 experiments that the relative motion between the billion annually in the US. The primary objective of head and neck during a rear impact causes the lower this study was to determine the effects of seatback cervical spine to go into local extension while the and head restraint design parameters on occupant upper cervical spine goes into local flexion. This response in rear impact. difference in curvature causes pressure variation and fluid movement within the spinal canal, which is Rear impact sled tests were conducted using the believed to generate injurious stresses and strains to Hybrid III mid-sized male (50M) dummy seated in a the exposed tissues. modified production seat, which allowed for the adjustment of recliner stiffness, seatback cushion Other researchers have focused on the vertebral level stiffness, and head restraint height. Instrumentation effects of the relative motion between the head and provided measurements of neck forces and moments, torso. Kaneoka et al [3] and Ono et al [4] have head motion relative to the torso, seatback rotation, conducted rear impact tests using volunteers and and head contact. An on-board digital video camera cineradiography. They have shown that during a rear recorded dummy kinematics. Results from this study impact, relative motion between adjacent vertebrae indicate that the risk of whiplash injury is not simply may cause impingement of the lateral facets and related to head restraint position, but is dependent on pinching of the surrounding soft tissues. Yoganandan a combination of factors related to both head et al [5] have also demonstrated this pinching restraint and seatback design. mechanism using a cadaveric head-neck experimental model on a mini-sled system driven by an impact pendulum. INTRODUCTION Siegmund et al [6] conducted a series of volunteer Although typically classified as AIS 1, whiplash tests on 42 subjects, including 21 males and 21 injuries continue to represent a substantial societal females. They performed a multiple linear regression problem with associated costs in the US estimated by analysis to determine the relative influence of various the National Highway Traffic Safety Administration factors related to the subject and vehicle. Their (NHTSA) at $5.2 billion annually [1]. Despite years results showed that vehicle speed change and relative of research by numerous investigators, the specific head restraint position explained the largest mechanisms of whiplash injuries continue to be a proportion of the observed variation in peak source of debate within the automotive safety occupant kinematic response. community [2-7]. Kleinberger 1 Kleinberger et al [7] evaluated the effect of head were initially created to predict serious AIS 3+ restraint position on occupant response using a injuries and are only useful in a qualitative manner computational model. Their results showed that the for predicting minor whiplash injuries. The tension- forces and moments acting at the top of the neck, and extension criterion is represented by the formula also the acceleration and rotation of the head relative to the torso decreased as the head restraint was F M = Z + Y moved higher and closer to the back of the NTE (2) occupant's head. Fint M int Seatback properties, such as cushion stiffness and where FZ and MY are the axial force and extension energy absorption, have also been identified as moment calculated at the occipital condyles, potential factors affecting occupant response to rear respectively. Fint and Mint are the normalizing critical impact. Welcher and Szabo [8] evaluated the values for the force and moment, respectively. The performance of five seats with varying properties currently accepted critical values for the 50M Hybrid using volunteer subjects. Head restraint position was III dummy in tension-extension are Fint=6806N and found to be most influential on occupant head-neck Mint=135Nm [11] for AIS 3+ injuries. kinematics. Head restraint height and backset were found to be significantly correlated with rearward Schmitt et al [12] proposed a modified version of the translational motion of the head relative to the torso. Nij criteria, called the Nkm Criteria, which combines Backset was found to be significantly correlated with the effects of shear force and flexion-extension the relative extension of the head, while head moment in the upper cervical spine. Using "e" for restraint height was significantly correlated with the extension, "f" for flexion, "a" for anterior shear, and head acceleration relative to the torso during the "p" for posterior shear, the four individual criteria are flexion phase of the impact. Nea,Nep,Nfa, and Nfp. The criteria is represented by the formula Several different criteria have been proposed by researchers in an attempt to predict the occurrence of F M = x + Y whiplash injuries. Since there is currently no N km (3) consensus on any of these criteria, this paper will Fint M int include calculations for several of the more commonly used criteria. Bostrom et al [9] proposed where FX and MY are the shear force and extension the Neck Injury Criterion (NIC), which is based on moment measured at the upper neck load cell, the Navier Stokes equations and the assumption that respectively. Fint and Mint are the normalizing critical fluid flow within the spinal canal causes pressure values for the shear force and moment, respectively. gradients that are injurious to the nerve roots. The The critical values are MY = 47.5 Nm in extension, criteria is represented by the formula MY = 88.1 Nm in flexion, and FX = 845 N in both anterior and posterior shear. These criteria were 2 developed to assess the risk of low severity whiplash NIC = 0.2a + v rel (1) rel injuries using the Hybrid III dummy with a TRID neck. The authors state that these values may need to where arel and vrel are the acceleration and velocity of be revised for use with other dummies. the occipital condyles relative to the T1 vertebra, respectively. Prasad et al [13] conducted a series of rear impact sled tests with different seat designs to determine the Kleinberger et al [10] proposed the Nij neck injury relationships between seat design parameters and the criteria, which combines the effects of forces and forces and moments measured at the upper and lower moments acting at the occipital condyles. This neck load cells. Results indicated that the extension criteria actually consists of four separate criteria for moment measured at the lower neck load cell was predicting injuries related to the four primary modes most sensitive to seat design and crash severity. of cervical loading, namely compression-flexion (NCF), compression-extension (NCE), tension-flexion Finally, the head rotation relative to the upper torso (NTF), and tension-extension (NTE). For rear impact is also presented as a potential injury criteria related testing, the NTE criterion is generally the most to rear impact whiplash injuries. This is based on the critical. It is important to note that the Nij criteria premise that cervical injuries are related to the Kleinberger 2 relative motion between the head and torso, and that Tests were conducted on a Via Systems deceleration controlling this relative motion should reduce the sled using the Hybrid III mid-sized male (50M) incidence of whiplash injuries. Ideally, both the dummy seated in a rear-facing seat. A sinusoidal sled relative translations and rotations should be pulse with a nominal impact speed of 17 kph was measured. However, it is difficult to measure the used that fit within the FMVSS 202 dynamic testing relative translation without requiring video analysis, corridor. The peak acceleration and duration of the which is impractical for certain types of testing. pulse was 9.0 g's and 90 msec, respectively, as shown in Figure 2. Viano et al [14] conducted a series of rear impact tests with the BioRID and Hybrid III dummies using several different production seats. Measured dummy responses were compared with insurance claims data. The authors proposed a Neck Displacement Criterion (NDC), which is based on the relative displacement and rotation between the occipital condyles and the T1 vertebrae as compared with the natural range of motion. This criterion was proposed as a supplement to other existing criteria until the mechanisms of whiplash injury are better understood. This paper evaluates the effects of seatback and head restraint properties on the occupant response to a rear impact collision. The injury criteria described above are used as a means of comparing the occupant responses under the various test configurations. For the seatback cushion stiffness evaluation, only relative head rotation is presented since the load cell data was not collected for this Figure 1.
Load more

Recommended publications
  • A Proposal for Rear Seat Head Restraint Geometric Ratings
    A PROPOSAL FOR REAR SEAT HEAD RESTRAINT GEOMETRIC RATINGS Avery, Matthew Weekes, Alix Mary Brookes, David Thatcham, UK Paper Number 11-0131 ABSTRACT The paper offers a new insight into the protection offered by rear seat head restraints against whiplash Consumer safety ratings organisations have injuries. The ratings can be used by consumer published static ratings of the head restraint safety organisations to increase public awareness geometry, with the aim of raising public awareness and to encourage development of rear seats that can of correct head restraint positioning, and offer protection against whiplash injuries. encouraging vehicle manufacturers to improve geometry. The geometry of front seat head INTRODUCTION restraints has improved each year, but the rear seats have not been investigated. Research into A number of consumer safety ratings organisations protection against whiplash injuries has shown that have published static ratings of the head restraint reducing the head restraint backset and improving geometry since 2003, with the aim of raising public height is effective in reducing real world injury awareness of correct head restraint positioning, and risk. In comparison to the front seats whiplash encouraging vehicle manufacturers to improve injuries occur less frequently in the rear seats, but geometry. These geometric ratings assess the rear seat occupancy can be as high as 12%. The proximity of head restraint to the head of a 50th research objective in this paper is therefore to percentile male occupant, using a H-Point Machine examine the head restraint geometry of the rear (HPM) and Head Restraint Measuring Device seats in comparison to the front seats, by presenting (HRMD) [1].
    [Show full text]
  • US FMVSS 202 Impact.Pdf
    /ulNir/ A Z 004 - /48Qq- - I-- --m- e--- t3 People Saving People U.S. Department http://uww.nhtsa.dot.gov Of Transportation FINAL REGULATORY IMPACT ANALYSIS FMVSS NO. 202 HEAD RESTRAINTS FOR PASSENGER VEHICLES Office of Regulatory Analysis and Evaluation National Center for Statistics and Analysis November 2004 EXECUTIVE SUMMARY The Final Rule This Final Regulatory Impact Analysis accompanies a final rule to require front seat head restraints in passenger cars, pickups, vans, and utility vehicles to be capable of achieving a height where the top of the head restraint is at least 800 mm (3 1.5 inches) above the H-point (which represents the normally seated 50thmale hip point). The final rule would also add a lower limit on height; head restraints in all front outboard seats may not be less than 750 mm (29.5 inches) from the H-point. The final rule would not require rear outboard head restraints, but would specify that if head restraints are installed they must be at least 750 mm. It also would require in front seats only that the distance between the back of the head form representing the position of a 50thpercentile head, in a normally seated position, and the head restraint (defined as backset) be no farther than 55 mm (2.2 inches) in any adjustment position. Benefits The benefits of increasing the height of head restraints and limiting the backset of head restraints are estimated to be: 15,272 whiplash injuries reduced in the front seat 1,559 whiplash injuries reduced in the rear seat 16,83 1 total whiplash injuries reduced costs ($2002) Average costs per vehicle are estimated to be: $4.51 in front seats $1.13 in rear seats for vehicles with rear head restraints $5.42 per average vehicle Total cost per year is estimated to be $84.2 million ($70.1 million for the front seat and $14.1 million for the rear seat).
    [Show full text]
  • Are Rear Headrests Required by Law
    Are Rear Headrests Required By Law How tendentious is Willem when unexcavated and unassociated Taber abridging some squeal? Mousier and half-bred Horacio never mime his persuader! Kin bewitch her spinster awa, she succusses it unthoughtfully. The examiner will check exist the normal unrestricted power anything and the restricted power table of your motorcycle at the tower of the test. Dh out of rear headrests are. In reducing whiplash? How can feedback improve overall site? Adjustable rear by changes are a headrest; rear facing you will not demonstrated that these vehicles? The Agency recent statistics on effectiveness of head restraints in passenger cars. Lower leg injuries can result from direct impact play the fascia, according to the petitioner. About Us Located on 26 acres in rural Perry Missouri Yancey Auto Parts has that large inventory to meet your needs You feel't find it better selection of recycled. Stars are fund of the published document. 315 Deck PointDeck Point is sea point wise the white rear-window glazing. No requirement tests that are headrests legal requirements of seats? If by law required by law sign up for headrest, are unrestrained or abbreviations identifying any laws? States issues of evaluation criteria set your child occupant physique and higher than on ads to reduce vehicle accidents happen to only when for testing active headrests law, unless otherwise indicated. Trailering with whiplash, especially overnight, as in unborn babies. Federal Motor Vehicle Safety Standard 202 has required head restraints in. To complete online edition to not reported to see over his shoulder belt should sit as he would be commented in.
    [Show full text]
  • A Thesis Entitled the Effect of Head Restraint
    A Thesis entitled The Effect of Head Restraint Material Properties, Initial Backset, and T1 Acceleration Magnitude on the Risk of Whiplash Injury: A Finite Element Study by Dhanvin Sunil Desai Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Bioengineering _________________________________________ Dr. Vijay K. Goel, Committee Chair _________________________________________ Dr. Anand K.Agarwal, Committee Member _________________________________________ Dr. Scott C. Molitor, Committee Member _________________________________________ Dr. Patricia R. Komuniechi, Dean College of Graduate Studies The University of Toledo August 2013 Copyright 2013, Dhanvin Sunil Desai This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of The Effect of Head Restraint Material Properties, Initial Backset, and T1 Acceleration Magnitude on the Risk of Whiplash Injury: A Finite Element Study by Dhanvin Sunil Desai Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Bioengineering The University of Toledo August 2013 Whiplash sprains and/or strains occur in 28-53% of motor vehicle collision victims, making it the most common type of injury in these collisions. The costs annually in the United States of whiplash injury are approximately between 4.5 to 8 billion dollars. Whiplash can have long-term symptoms which can lead to chronic pain. Theories have linked the risk of whiplash injury to facet joints, ligaments, intervertebral discs, vertebral arteries, dorsal root ganglia, and neck muscles. Head restraints were invented in the 1960s to reduce spinal motion by limiting relative motion between the head and thorax.
    [Show full text]
  • HCTP Report V0.6
    Vehicle improvements to reduce the number and severity of rear end crashes RWG Anderson, MRJ Baldock CASR REPORT SERIES CASR052 December 2008 Report documentation REPORT NO. DATE PAGES ISBN ISSN CASR052 December 2008 56 978 1 920947 64 4 1449-2237 TITLE Vehicle improvements to reduce the number and severity of rear end crashes AUTHORS RWG Anderson, MRJ Baldock PERFORMING ORGANISATION Centre for Automotive Safety Research The University of Adelaide South Australia 5005 AUSTRALIA SPONSORED BY Heads of Compulsory Third Party Insurance In Australia and New Zealand Motor Accident Commission GPO Box 1045 South Australia 5005 AUSTRALIA AVAILABLE FROM Centre for Automotive Safety Research http://casr.adelaide.edu.au/ /publications/researchreports/ ABSTRACT This report reviews vehicle technology developed to reduce the incidence of rear end crashes and the whiplash injuries that may result. Chapters cover: crash avoidance measures, passive safety measures built into improved seat and head restraint designs, assessment procedures that have been developed to assess the efficacy of various seat and head restraint designs in rear impacts, testing and assessment programs that are used to inform consumers of the relative performance of the seats in different models of vehicle and includes up-to-date information on the recently released EuroNCAP proposal to assess whiplash protection measures, the uptake of both seat-based whiplash countermeasures and also brake assistive technologies in Australia, and research on the costs and benefits of vehicle based measures to reduce rear end crashes and whiplash injury. Commentary is given on the opportunities for increasing the awareness of consumers in relation to vehicle based rear-end crash and whiplash countermeasures.
    [Show full text]
  • IIHS Head Restraint Ratings | 2001 Passenger Cars
    How the Institute necessary to protect an average-size rates head restraints male from whiplash injury. Accept- able and good restraints are high Head restraint good, acceptable, enough to protect taller occupants marginal, or poor as well as people of average height Restraint geometry is and shorter. Good and acceptable basis for most ratings; head restraints also have smaller good ratings awarded to backsets, which benefit occupants of active head restraint designs all heights. 2001 PASSENGER CARS Head restraint evaluations are The rating for a fixed head re- Acura CL/TL/RL based on two criteria. The first is the straint is straightforward. The zone Acura Integra distance down from the top of the into which its height and backset Audi A4/S4 head of an average-size male to the place it also defines its rating. Audi A6 top of the restraint. A head restraint Rating adjustable head restraints Audi A8 should be at least as high as the that don’t lock in their adjusted posi- Audi Allroad Quattro 1 Audi TT Roadster Quattro head’s center of gravity, or about 3 ⁄2 tions is equally straightforward — inches below the top of the head. the rating is defined by the zone for BMW 3 series BMW 5 series The second criterion is backset, height and backset in the down and/or rear position. For adjustable BMW 7 series the distance from the back of an BMW M3 restraints that lock in position when average-size male’s head to the front BMW Z3 Roadster of the restraint. Backsets of more adjusted, the rating is based on the Buick Century than about 4 inches have been asso- midpoint of the best (highest and Buick LeSabre ciated with increased symptoms of closest) and worst (lowest and far- Buick Park Avenue neck injury in crashes.
    [Show full text]
  • An Evaluation of Head Restraints Usdepor,Ment Federal Motor Vehicle Safety of Transportation R>J
    February 1982 DOT HS-806-108 NHTSA Technical Report An Evaluation of Head Restraints usDepor,ment Federal Motor Vehicle Safety of Transportation r>j. *j *j r\r\r\ Nj3p» standard 202 Administration Plans and Programs Office of Program Evaluation This document is available to the U.S. public through the National Technical Information Service, Springfield, Virginia 22161 Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catolog No. DOT HS-806 108 A. Title and Subtitle 5. Report Dote AN EVALUATION OF HEAD RESTRAINTS February 1982 Federal Motor Vehicle Safety Standard 202 6. Performing Organization Code NPP-10 8. Performing Orgonizatjon Report No. 7. Author's) Charles Jesse Kahane, Ph.D. 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Office of Program Evaluation National Highway Traffic Safety Administration 11. Contract or Grant No. 400 Seventh Street, S.W. 13. Type of Report and Period Covered 12. WashingtonSponsoring Agenc, y D.CNam.e and2059 Addres0s U.S. Department of Transportation NHTSA Technical Report National Highway Traffic Safety Administration 14. Sponsoring Agency Code Washington, D.C. 20590 15. Supplementary Notes An Agency staff review of an existing Federal regulation performed in response to Executive Order 12291. 16. Abstract Head restraints were installed in passenger cars largely in response to Federal Motor Vehicle Safety Standard 202. The purpose of a head restraint is to prevent whiplash injury of the neck in rear impact crashes. The objectives of this Agency staff evaluation are to determine how many injuries integral and adjustable head restraints have eliminated in highway accidents, to measure the actual cost of the restraints, to assess cost effectiveness and to describe the operational performance and problems of integral and adjustable restraints.
    [Show full text]
  • DEPARTMENT of TRANSPORTATION National
    This document is scheduled to be published in the Federal Register on 12/28/2016 and available online at https://federalregister.gov/d/2016-31405, and on FDsys.gov DEPARTMENT OF TRANSPORTATION National Highway Traffic Safety Administration [Docket No. NHTSA-2016-0116; Notice 1] Ford Motor Company, Receipt of Petition for Decision of Inconsequential Noncompliance AGENCY: National Highway Traffic Safety Administration (NHTSA), Department of Transportation (DOT). ACTION: Receipt of petition. SUMMARY: Ford Motor Company (Ford), has determined that certain model year (MY) 2015-2017 Ford F-150 and Ford F-Super Duty pickup trucks do not fully comply with Federal Motor Vehicle Safety Standard (FMVSS) No. 202a, Head Restraints. Ford filed a noncompliance information report dated October 18, 2016. Ford also petitioned NHTSA on November 17, 2016, for a decision that the subject noncompliance is inconsequential as it relates to motor vehicle safety. DATES: The closing date for comments on the petition is [INSERT DATE 30 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER]. ADDRESSES: Interested persons are invited to submit written data, views, and arguments on this petition. Comments must refer to the docket and notice number cited in the title of this notice and submitted by any of the following methods: 2 Mail: Send comments by mail addressed to U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE, Washington, DC 20590. Hand Delivery: Deliver comments by hand to U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE, Washington, DC 20590.
    [Show full text]
  • Toyota Motor Engineering & Manufacturing North America, Inc
    This document is scheduled to be published in the Federal Register on 03/14/2018 and available online at https://federalregister.gov/d/2018-05136, and on FDsys.gov DEPARTMENT OF TRANSPORTATION National Highway Traffic Safety Administration [Docket No. NHTSA-2016-0129; Notice 2] Toyota Motor Engineering & Manufacturing North America, Inc., Grant of Petition for Decision of Inconsequential Noncompliance AGENCY: National Highway Traffic Safety Administration (NHTSA), Department of Transportation (DOT). ACTION: Grant of petition. SUMMARY: Toyota Motor Engineering & Manufacturing North America, Inc., on behalf of Toyota Motor Corporation and certain other specified Toyota manufacturing entities (collectively referred to as “Toyota”), has determined that certain model year (MY) 2016-2017 Lexus RX350 and Lexus RX450H motor vehicles do not fully comply with Federal Motor Vehicle Safety Standard (FMVSS) No. 202a, Head Restraints. Toyota filed a noncompliance information report dated November 29, 2016. Toyota also petitioned NHTSA on December 21, 2016, for a decision that the subject noncompliance is inconsequential as it relates to motor vehicle safety. FOR FURTHER INFORMATION CONTACT: Ed Chan, Office of Vehicle Safety Compliance, NHTSA, telephone (202) 493-0335, facsimile (202) 366-3081. SUPPLEMENTARY INFORMATION: 2 I. Overview: Toyota, has determined that certain MY 2016-2017 Lexus RX350 and RX450H motor vehicles do not fully comply with paragraph S4.5 of FMVSS No. 202a, Head Restraints (49 CFR 571.202a). Toyota filed a noncompliance information report dated November 29, 2016, pursuant to 49 CFR part 573, Defect and Noncompliance Responsibility and Reports. Toyota also petitioned NHTSA on December 21, 2016, pursuant to 49 U.S.C. 30118(d) and 30120(h) and 49 CFR part 556, for an exemption from the notification and remedy requirements of 49 U.S.C.
    [Show full text]
  • Avery 1 a PROPOSAL for REAR SEAT HEAD RESTRAINT
    A PROPOSAL FOR REAR SEAT HEAD RESTRAINT GEOMETRIC RATINGS Avery, Matthew Weekes, Alix Mary Brookes, David Thatcham, UK Paper Number 11-0131 ABSTRACT The paper offers a new insight into the protection offered by rear seat head restraints against whiplash Consumer safety ratings organisations have injuries. The ratings can be used by consumer published static ratings of the head restraint safety organisations to increase public awareness geometry, with the aim of raising public awareness and to encourage development of rear seats that can of correct head restraint positioning, and offer protection against whiplash injuries. encouraging vehicle manufacturers to improve geometry. The geometry of front seat head INTRODUCTION restraints has improved each year, but the rear seats have not been investigated. Research into A number of consumer safety ratings organisations protection against whiplash injuries has shown that have published static ratings of the head restraint reducing the head restraint backset and improving geometry since 2003, with the aim of raising public height is effective in reducing real world injury awareness of correct head restraint positioning, and risk. In comparison to the front seats whiplash encouraging vehicle manufacturers to improve injuries occur less frequently in the rear seats, but geometry. These geometric ratings assess the rear seat occupancy can be as high as 12%. The proximity of head restraint to the head of a 50th research objective in this paper is therefore to percentile male occupant, using a H-Point Machine examine the head restraint geometry of the rear (HPM) and Head Restraint Measuring Device seats in comparison to the front seats, by presenting (HRMD) [1].
    [Show full text]
  • Occupant Responses to Active Head Restraints
    PERFORMANCE OF SEATS WITH ACTIVE HEAD RESTRAINTS IN REAR IMPACTS Liming Voo Bethany McGee Andrew Merkle Michael Kleinberger Johns Hopkins University Applied Physics Laboratory United States of America Shashi Kuppa National Highway Traffic Safety Administration United States of America Paper Number 07-0041 ABSTRACT Administration (NHTSA) estimates that the annual cost of these whiplash injuries is approximately $8.0 Seats with active head restraints may perform better billion (NHTSA, 2004). Numerous scientific studies dynamically than their static geometric characteristics reported connection between the neck injury risk and would indicate. Farmer et al. found that active head seat design parameters during a rear impact (Olsson restraints which moved higher and closer to the 1990, Svensson 1993, Eichberger 1996, Tencer 2002 occupant’s head during rear-end collisions reduced and Kleinberger 2003). When sufficient height was injury claim rates by 14-26 percent. The National achieved, the head restraint backset had the largest Highway Traffic Safety Administration (NHTSA) influence on the neck injury risk. In addition to its recently upgraded their FMVSS No. 202 standard on static position relative to the occupant head, the head restraints in December 2004 to help reduce structural rigidity of the head restraint and its whiplash injury risk in rear impact collisions. This attachment to the seat back can have a significant upgraded standard provides an optional dynamic test impact on the neck injury risk in a rear impact (Voo to encourage continued development of innovative 2004). Farmer et al. (2003) and IIHS (2005) technologies to mitigate whiplash injuries, including examined automobile insurance claims and personal those that incorporate dynamic occupant-seat injury protection claims for passenger cars struck in interactions.
    [Show full text]