| Seat properties affecting neck responses in rear crashes: a reason why whiplash has increased. | |
| | |
MedLine Citation:
|
PMID: 14522646 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
Whiplash has increased over the past two decades. This study compares occupant dynamics with three different seat types (two yielding and one stiff) in rear crashes. Responses up to head restraint contact are used to describe possible reasons for the increase in whiplash as seat stiffness increased in the 1980s and 1990s. Three exemplar seats were defined by seat stiffness (k) and frame rotation stiffness (j) under occupant load. The stiff seat had k=40 kN/m and j=1.8 degrees /kN representing a foreign benchmark. One yielding seat had k=20 kN/m and j=1.4 degrees /kN simulating a high-retention seat. The other had k=20 kN/m and j=3.4 degrees /kN simulating a typical yielding seat of the 1980s and 1990s. Constant vehicle acceleration for 100 ms gave delta-V of 6, 10, 16, 24, and 35 km/h. The one-dimensional model included a torso mass loading the seatback, head motion through a flexible neck, and head restraint drop and rearward displacement with seatback rotation. Neck displacement was greatest with the stiff seat due to higher loads on the torso. It peaked at 10 km/h rear delta-V and was lower in higher-severity crashes. It averaged 32% more than neck displacements with the 1980s yielding seat. The high-retention seat had 67% lower neck displacements than the stiff seat because of yielding into the seatback, earlier head restraint contact and less seatback rotation, which involved 16 mm drop in head restraint height due to seatback rotation in the 16 km/h rear delta-V. This was significantly lower than 47 mm with the foreign benchmark and 73 mm with the 1980s yielding seat. Early in the crash, neck responses are proportional to ky/mT, seat stiffness times vehicle displacement divided by torso mass, so neck responses increase with seat stiffness. The trend toward stiffer seats increased neck responses over the yielding seats of the 1980s and 1990s, which offers one explanation for the increase in whiplash over the past two decades. This is a result of not enough seat suspension compliance as stronger seat frames were introduced. As seat stiffness has increased, so have neck displacements and the Neck Injury Criterion (NIC). High-retention seats reduce neck biomechanical responses by allowing the occupant to displace into the seatback at relatively low torso loads until head restraint contact and then transferring crash energy. High-retention seats resolve the historic debate between stiff (rigid) and yielding seats by providing both a strong frame (low j) for occupant retention and yielding suspension (low k) to reduce whiplash. |
| | |
Authors:
|
David C Viano |
Related Documents
:
|
15210106 - Siah proteins, hif prolyl hydroxylases, and the physiological response to hypoxia. 16813046 - Some effects of stimulant medication on response allocation: a double-blind analysis. 11132996 - Coronary spastic angina induced by anticholinesterase medication for myasthenia gravis-... 21873716 - Evaluation of physician assistants in national health service scotland. 11828576 - It's time for your checkup. 1807596 - Software quality regulation under the safe medical devices act of 1990: hospitals are n... |
Publication Detail:
|
Type: Journal Article |
Journal Detail:
|
Title: Traffic injury prevention Volume: 4 ISSN: 1538-9588 ISO Abbreviation: Traffic Inj Prev Publication Date: 2003 Sep |
Date Detail:
|
Created Date: 2003-10-02 Completed Date: 2004-03-25 Revised Date: 2004-11-17 |
Medline Journal Info:
|
Nlm Unique ID: 101144385 Medline TA: Traffic Inj Prev Country: United States |
Other Details:
|
Languages: eng Pagination: 214-27 Citation Subset: IM |
Affiliation:
|
ProBiomechanics LLC, Bloomfield Hills, Michigan 48304-2952, USA. dviano@comcast.net |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Accidents, Traffic* Biomechanics Equipment Design Head / physiology* Head Protective Devices* Humans Manikins Motion Neck / physiology* Risk Factors Whiplash Injuries / epidemiology, etiology*, physiopathology* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Prediction of cervical spine injury risk for the 6-year-old child in frontal crashes.
Next Document: Seat influences on female neck responses in rear crashes: a reason why women have higher whiplash ra...