Seat Back Failures

Xprts safety experts demonstrated by 1999 that children in the rear seat of vehicles in which the front seat failed had a statistically significant higher risk of injury than if the front seat did not fail. The information provide the basis for several subsequent research papers and lawsuits that resulted in findings of defects in passenger vehicle seat design that are still tested with methods that are over 40 years old.

Related Papers and Presentations

Seat Failure in Rear Impacts, International Mechanical Engineering Congress & Exposition (IMECE)

ABSTRACT

An analysis of rear end accident involving 1377 driver and right front seat occupants was conducted examining the probability of seat performance failure as a function of crash severity and the injury severity as a function of both crash severity and seat performance.  The results suggest that occupants with seat failures experience serious injury more frequently than without such failures for the same Delta-V. Intrusion into the area behind the occupant's seat appears to be an important consideration in increasing the risk of injury.

Serious Injury in Rear Vehicular Impacts, Biomedical Engineering Society, Engineering in Medicine and Biology Society Conference

ABSTRACT

Various studies suggest that yielding vehicular seats reduce the potential for injury, in contrast others suggest serious trauma to front and rear seat occupants when front seats collapse rearwards. This study shows that front seat failures cause greater serious injury to front seat occupants with the same change in vehicle speed due to a rear impact.

Effects of Front Seat Performance Failure on Rear Seat Occupant Injuries in Rear Impacts, Advances in Bioengineering, ASME Conference

ABSTRACT

An analysis of rear end accidents involving rear seat occupants seated behind a front seat occupant was conducted examining the probability of serious injury as a function of both crash severity and front seat performance failure. Seat performance failure is when some element of the seat fails to do what it is designed to do, e.g. a seat back lock allows the seat back to move during the collision. The results suggest that the risk of serious injury is greater in the 6.7-1 1.2 m/s Delta-V crash severity range when the seat in front of the occupant suffers a performance failure.

Study of Seat System Performance Related to Injury of Rear Seated Children & Infants in Rear Impacts, ASME International Mechanical Engineering Congress & Exposition

ABSTRACT

Since 1996 the NHTSA has warned of the airbag deployment injury risk to front seated children and infants, during frontal impact, and they have recommended that children be placed in the rear seating areas of motor vehicles. However, during most rear impacts the adult occupied front seats will collapse into the rear occupant area and, as such, pose another potentially serious injury risk to the rear seated children and infants who are located on rear seats that are not likely to collapse. Also, in the case of higher speed rear impacts, intrusion of the occupant compartment may cause the child to be shoved forward into the rearward collapsing front seat occupant thereby increasing impact forces to the trapped child. This study summarizes the results of more than a dozen actual accident cases involving over 2-dozen rear-seated children, where 7 children received fatal injuries, and the others received injuries ranging from severely disabling to minor injury. Types of injuries include, among others: crushed skulls and brain damage; ruptured hearts; broken and bruised legs; and death by post-crash fires when the children became entrapped behind collapsed front seat systems. Several rear-impact crash tests, utilizing sled-bucks and vehicle-to-vehicle tests, are used to examine the effects of front seat strength and various types of child restraint systems, such as booster seats and child restraint seats (both forward and rearward facing), in relation to injury potential of rear seated children and infants. The tests utilized sedan and minivan type vehicles that were subjected to speed changes ranging from about 20 to 50 kph (12 to 30 mph), with an average G level per speed change of about 9 to 15. The results indicate that children and infants seated behind a collapsing driver seat, even in low severity rear impacts of less than 25 kph, encounter a high risk of serious or fatal injury, whether or not rear intrusion takes place. Children  seated in other rear seat positions  away from significant front seat collapse,  such as behind the stronger "belt-integrated" types of front seats or rearward but in between occupied collapsing front seat positions,  are less likely to be as seriously injured.

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