The structural behavior of automobile seats and seatbacks is one of the factors often examined in investigating injuries to a vehicle's occupant(s) in crashes. In the product liability arena, this topic is one of special interest in rear crashes. What role do these structures play in these cases? This is a brief report based on our structural and statistical analyses as well as the relevant published research.
The Debate: The product liability debate has focused on 'stiff' seatbacks versus 'yielding' seatbacks and the advantages of each in reducing rear crash injuries.
Terminology: It should be noted that seatbacks are 'distributed structures' and thus cannot be scientifically described by a single parameter or by one simple term ('stiff', 'yielding' etc). These non-technical, quantitative descriptions of distributed structures are used to convey the notion that one seatback ('stiff') would have undergone smaller deformations in a controlled laboratory test with specific loads as compared to another ('yielding') seatback in exactly the same test.
Do Seatbacks Fail?: All structures deform (i.e. yield under loading). Seatback deformations may consist of several components:
Future: Improving safety in high speed rear crashes ranks probably as a low priority in traffic safety for the US government because of the relatively few major injuries and fatalities associated with this crash mode.
Comparison of this 'exposure' data with the 'recorded injury' data in the NASS-CDS database (1996-2007) shows that rear impacts are associated with comparatively lower rates of injuries than do other crash modes. The number of occupants with recorded maximum abbreviated injury severity ('AIS') greater than or equal to 2 (level 2 indicates 'moderate' level of injury on the 'AIS' scale) is shown here.
Dr. Mukul Verma is a well-known expert in Automobile Safety and Crashworthiness, Vehicle Structures, Product Design, and Statistical Analyses of Traffic Trends and Regulations . He has worked in many engineering and management positions at a major automobile manufacturer including assignments in R&D, vehicle design, analysis and testing and engineering program management.
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