- Crashworthiness
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Crashworthiness is the ability of a structure to protect its occupants during an impact. This is commonly tested when investigating the safety of aircraft and vehicles. Depending on the nature of the impact and the vehicle involved, different criteria are used to determine the crashworthiness of the structure. Crashworthiness may be assessed either prospectively, using computer models (e.g., LS-DYNA, MSC-Dytran, MADYMO) or experiments, or retrospectively by analyzing crash outcomes. Several criteria are used to assess crashworthiness prospectively, including the deformation patterns of the vehicle structure, the acceleration experienced by the vehicle during an impact, and the probability of injury predicted by human body models. Injury probability is defined using criteria, which are mechanical parameters (e.g., force, acceleration, or deformation) that correlate with injury risk. A common injury criterion is the Head impact criterion (HIC). Crashworthiness is assessed retrospectively by analyzing injury risk in real-world crashes, often using regression or other statistical techniques to control for the myriad of confounders that are present in crashes.
Contents
History
Aviation
The history of aviation crashworthiness can likely trace its beginning in the studies by John Stapp to investigate the limits of human tolerance in the 1940s and 1950s. In the 1950s and 1960s, the US Army beginning serious accident analysis into crashworthiness as a result of fixed-wing and rotary-wing accidents. As the Army's doctrine changed, helicopters became the primary mode of transportation in Vietnam. Pilots were receiving spinal injuries in otherwise survivable crashes due to decelerative forces on the spine and fires. Work began to develop energy absorbing seats to reduce the chance of spinal injuries.[1] during training and combat in Vietnam. Heavy research was conducted into human tolerance, energy attenuation and structural designs that would protect the occupants of military helicopters.[2][3] The primary reason is that ejection or exiting a helicopter is impractical given the rotor system and typical altitude at which Army helicopters fly. In the late 1960s the Army published the Aircraft Crash Survival Design Guide.[4] The guide was revised several times and became a muli-volume set divided by aircraft systems. The intent of this guide is to assist engineers in understanding the design considerations important to crash-resistant military aircraft. Consequently, the Army establish a military standard (MIL-STD-1290A) for light fixed and rotary-wing aircraft.[5] The standard establishes minimum requrements for crash safety for human occupants based on the need to maintain a livable volume or space and the reduction of decelerative loads upon the occupant.[6]
Crashworthiness was greatly improved in the 1970s with the fielding of the Sikorsky UH-60 Black Hawk and the Boeing AH-64 Apache helicopters. Primary crash injuries were reduced, but secondary injuries within the cockpit continued to occur. This led to the consideration of additional protective devices such as airbags. Airbags were considered a viable solution to reducing the incidents of head strikes in the cockpit, and were incorporated in Army helicopters.
Current stakeholders
The Federal Aviation Administration has been the proponent for general aviation safety in the United States. It has developed its own authoritative safety requirements in the Code of Federal Regulations.[7]
At the time NASA has conducted similar work study the effects of space launch for human space flight. They also conducted crash testing beginningin the 1950s.[8]
The US Department of Transportation has developed standards for private and commercial forms of transportation.
See also
- Airbag
- Automobile safety
- Bumper (automobile)
- Crash test dummy
- Hugh DeHaven
- Self-sealing fuel tanks
References
- ^ The Evolution of Energy Absorption Systems for Crashworthy Helicopter Seats by Stan Desjardins, paper at 59th AHS Forum
- ^ Human Tolerance and Crash Survival - Shanahan (NATO)
- ^ History of Full-Scale Aircraft and Rotorcraft Crash Testing
- ^ Aircraft Crash Survival Design Guide Volume 1
- ^ Military Standard for Light Fixed and Rotary-Wing Aircraft
- ^ Aircraft Crashworthiness Research Program - FAA
- ^ Code of Federal Regulations
- ^ History - Aircraft Crash Testing at NASA
External links
- Army Helicopter Crashworthiness at DTIC
- Basic Principle of Helicopter Crashworthiness at US Army Aeromedical Laboratory
- National Crash Analysis Center
- NHTSA Crashworthiness Rulemaking Activities
- History of Energy Absorption Systems for Crashworthy Helicopter Seats at FAA
- MIT Impact and Crashworthiness Lab
- School Bus Crashworthiness Research
- Rail Equipment Crashworthiness
- A new composite energy absorbing system for aircraft and helicopter
Categories:- Transport safety
- Aviation accidents and incidents by aircraft
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