Crashworthiness is the ability of a structure to protect its occupants during an impact. This is commonly tested when investigating the safety of

aircraft An aircraft is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or by using the Lift (force), dynamic lift of an airfoil, or in ...

and

vehicle A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), ...

s. 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, PAM-CRASH, 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 In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by ...

experienced by the vehicle during an impact, and the probability of injury predicted by human body models. Injury probability is defined using

criteria Criterion, or its plural form criteria, may refer to: General * Criterion, Oregon, a historic unincorporated community in the United States * Criterion Place, a proposed skyscraper in West Yorkshire, England * Criterion Restaurant, in London, En ...

, 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.

History

Aviation

The history of human tolerance to deceleration can likely trace its beginning in the studies by

John Stapp Colonel John Paul Stapp (July 11, 1910 – November 13, 1999), M.D., Ph.D., was an American career U.S. Air Force officer, flight surgeon, physician, biophysicist, and pioneer in studying the effects of acceleration forces on humans. He was a ...

to investigate the limits of human tolerance in the 1940s and 1950s. In the 1950s and 1960s, the

Pakistan Army The Pakistan Army (, ) is the land service branch of the Pakistan Armed Forces. The roots of its modern existence trace back to the British Indian Army that ceased to exist following the Partition of British India, which occurred as a result ...

began serious accident analysis into crashworthiness as a result of fixed-wing and rotary-wing accidents. As the

US Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

'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 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. 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. The guide was revised several times and became a multi-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 established a military standard (MIL-STD-1290A) for light fixed and rotary-wing aircraft. The standard establishes minimum requirements 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.Aircraft Crashworthiness Research Program
- FAA Crashworthiness was greatly improved in the 1970s with the fielding of the

Sikorsky UH-60 Black Hawk The Sikorsky UH-60 Black Hawk is a four-blade, twin-engine, medium-lift utility military helicopter manufactured by Sikorsky Aircraft. Sikorsky submitted the S-70 design for the United States Army's Utility Tactical Transport Aircraft System ( ...

and the

Boeing AH-64 Apache The Boeing AH-64 Apache () is an American twin- turboshaft attack helicopter with a tailwheel-type landing gear arrangement and a tandem cockpit for a crew of two. It features a nose-mounted sensor suite for target acquisition and night v ...

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

helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attribu ...

Regulatory agencies

The

National Highway Traffic Safety Administration The National Highway Traffic Safety Administration (NHTSA ) is an agency of the U.S. federal government, part of the Department of Transportation. It describes its mission as "Save lives, prevent injuries, reduce vehicle-related crashes" relat ...

, the

Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic ...

, the

National Aeronautic and Space Administration The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

, and the

Department of Defense Department of Defence or Department of Defense may refer to: Current departments of defence * Department of Defence (Australia) * Department of National Defence (Canada) * Department of Defence (Ireland) * Department of National Defense (Philipp ...

have been the leading proponents for crash safety in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

. They have each developed their own authoritative safety requirements and conducted extensive research and development in the field.

References

External links

Army Helicopter Crashworthiness
at DTIC
Basic Principle of Helicopter Crashworthiness
at US Army Aeromedical Laboratory
National Crash Analysis CenterHistory of Energy Absorption Systems for Crashworthy Helicopter Seats
at FAA
MIT Impact and Crashworthiness Lab
Transport safety Aviation accidents and incidents

History

Aviation

Regulatory agencies

See also

References

Further reading

External links