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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
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
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), wa ...
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
LS-DYNA is an advanced general-purpose multiphysics simulation software package developed by the former Livermore Software Technology Corporation (LSTC), which was acquired by Ansys in 2019. While the package continues to contain more and more p ...
,
PAM-CRASH,
MSC Dytran,
MADYMO
MADYMO (MAthematical DYnamic MOdels) is a software package for the analysis of occupant safety systems in the automotive and transport industries.
The software was developed by the Netherlands Organization for Applied Scientific Research (TNO) an ...
) 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 the ...
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
The head injury criterion (HIC) is a measure of the likelihood of head injury arising from an impact. The HIC can be used to assess safety related to vehicles, personal protective gear, and sport equipment.
Normally the variable is derived from t ...
(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 Army, 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 India, Partition of British India, wh ...
began serious
accident analysis
Accident analysis is carried out in order to determine the cause or causes of an accident (that can result in single or multiple outcomes) so as to prevent further accidents of a similar kind. It is part of ''accident investigation or incident inv ...
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 helicopter, utility military helicopter manufactured by Sikorsky Aircraft. Sikorsky submitted the S-70 design for the United States Army's Utility Tactical Transpo ...
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 visi ...
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
An airbag is a vehicle occupant-restraint system using a bag designed to inflate extremely quickly, then quickly deflate during a collision. It consists of the airbag cushion, a flexible fabric bag, an inflation module, and an impact sensor. T ...
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 attributes ...
s.
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" rela ...
, 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 m ...
, 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 primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
. They have each developed their own authoritative safety requirements and conducted extensive research and development in the field.
See also
*Airbag
An airbag is a vehicle occupant-restraint system using a bag designed to inflate extremely quickly, then quickly deflate during a collision. It consists of the airbag cushion, a flexible fabric bag, an inflation module, and an impact sensor. Th ...
*Airworthiness
In aviation, airworthiness is the measure of an aircraft's suitability for safe flight. Initial airworthiness is demonstrated by a certificate of airworthiness issued by the civil aviation authority in the state in which the aircraft is register ...
* Anticlimber
A cowcatcher, also known as a pilot, is the device mounted at the front of a locomotive to deflect obstacles on the track that might otherwise damage or derail it or the train.
In the UK small metal bars called ''life-guards'', ''rail guard ...
*Automobile safety
Automotive safety is the study and practice of design, construction, equipment and regulation to minimize the occurrence and consequences of traffic collisions involving motor vehicles. Road traffic safety more broadly includes roadway design.
...
* Buff strength
Buff strength is a design term used in the certification of passenger railroad cars. It refers to the required resistance to deformation or permanent damage due to loads applied at the car's ends, either from push-or-pull loads on the buffer, Jan ...
of rail vehicles
*Bumper (car)
A bumper is a structure attached to or integrated with the front and rear ends of a motor vehicle, to absorb impact in a minor collision, ideally minimizing repair costs. Stiff metal bumpers appeared on automobiles as early as 1904 that had a ...
* Compressive strength
In mechanics, compressive strength or compression strength is the capacity of a material or structure to withstand loads tending to reduce size (as opposed to tensile strength which withstands loads tending to elongate). In other words, compre ...
* Container compression test
The container compression test measures the compressive strength of packages such as boxes, drums, and cans. It usually provides a plot of deformation vs compressive force.
It is commonly used to evaluate shipping containers made of corrugated ...
*Crash test
A crash test is a form of destructive testing usually performed in order to ensure safe design standards in crashworthiness and crash compatibility for various modes of transportation (see automobile safety) or related systems and comp ...
*Crash test dummy
A crash test dummy, or simply dummy, is a full-scale anthropomorphic test device (ATD) that simulates the dimensions, weight proportions and articulation of the human body during a traffic collision. Dummies are used by researchers, automobi ...
*Hugh DeHaven Hugh DeHaven (3 March 1895 – 13 February 1980) was an American pilot, engineer and passive safety pioneer. DeHaven survived a plane crash while training as a Royal Canadian Flying Corps pilot during the First World War, and became interested in ...
* Jerome F. Lederer
*
*Roadworthiness
Roadworthiness or streetworthiness is a property or ability of a car, bus, truck or any kind of automobile to be in a suitable operating condition or meeting acceptable standards for safe driving and transport of people, baggage or cargo in road ...
*Seakeeping
Seakeeping ability or seaworthiness is a measure of how well-suited a watercraft is to conditions when underway. A ship or boat which has good seakeeping ability is said to be very seaworthy and is able to operate effectively even in high sea stat ...
*Seat belt
A seat belt (also known as a safety belt, or spelled seatbelt) is a vehicle safety device designed to secure the driver or a passenger of a vehicle against harmful movement that may result during a collision or a sudden stop. A seat belt reduc ...
* Seaworthiness
Seakeeping ability or seaworthiness is a measure of how well-suited a watercraft is to conditions when underway. A ship or boat which has good seakeeping ability is said to be very seaworthy and is able to operate effectively even in high sea stat ...
*Self-sealing fuel tank
A self-sealing fuel tank is a type of fuel tank, typically used in aircraft fuel tanks or fuel bladders, that prevents them from leaking fuel and igniting after being damaged.
Typical self-sealing tanks have multiple layers of rubber and reinforc ...
*Spaceworthiness
Spaceworthiness, or aerospaceworthiness, is a property, or ability of a spacecraft to perform to its design objectives and navigate successfully through both the space environment and the atmosphere as a part of a journey to or from space.
As in ...
* Telescoping (rail cars)
In a railway accident, telescoping occurs when the underframe of one vehicle overrides that of another, and smashes through the second vehicle's body. The term is derived from the resulting appearance of the two vehicle bodies: the body of on ...
References
Further reading
*RDECOM TR 12-D-12
Full Spectrum Crashworthiness Criteria for Rotorcraft
Dec 2011.
*USAAVSCOM TR 89-D-22A, Aircraft Crash Survival Design Guide
Volume I - Design Criteria and Checklists
Dec 1989.
*USAAVSCOM TR 89-D-22B, Aircraft Crash Survival Design Guide
Volume II - Aircraft Design Crash Impact Conditions and Human Tolerance
Dec 1989.
*USAAVSCOM TR 89-D-22C, Aircraft Crash Survival Design Guide
Volume III - Aircraft Structural Crash Resistance
Dec 1989.
*USAAVSCOM TR 89-D-22D, Aircraft Crash Survival Design Guide
Volume IV - Aircraft Seats, Restraints, Litters, and Cockpit/Cabin Delethalization
Dec 1989.
*USAAVSCOM TR 89-D-22E, Aircraft Crash Survival Design Guide
Volume V - Aircraft Postcrash Survival
Dec 1989.
*{{citation, doi=10.1016/j.compstruct.2006.04.083, title=A new composite energy absorbing system for aircraft and helicopter, journal=Composite Structures, volume=75, issue=1–4, pages=14–23, year=2006, last1=Taher, first1=S.T, last2=Mahdi, first2=E, last3=Mokhtar, first3=A.S, last4=Magid, first4=D.L, last5=Ahmadun, first5=F.R, last6=Arora, first6=Prithvi Raj
External links
Army Helicopter Crashworthiness
at DTIC
Basic Principle of Helicopter Crashworthiness
at US Army Aeromedical Laboratory
National Crash Analysis Center
History of Energy Absorption Systems for Crashworthy Helicopter Seats
at FAA
MIT Impact and Crashworthiness Lab
Transport safety
Aviation accidents and incidents