Crashworthiness
Encyclopedia
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 vehicle
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
, 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.
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. 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 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. 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.
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 helicopter
s.
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.
At the time NASA
has conducted similar work study the effects of space launch
for human space flight. They also conducted crash testing beginning in the 1950s.
The US Department of Transportation has developed standards for private and commercial forms of transportation.
Air safety
Air safety is a term encompassing the theory, investigation and categorization of flight failures, and the prevention of such failures through regulation, education and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel.-United...
and vehicle
Vehicle
A vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured, such as bicycles, cars, motorcycles, trains, ships, boats, and aircraft....
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
LS-DYNA is an advanced general-purpose multiphysics simulation software package developed by the Livermore Software Technology Corporation...
, MSC-Dytran
MSC Software
-History:MSC.Software Corporation was formed in 1963 under the name MacNeal-Schwendler Corporation . The company developed its first structural analysis software called SADSAM at that time, and was deeply involved in the early efforts of the aerospace industry to improve early finite element...
, MADYMO
MADYMO
MADYMO stands for MAthematical DYnamic MOdels. It is a software package developed by TASS , headquartered in Rijswijk, the Netherlands. It a leading design & analysis software for occupant safety systems in the transport industry....
) 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
G-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...
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.
Aviation
The history of aviation crashworthiness can likely trace its beginning in the studies by John StappJohn Stapp
John Paul Stapp, M.D., Ph.D., Colonel, USAF was a career U.S. Air Force officer, USAF flight surgeon and pioneer in studying the effects of acceleration and deceleration forces on humans...
to investigate the limits of human tolerance in the 1940s and 1950s. In the 1950s and 1960s, the US Army beginning serious accident analysis
Accident Analysis
Accident analysis is carried out in order to determine the cause or causes of an accident or series of accidents so as to prevent further incidents of a similar kind. It is also known as accident investigation. It may be performed by a range of experts, including forensic scientists, forensic...
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. 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 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. 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.
Crashworthiness was greatly improved in the 1970s with the fielding of the Sikorsky UH-60 Black Hawk
Sikorsky UH-60 Black Hawk
The UH-60 Black Hawk is a four-bladed, twin-engine, medium-lift utility helicopter manufactured by Sikorsky Aircraft. Sikorsky submitted the S-70 design for the United States Army's Utility Tactical Transport Aircraft System competition in 1972...
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
Head injury
Head injury refers to trauma of the head. This may or may not include injury to the brain. However, the terms traumatic brain injury and head injury are often used interchangeably in medical literature....
in the cockpit, and were incorporated in Army helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...
s.
Current stakeholders
The Federal Aviation AdministrationFederal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...
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.
At the time NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
has conducted similar work study the effects of space launch
Space launch
Space launch is the earliest part of a flight that reaches space. Space launch involves liftoff, when a rocket or other space launch vehicle leaves the ground at the start of a flight...
for human space flight. They also conducted crash testing beginning in the 1950s.
The US Department of Transportation has developed standards for private and commercial forms of transportation.
See also
- AirbagAirbagAn Airbag is a vehicle safety device. It is an occupant restraint consisting of a flexible envelope designed to inflate rapidly during an automobile collision, to prevent occupants from striking interior objects such as the steering wheel or a window...
- Automobile safetyAutomobile safetyAutomobile safety is the study and practice of vehicle design, construction, and equipment to minimize the occurrence and consequences of automobile accidents. Automobile safety is the study and practice of vehicle design, construction, and equipment to minimize the occurrence and consequences of...
- Bumper (automobile)
- Crash test dummyCrash test dummyCrash test dummies are full-scale anthropomorphic test devices that simulate the dimensions, weight proportions and articulation of the human body, and are usually instrumented to record data about the dynamic behavior of the ATD in simulated vehicle impacts...
- Hugh DeHaven
- Self-sealing fuel tanks
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