The Evolution of Energy Absorption Systems for Crashworthy Helicopter Seats

Desjardins, Stanley P.

doi:10.4050/jahs.51.150

Cited by 42 publications

(38 citation statements)

References 4 publications

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“…Later on, the variable-profile energy absorber (VPEA) seat structure was developed to take advantage of the dynamic response of the occupant. The ultimate design is an automatic energy absorber (AEA), which provides the maximum amount of protection to a larger range of occupants [4]. It was determined in the early 1970s that the limit load or total dynamic stroking load [22,23] of an energy-absorbing system had to be set to a lower value (18 G) than originally thought.…”

Section: Introductionmentioning

confidence: 99%

“…Most of these seats use an energyabsorbing device that applies a constant load to decelerate the occupant and is referred to as a fixed-load energy absorber (FLEA). A manually adjustable or variable-load energy absorber (VLEA) was developed to produce the same level of protection for all sizes of occupants [4]. Later on, the variable-profile energy absorber (VPEA) seat structure was developed to take advantage of the dynamic response of the occupant.…”

Section: Introductionmentioning

confidence: 99%

“…A dynamic compression index (DCI) was defined and utilized by [16,17] as an inexpensive and time-conserving methodology for replacing seat cushions for aircraft seats. The DCI is the cushion compression distance available to the occupant before the [21], (b) cockpit seat with monolithic bucket [4]. cushion bottoms out during impact.…”

Section: Introductionmentioning

confidence: 99%

“…It was determined in the early 1970s that the limit load or total dynamic stroking load [22,23] of an energy-absorbing system had to be set to a lower value (18 G) than originally thought. This was based on the observation of seat performance relative to tolerance data assembled by Eiband [24], in order to account for dynamic overshoot and to keep the load-duration environment within the human tolerable range [4]. Following extensive tests, it was recommended that the load factor should be retained at 14.5 G for U.S. army aircraft seats, and between 11 G and 13 G for commercial and light aircraft, by using the energy-absorber system to protect the spine [21][22][23]25].…”

Section: Introductionmentioning

confidence: 99%

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Lumbar load attenuation for rotorcraft occupants using a design methodology for the seat impact energy-absorbing system

Moradi¹,

Beheshti

Lankarani

2012

Open Engineering

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Aircraft occupant crash-safety considerations require a minimum cushion thickness to limit the relative vertical motion of the seat-pelvis during high vertical impact loadings in crash landings or accidents. In military aircraft and helicopter seat design, due to the potential for high vertical accelerations in crash scenarios, the seat system must be provided with an energy absorber to attenuate the acceleration level sustained by the occupants. Because of the limited stroke available for the seat structure, the design of the energy absorber becomes a trade-off problem between minimizing the stroke and maximizing the energy absorption. The available stroke must be used to prevent bottoming out of the seat as well as to absorb maximum impact energy to protect the occupant. In this study, the energy-absorbing system in a rotorcraft seat design is investigated using a mathematical model of the occupant/seat system. Impact theories between interconnected bodies in multibody mechanical systems are utilized to study the impact between the seat pan and the occupant. Experimental responses of the seat system and the occupant are utilized to validate the results from this study for civil and military helicopters according to FAR 23 and 25 and MIL-S-58095 requirements. A model for the load limiter is proposed to minimize the lumbar load for the occupant by minimizing the relative velocity between the seat pan and the occupant's pelvis. The modified energy absorber/load limiter is then implemented for the seat structure so that it absorbs the energy of impact in an effective manner and below the tolerable limit for the occupant in a minimum stroke. Results show that for a designed stroke, the level of occupant lumbar spine injury would be significantly attenuated using this modified energy-absorber system.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Lumbar load attenuation for rotorcraft occupants using a design methodology for the seat impact energy-absorbing system

Moradi¹,

Beheshti

Lankarani

2012

Open Engineering

View full text Add to dashboard Cite

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“…On the other hand, the US military regulations regarding loads acting on the spine in combat helicopters define the permissible forces on the basis of the maximum acceleration value that is safe for the spinal column (14.5g). For a standard male dummy the permissible force level is as high as 9185N [18]. In the case of mining machinery operators this criterion should be verified by accurately adapting it to this group adapted to this particular group.…”

Section: Analysis Of Resultsmentioning

confidence: 99%

Method of operator safety assessment for underground mobile mining equipment

2018

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Abstract. The paper presents a method of assessing the safety of operators of mobile mining equipment (MME), which is adapted to current and future geological and mining conditions. The authors focused on underground mines, with special consideration of copper mines (KGHM). As extraction reaches into deeper layers of the deposit it can activate natural hazards, which, thus far, have been considered unusual and whose range and intensity are different depending on the field of operation. One of the main hazards that affect work safety and can become the main barrier in the exploitation of deposits at greater depths is climate threat. The authors have analysed the phenomena which may impact the safety of MME operators, with consideration of accidents that have not yet been studied and are not covered by the current safety standards for this group of miners. An attempt was made to develop a method for assessing the safety of MME operators, which takes into account the mentioned natural hazards and which is adapted to current and future environmental conditions in underground mines.

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