Design and analysis of fixed load crushable column type energy absorbing mechanism for a helicopter seat

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2018

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Öztürk, Gülce

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Crashworthiness is the survivability of occupants inside a vehicle during a crash. In helicopters, crashworthiness is ensured by three subsystems; the landing gear, floor structure and the seats. Because of the critical role of the seats in helicopter crashworthiness evaluation, dynamic performance of the seat has to be studied in depth. There are different regulations in which requirements of survivable loads and crash conditions are defined. In this respect, a seat that is used in helicopter should be certified by complying applicable regulations and should satisfy the safety of the occupants during a crash. In order to comply with the regulations, a seat must absorb some portion of the crash energy and reduce the load that comes to the occupant. In this thesis, a crushable absorber system is designed to analyze the dynamic behavior and performance of the helicopter seat. The mechanism of the absorption system makes use of the crash energy to plastically deform the aluminum material of the seat legs. The designed helicopter seat is analyzed using the explicit finite element method to evaluate how the seat energy absorbing mechanism works. Dynamic simulations are performed in ABAQUS by crashing the seat to a fixed rigid wall. To simulate the plastic deformation, true stress-strain curve of the aluminum material of the seat leg has been used. Time response results are filtered to calculate the meaningful g loads which incur damage to the occupants. Analyses are done with and without the absorption mechanism in order to see the effectiveness of the mechanism on the human survivability by comparing the g loads on the seat bucket with the acceptable loads given by European Aviation Safety Agency (EASA). Simulation results are compared and energy absorption mechanism has been showed to be effective for reducing the impact loads that comes to the occupant during crash.

Subject Keywords

Helicopters., Helicopters, Helicopters

URI

http://etd.lib.metu.edu.tr/upload/12622631/index.pdf
https://hdl.handle.net/11511/27525

Collections

Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

G. Öztürk, “Design and analysis of fixed load crushable column type energy absorbing mechanism for a helicopter seat,” M.S. - Master of Science, Middle East Technical University, 2018.