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

Download

index.pdf

Date

2018

Author

Öztürk, Gülce

Metadata

Show full item record

Item Usage Stats

190
views

80
downloads

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

Suggestions

OpenMETU
Core

Control of a helicopter during autorotation Şansal, Kaan; Konukseven, Erhan İlhan; Nalbantoğlu, Volkan; Department of Mechanical Engineering (2018) Autorotation is a maneuver that requires no power and it is used in rotorcrafts when last operating engine is lost. It is an extremely complex state of flight and landing successfully after total power loss requires considerable skill. Main idea behind autorotation is that, by descending with a controlled rate, available potential energy is used as a source that turns main rotor at desired speed for providing thrust and flight control. Just before touchdown, ground speed and descent rate must be reduced for...
Shape optimization of helicopter subfloor intersection element under crash loading Türe, Mustafa Okan; Dağ, Serkan; Department of Mechanical Engineering (2017) The aim of the crashworthiness is maintaining a survivable space for occupants and absorb crash energy as much as possible. The statistics showed that 85% of all rotorcraft accidents can be survivable. Thus, crashworthy design has direct effect on occupants' survival. This thesis analyses a longitudinal beam and lateral frame intersection point on helicopter subloor. Analysis is performed on ABAQUS Dynamic/Explicit solver. Analysis includes high deformation levels, self-contact and nonlinearities. 110 kg ma...
A Comparison of model following control systems for helicopter flight control near hover Okçu, Ilgaz Doğa; Kutay, Ali Türker; Department of Aerospace Engineering (2015) Helicopters are complex, coupled dynamic systems with unstable behavior. Countless studies have shown that decoupling the helicopter flight dynamics greatly reduces pilot work load and increases the handling qualities. Design guidelines such as Aeronautical Design Standard 33E-PRF (ADS-33E), which are developed as a means of measuring the handling qualities of a given helicopter, emphasizes that coupling between pitch, roll, yaw and heave degrees of freedom are undesired. ADS-33E also gives flight dynamics ...
Separation simulation for helicopter external stores and generation of safe separation envelopes Kapulu, Özge; Tekinalp, Ozan; Department of Aerospace Engineering (2015) In many aerospace applications, simulations are used to predict the behavior of the flight vehicle and reduce the number of flight tests required. In this thesis modeling and development of separation simulation tool for helicopter external stores is carried out. Detailed explanations of mathematical modeling, procedure of store separation analysis and collision detection approach from flight dynamics point of view are presented. The nonlinear mathematical model of armed configuration of Black Hawk helicopt...
Design of a sled test fixture for civilian helicopter seats Seçgin, Alican; Gökler, Mustafa İlhan; Department of Mechanical Engineering (2019) Crashworthiness of civilian helicopter seats are important since it affects the survivability of occupants. For this reason, there are some established criteria for the authorization of civilian helicopter seats. In this study, vertical crash criterion and floor deformation criterion, which are stated on CS 29.562 by European Aviation Safety Agency (EASA), regarding to civilian helicopter seats are investigated. The Simplified Helicopter Seat (SHS), the Interchangeable Floor Deformation Unit (IFDU), and Sle...

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.