Innovative Anti Crash Absorber for a Crashworthy Landing Gear
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Innovative Anti Crash Absorber for a Crashworthy Landing Gear Michele Guida & Francesco Marulo & Bruno Montesarchio & Massimiliano Bruno
Received: 8 July 2013 / Accepted: 19 September 2013 # Springer Science+Business Media Dordrecht 2013
Abstract This paper defines an innovative concept to anti-crash absorber in composite material to be integrated on the landing gear as an energy-absorbing device in crash conditions to absorb the impact energy. A composite cylinder tube in carbon fiber material is installed coaxially to the shock absorber cylinder and, in an emergency landing gear condition, collapses in order to enhance the energy absorption performance of the landing system. This mechanism has been developed as an alternative solution to a high-pressure chamber installed on the Agusta A129 CBT helicopter, which can be considered dangerous when the helicopter operates in hard and/or crash landing. The characteristics of the anti-crash device are presented and the structural layout of a crashworthy landing gear adopting the developed additional energy absorbing stage is outlined. Experimental and numerical results relevant to the material characterization and the force peaks evaluation of the system development are reported. The anti-crash prototype was designed, analysed, optimized, made and finally the potential performances of a landing gear with the additional anti-crash absorber system are tested by drop test and then correlated with a similar test without the anti-crash system, showing that appreciable energy absorbing capabilities and efficiencies can be obtained in crash conditions. Keywords Crash landing . Composite structure . Shock absorber
1 Introduction One of the main requirements to be met for a military aircraft, mainly due to a helicopter, is able to withstand a crash at high-speed vertical impact (12.8 m/s−1), without loss of the crew. Most of the energy that develops during the crash (60 %) is absorbed by the landing gear equipped with special shock absorbers that have complicated construction, at the expense of weight and maintainability. The landing gear has significant importance in the design of an airplane or M. Guida (*) : F. Marulo Department of Industrial Engineering, Aeronautical Section, University of Naples “Federico II”, Naples, Italy e-mail: [email protected] B. Montesarchio : M. Bruno Magnaghi Aeronautica, Aeronautical Industry, Napoli, Italy
Appl Compos Mater
helicopter for the functional aspect is that the structural changes it needs to secure the ground and absorb the landing impact. The stresses to which it shall be given a landing gear are significant and therefore the design of its structural parts requires a very thorough study of the forms to meet the requirements of weight, strength and rigidity. The materials in this type of composite structures, as it appears, would find their natural application if it were not for the technological difficulties encountered in implementing the structures of complex shapes that characterize, as mentioned, the landing gear. The shock
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