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Optimization methods for helicopter landing gears
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Lopez, Cédric (2007) Optimization methods for helicopter landing gears. PhD thesis Conception, LSIS, ENSAM 2007ENAM0038 p.175. AbstractRecent experimental studies of helicopter hard landing (landing speed higher than 2 m/s speed) have highlighted that the mechanical coupling between the aircraft structure and landing gears lead to tail boom oscillations which first bending mode occurs at low frequencies. These tail boom oscillations generate mechanical constraints between the cabin and tail boom and affect structural integrity. To avoid such issue, a passive solution was implemented. It consists of
stiffening the interface between the cabin and tail boom. However, it involves significant mass penalty and interferes with anti-vibratory systems which are designed based on the aircraft natural frequencies. An alternative solution consists of landing gear dynamic behavior control. Based on these observations, the passive and active optimization methods of landing gears are presented. The common objective of the different methods is to minimize the forces on the tail boom which are created by ground impact. Based on both theoretical and experimental studies, this research describes first the causes of the problem. Then, the physical concepts behind the aircraft landings are analyzed using analytical and multibody dynamics approaches. Finally, the landing gear optimization parameters are analyzed and identified. Passive and semi active methods are designed and validated by experiments performed on a demonstrator mechanically equivalent to the studied helicopter.
| Item Type: | PhD Thesis (PhD) |
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| Thesis Supervisor: | Barraco, André |
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| Date: | 20 December 2007 |
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| Board of examiners: | Guinot, Jean-Claude and Dufour, Régis and Sename, Olivier and Barraco, André and Malburet, François and Krysinski, Tomasz |
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| Ecole Doctorale: | ED 432 ECOLE DOCTORALE SCIENCES DES METIERS DE L'INGENIEUR |
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| Discipline: | Conception |
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| Collection (Fonds): | ENSAM |
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| Institution: | ENSAM |
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| Department: | LSIS |
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| Subjects: | 4. Materials Science, Mechanics and Mechanical Engineering |
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| Uncontrolled Keywords: | Atterrissage dur, Commande, Couplage mécanique, Démonstrateur, Excitation, Minimisation, Mode glissant, Multi-corps, Non linéaire, Optimisation, Oscillations, Passif, Puits de chute, Pid, Quadratique, Recalage, Semi-actif, Control, Cross check, Demonstrator, Drop test bench, Excitation, Hard landing, Mechanical coupling, Minimization, Multibody, Nonlinear, Optimization, Oscillations, Passive, Pid, Quadratic, Semi active, Sliding mode |
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