Shimmy can reduce the service life of the nose landing gear, affect ride comfort, and even cause fuselage damage leading to aircraft crashes. Taking a light aircraft as the research object, the torsional freedom of la...Shimmy can reduce the service life of the nose landing gear, affect ride comfort, and even cause fuselage damage leading to aircraft crashes. Taking a light aircraft as the research object, the torsional freedom of landing gear around strut axis and lateral deformation of tire are considered. Since the landing gear shimmy is a nonlinear system, a nonlinear mechanical model of the front landing gear shimmy is established. Sobol index method is proposed to analyze the influence of structural parameters on the stability region of the nose landing gear, and Routh-Huritz criterion is used to verify the reliability of the analysis results of Sobol index method. We analyse the effect of torsional stiffness of strut, caster length, rated initial tire inflation pressure, rake angle, and vertical force on the stability region of theront landing gear. And the research shows that the optimization of the torsional stiffness of the strut and the caster length of the nose landing gear should be emphasized, and the influence of vertical force on the stability region of the nose landing gear should be paid attention to.展开更多
A more reliable parametric shimmy analysis model taking the elasticity of strut, the elasticity of damper linkage system and the influence of shimmy damping into consideration is set up in this paper. The Multiple Sc...A more reliable parametric shimmy analysis model taking the elasticity of strut, the elasticity of damper linkage system and the influence of shimmy damping into consideration is set up in this paper. The Multiple Scales Method is utilized to obtain the expressions of stability condition and transition curve under the conditions of non resonant case, principal parametric resonance and combination resonance respectively. The parametric shimmy analysis for a real type of aircraft is carried out based on the perturbation analysis results, and the stability chart and critical taxiing velocities of two types of aircraft in the case of principal parametric resonance are given. It is indicated that there exist two critical taxiing velocities near which parametric shimmy is susceptible to occur, while the landing gear system is stable when taxiing velocity is far from them. This characteristic makes the parametric shimmy distinct from the shimmy in general case. Because few previous studies of nose gear shimmy have dealt with parametric shimmy problem, the results given in this paper provide useful reference for aircraft design and maintenance.展开更多
文摘Shimmy can reduce the service life of the nose landing gear, affect ride comfort, and even cause fuselage damage leading to aircraft crashes. Taking a light aircraft as the research object, the torsional freedom of landing gear around strut axis and lateral deformation of tire are considered. Since the landing gear shimmy is a nonlinear system, a nonlinear mechanical model of the front landing gear shimmy is established. Sobol index method is proposed to analyze the influence of structural parameters on the stability region of the nose landing gear, and Routh-Huritz criterion is used to verify the reliability of the analysis results of Sobol index method. We analyse the effect of torsional stiffness of strut, caster length, rated initial tire inflation pressure, rake angle, and vertical force on the stability region of theront landing gear. And the research shows that the optimization of the torsional stiffness of the strut and the caster length of the nose landing gear should be emphasized, and the influence of vertical force on the stability region of the nose landing gear should be paid attention to.
文摘A more reliable parametric shimmy analysis model taking the elasticity of strut, the elasticity of damper linkage system and the influence of shimmy damping into consideration is set up in this paper. The Multiple Scales Method is utilized to obtain the expressions of stability condition and transition curve under the conditions of non resonant case, principal parametric resonance and combination resonance respectively. The parametric shimmy analysis for a real type of aircraft is carried out based on the perturbation analysis results, and the stability chart and critical taxiing velocities of two types of aircraft in the case of principal parametric resonance are given. It is indicated that there exist two critical taxiing velocities near which parametric shimmy is susceptible to occur, while the landing gear system is stable when taxiing velocity is far from them. This characteristic makes the parametric shimmy distinct from the shimmy in general case. Because few previous studies of nose gear shimmy have dealt with parametric shimmy problem, the results given in this paper provide useful reference for aircraft design and maintenance.
