Simulation And Optimization Of Aircraft Nose Landing Gear Shimmy

In the process of nose landing gear design, the shimmy problem is always confronted by thedesigners. Because of its big influence to the safety of landing, the analysis and research of NLGshimmy problem becomes an important mission for the aircraft designers. In the past, a lot workconcerning this problem has been done widely and profoundly by domestic and overseasresearchers. But most of the research was focused on the qualitative analysis under variousassumptions, while the quantitative analysis and simulation based on engineering software wasdone rarely. To the engineers, a simple、user-friendly simulation model which can be used tosimulate the NLG shimmy expediently with the given parameters is more important andmeaningful.Considering the small influence of the nonlinear parameters and the difficulty to construct anonlinear model, linearization methods are adopted. Both the fuselage and the strut are seen asflexible, simultaneous ordinary differential equations and the normal form are concluded. UsingSimulink of Matlab, the simulations are done respectively under rigid assumption and flexibleassumption with the parameters of a type of aircraft, and the results are compared. The comparingis done mainly to determine the respective influence of some important parameters such as: taxingspeed、structural flexibility、nonlinear factors、trail、damping and inflation pressure.In order to get the optimal parameters for the sake of deterring NLG shimmy, an optimization ismade through the combination of a M script and the simulation model, while damping is thedesign variable.The simulation and optimization can be carried out successfully using the model structured inthis paper with given parameters. The simulation is quick、simple、reliable and user-friendly, andthe model can be applied to the NLG design when the shimmy problem is considered.