Random Vibration Response Analysis Of Aircraft Ground Sliding

The random vibration problem in engineering is usually the response problem of deterministic system under random excitation.The response problem of aircraft ground shifting movement belongs to this type of response problem.When the aircraft is moving at a variable speed,the random excitation of the road surface is non-stationary.In the non-stationary process,the power spectrum concept will no longer be applicable,but the non-stationary random excitation can be expressed by evolutionary random excitation,and the power spectral density of the original stationary random excitation is utilized to represent the response-related characteristics of non-stationary random excitation.In this way,the system random excitation response problem is transformed into transient response problem under deterministic excitation by evolutionary spectral method.An aircraft is a complex mechanical structural system that is typically modeled during actual research.In this paper,considering the pitching motion of the fuselage and the elasticity of the fuselage,the aircraft is simplified into a four-degree-of-freedom rigid body model and an N+4 degree-of-freedom elastomer model.The time-varying linear dynamic differential equations of each model are listed,and the evolution process of each model and the derivation process of related statistics are given.Firstly,the response of the rigid body model under different accelerations is numerically analyzed by evolution spectrum method,and then compared with the response of the elastic body.Finally,the response of the two types of models under the action of lift and pitch moment is studied,and the mean square and variance of the response of the aircraft's center of gravity under the combined action of road excitation and lift and pitch force are obtained.The landing gear adopts a nonlinear model,and the equivalent linearization parameters are solved iteratively.