Application Of Improved Pseudo-Excitation Method In Coupled Vehicle-structure Systems

With the continuous development of high-speed railway technology,the key mechanics of the coupling between rail vehicles and structures has attracted the attention of scholars.Existing random vibration related work in this field mainly uses low-degree-of-freedom rail vehicle rigid body dynamics models and simple track/bridge models.Obviously,it is impossible to accurately analyze the dynamic behavior of train bodies,frames,wheel sets and other components and actual track bridges under different vibration frequency ranges.This is mainly due to the low efficiency of the existing random vibration analysis methods,and the fine finite element train and structure coupling model often has more than one million degrees of freedom,which brings great challenges to numerical calculations.In response to the above problems,this article has carried out the following research work:Firstly,based on the framework of the pseudo excitation method,an improved algorithm for structural random vibration analysis under non-stationary random excitation is proposed.Bring the pseudo excitation as external excitation into the Duhamel integral formula,and we can get the pseudo response represented by the integral.We can discrete this integral on the time axis and use the rectangular formula to calculate the definite integral.This algorithm only needs to multiply the impulse response matrix of the system obtained in advance with the external excitation to obtain the pseudo response value of the system.Because it is not necessary to calculate every step on the time axis when solving the random vibration response of the structure,only the time nodes of interest are calculated to obtain accurate calculation results,and the calculation efficiency is greatly improved.Through the analysis of specific examples,the calculation accuracy and efficiency of this algorithm are verified.Secondly,the improved algorithm proposed is applied to the vehicle-track coupling system.Because the vehicle-track coupling analysis dynamic point model used in the coupling analysis is a time-varying system,so we split it into two parts: constant and time-varying.The timevarying part-track of the vehicle-track coupling system is calculated by the time-integration algorithm,and the non-time-varying part is calculated by the improved algorithm.In this paper,the improved algorithm is derived to solve the random vibration response of the vehicle-track coupling structure,and the accuracy of the improved algorithm for solving the time-varying system is analyzed in combination with specific examples.Finally,a method for solving the random vibration problem of a large-scale finite element vehicle-bridge model is developed based on the pseudo excitation method.The mode decomposition method is used to reduce the order of each structural member of the coupling system,and then the coupling between them is realized in the modal space.We deduced the coupled vibration equations of the multi-group vehicle body,frame,wheel set,and bridge structure in the modal space,and analyzed the random vibration response of the vehicle bridge by taking the eight-carriage train passing the bridge as an example.