Research On Nonlinear Dynamics Of Vehicle Absorber With Gap Including Elastic Contact

In the field of machinery,errors in design,production and assembly can cause gaps in equipment.In addition,under the influence of external excitation force,there will be gaps between equipment parts due to collision and wear during work.This has an impact on the durability of the equipment.In severe cases,it will cause damage to the mechanical facilities and even threaten the safety of the operator.Therefore,in order to ensure the stable operation of the equipment in the most ideal state,the vibration control problem of the system with gaps is very important.In this paper,the theoretical research will be carried out through a class of passive control devices.This type of nonlinear energy trap is a kind of vibration damping equipment in engineering practice.Its vibration absorption performance is an important factor affecting the dynamic characteristics of mechanical systems and can be widely used in various fields.First of all,the engineering background of this paper is divided into three space states of two sides boundary and two sides gap according to the vibration reduction system on the actual locomotive and vehicle bogie.In addition,the excitation force and vibration amplitude are the basis,and the motion collision boundary is selected as the prerequisite for the existence of the response periodic solution.At the same time,the periodic motion and energy transfer process of the system are described.After the disturbance variable is added,the system is subject to external interference,and the response mechanism is determined by the boundary state at this time.According to the obtained Poincaré cross-section projection and iterative matrix to determine the convergence and stability of the system,the numerical solution of the ordinary differential equation is obtained by using the approximate analytical method and the variable step size fourth-order Runge-Kutta method.Then use MATLAB software to program and calculate,select appropriate system parameters for dynamic simulation.It shows that the system experienced stable bifurcation,toroidal bifurcation,Hopf bifurcation,Hopf-flip bifurcation,Y.Neimark-R.J.Sacker bifurcation and paroxysmal chaos(crisis).Characteristics,make a theoretical description of the state of the formation of chaotic motion.Secondly,the compression system is simplified by the pre-compression spring placed on the bogie.The tension system is a second-order spring shock absorber,which needs to control the maximum height limit of the spring.Among them,the tensile model of the system analyzes the effects of dynamic behaviors such as periodic motion and system stability from the perspective of simple harmonic excitation and vibration amplitude and frequency characteristics.So as to avoid serious consequences caused by excessive vibration.For the compression model,the low,medium and high frequency bands are selected as the parameter range respectively,which is used as the connection for the subsequent theoretical analysis,and at the same time,it provides a certain feasibility for the parameter optimization design,and also finds out the improvement of the overall efficiency of the critical state with gap Effective Ways.Finally,bilateral clearance conditions are simulated for the EMU series,such as the dampers on the 380 bogies in CRH5.A two-sided collision system model with gap flexible constraints is established,and the differential equation of the system is obtained by force analysis of the physical model.Using the boundary conditions of the disturbed motion,the expression of the initial value mapping of the system on the Poincaré section(low-dimensional subspace)and its Jacobi matrix are derived.Use Floquet theory to analyze the bifurcation boundary conditions existing in the system,and then conduct numerical simulation experiments.Describe the mechanical movement of the system and the characteristics of bifurcation and chaos,and find out the nonlinear dynamic behavior of the system under the influence of different parameter intervals(damping stiffness,mass ratio and gap amount).It is found that the path of the system to chaos through classical bifurcations and non-classical bifurcations provides theoretical assistance for the vibration reduction design of rail vehicle systems.