The Dynamics Of Nonsmooth System And Its Application In Vehicle Engineering

Nonsmooth factors are existing in mechanical systems, and it often causes discontinuousand nonlinear by clearance, leads to complicated dynamics behavior. In this case, researchingon nonlinear dynamics of nonsmooth systems is of significance. With the development ofChina railway, it brings up many comprehensive advantages, such as wheel-rail collision,the permitted speed and the comfort and running safety. For the improving of highspeed vehicle dynamics, it puts forward a series of subjects to researchers.Wheel-rail impact system can considered as a two-degree-of-freedom vibro-impactsystem with bilateral rigid constraints, the wheel-rail is a typical system with clearance. Thispaper established a dynamic model of two-degree-of-freedom with clearance and variablestiffness spring, and dynamic model of two-degree-of-freedom with clearance and dry friction.By choosing appropriate parameters, stability and bifurcation of vibro-impact system aresimulated through numerical simulation, and reveals the system exists chaotic transition. Theresearch can provide theoretical basis for the study of wheel-rail collision dynamics.This paper aims at carrying out deep research on wheel-rail collision dynamics, based onthe modern theory of vehicle-track coupling dynamics, using the analysis methods of modernnonlinear dynamics, derivates the nonlinear factors between wheel and rail, especially thederivation of wheel-rail creep rate and the nonlinear conversion of wheel-rail creep force.Select different mathematical descriptions, two rigid wheel-rail collision model is set up, trackare considered to be rigid in the processes of modeling. Analyzing the bifurcation and chaosof wheel-rail collision with Runge-Kutta numerical method. Make a concrete analysis ofwheel-rail dynamic system, we can get stability and bifurcation at different speeds, includingperiodic motion, symmetric and asymmetric periodic orbit, pitchfork bifurcation, periodicdoubling bifurcation and chaotic motion. Finding out the stable and unstable stage of velocityinterval, and seek out different bifurcation point at specific speed. To explore the complexdynamic behavior of wheel-rail system under different friction coefficients. Research showsthat with the increasing of wheel velocity and exceeds a critical value, collision occursbetween wheel and rail, and then into chaotic region. At low speed, the friction coefficienthave greater impact on the movement of wheel-rail system.