Research On Dynamics Of Oblique Collision Phenomenon

Collision vibration is closely related to People's daily lives,is also inevitable in the practical engineering application of dynamic phenomena.collision can be thought of as a special form of oblique collision and oblique collision vibration is the prevalent form of collision vibration.This paper bases on the oblique collision vibration system as the research object.revealing the oblique collision vibration system to exist the complicated nonlinear dynamics behavior.The main research and results of this paper are as follows:(1)The mechanical model of the two-body spring-mass oscillator oblique impact vibration system is simplified from the turbine blade with its own crown,and the existence condition of periodic motion is deduced;The impact surface and phase surface are selected as Poincaré cross sections,and the Jacobi matrix is obtained by using the semi-analytical method and then the nonlinear dynamic behavior of the oblique impact vibration system is investigated.The results revealed that the steady-state response of the oblique impact vibration system underwent such classical bifurcations as period-doubling bifurcation,Hopf bifurcation,and non-classical bifurcations as boundary shock and jump.(2)Taking the tilt Angle of the collision surface as the bifurcation parameter,the bifurcation diagram of the system's steady-state response changing with the tilt Angle of the collision surface is made.This paper analyzes the influence of the tilt Angle of the collision surface on the stability of the system.The results show that the tilt Angle of the collision surface has a great influence on the stability of the system,and there different collision frequency surface slope Angle of the effect on the stability of the system,which should be taken into account in engineering design.Meanwhile,combines with the time history diagram,the results demonstrates that the forward collision is a special form of oblique collision,and it is of general significance to study oblique collision.(3)The mechanical model of the oblique impact vibration system of a three-mass spring-mass oscillator is simplified from the wedge type shock absorber and a fourth order Runge-Kutta computer simulation program is written.Bifurcation diagrams,phase diagrams and Poincaré mapping diagrams with external excitation frequencies as bifurcation parameters are obtained by using Matlab software,and then the complex dynamic behavior of a three-body oblique impact vibration system is studied.The results suggestes that period-doubling bifurcation made the system's steady-state response transform among various types of periodic collision motions,Hopf bifurcation makes the system's steady-state response enter chaotic motion through quasi-periodic motion,and boundary shock makes the system directly enter into chaotic motion and other dynamic behaviors.(4)Bases on the time history diagram,phase trajectory,amplitude-frequency characteristic and mechanical energy variation diagram of the system,the damping performance of the oblique impact vibration system of three-mass is investigated.The results not only indicate that the collision could consume a certain amount of energy,so as to reduce the vibration amplitude and reach the purpose of reducing vibration,but also double side collision consume more energy and better than that of one-side collision.