Research On Vibration Response Characteristics Of Axle Box Under The Influence Of Out-of-round Wheel

Wheel irregularity is a common defect form in train operation,which will aggravate the interaction between wheel and rail,resulting in strong vibration of vehicle system components.Under this kind of vibration,noise will be produced which affects the comfort of the passengers,and fatigue damage of key components will be caused,which eventually leads to serious safety accidents such as train derailment.Therefore,many manufacturers and research institutions pay attention to the research and solution of wheel irregularity,and would like to develop a real-time monitoring system of wheelset condition based on axle-box vibration acceleration signal.Therefore,it is necessary to study the relationship between wheel irregularity excitation and axle-box vibration response,so as to obtain the characteristics of wheel fault signal.Although many scholars have done relevant research on the dynamic behavior of wheel polygon and wheel flat before,most of them analyzed the dynamic influence caused by the irregularity of wheels for a particular vehicle type,and there is a lack of summary of general rules,and few detailed studies on resonance characteristics have been conducted.In this thesis,the following research work is carried out:(1)By using SIMPACK dynamics software and ABAQUS finite element software,the rigid flexible coupling vehicle system dynamics model is constructed,and the four wheelsets and corresponding axle boxes are configured with different rigidity and flexibility,so as to facilitate the comparison of rigid model and flexible model.(2)The modes of wheelset axle box in free state and vehicle assembly constraints are compared and analyzed.A new excitation loading method is proposed to study the resonance characteristics of wheelset axle box,and the resonance responses of the vertical wheel-rail force and axle box vibration under different rigid and flexible combinations of wheelset axle box are obtained.Based on the resonance response,the relationship between different rigid and flexible combinations is explored,and the causes of each formant are analyzed.(3)Besides the wheelset itself and the axle box structure,the factors that easily affect the resonance characteristics of wheelset axle box are explored.The results show that the mass of the axle box,the moment inertia of the axle box around the x-axis and the position of the center gravity of the axle box have great influence on the resonance characteristics of wheelset axle box,while the stiffness and mass of the primary spring have little influence on the resonance characteristics.(4)The general law of vibration acceleration response of axle box under the influence of different types of wheel irregularity is discussed.The simulation results show that the frequency domain response characteristics of the vibration,without separation between wheel and rail,are affected by the resonance while retaining the frequency domain characteristics of the excitation,and the amplitude will be amplified in different degrees at different frequencies.When the wheel rail separation occurs,the frequency response characteristics of the vibration show that resonance peaks are formed at natural frequencies.