Characterisation Of Wheel-Rail Noise In Ballastless Track Under High Frequency Vibration

Railways are becoming more and more popular as an efficient and convenient way to travel,but as the speed of trains accelerates,the ensuing railway noise problem also affects people’s normal life,and railway noise is dominated by wheel track noise,so it is vital to analyse and predict and reduce wheel track noise.In this thesis the train wheels are LMA type treads and the rail plate form is CRTS II type plate rail plate,as a research object,the research history of wheel-rail noise at home and abroad respectively is introduced.After understanding the basic knowledge of structural conductivity,the wheel and rail systems are built in the finite element software ANSYS according to the actual dimensions,and the unit force is applied to the nominal contact point between the wheel and the rail.The results show that the conductivity amplitude in this thesis is in basic agreement with the conductivity amplitude obtained from the reference literature,i.e.the correctness of the finite element model is verified.Subsequently,we will discuss the wheel rail coupling and obtain the wheel rail force at frequencies between 100 Hz and 4000 Hz.Input the wheel-rail force in the frequency domain into the finite element model,The vibration response of wheel/rail can be obtained.In addition,to introduce the basic knowledge about acoustics,and theoretical equations of sound radiation characteristics,etc.,in the acoustic software LMS Virtual.lab to establish the acoustic model of the wheel and track system,and verify that the established boundary element model is correct.The results show that the maximum sound pressure level of the wheel track is 88.12 d B(A)at the standard point C at a speed of 300 km/h.When the frequency is below 2500 Hz,the rail has the largest contribution to the total noise,and from 2500 Hz to 4000 Hz,The maximum contribution from the wheels is at 2000 Hz to 4000 Hz.Since the CA mortar modulus of elasticity has reached7000 MPa,the noise contribution from the rail slab is always lower than that from the wheels and rails.By changing some of the parameters in the model to compare the effect on the noise,firstly the wheel track noise at 200 km/h,300 km/h and 400 km/h was analysed and it was found that as the train speed increased,the maximum sound pressure level of the wheel track gradually increased.By changing the rail mass,vertical stiffness and damping of wheel panels and fasteners,it was found that the rail mass has an impact on wheel rail noise at low and high frequencies;The thickness of the wheel panel is negatively correlated with wheel noise;The greater the vertical stiffness and damping of the fastener,the smaller the maximum sound pressure level of the wheel rail.In order to facilitate the continuation of the subsequent vibration and noise reduction research,the acoustic contribution of the wheel and rail components were analysed,and the results showed that: the sound pressure contribution of the wheel in descending order is the tread,width plate,rim,rim,hub,and the sound pressure contribution of the rail in descending order is the rail waist,rail top,rail bottom.