Prediction And Analysis Of Vibration And Sound Radiation Of Floating Slab Track

With the development of the urban rail transit system,it received extensive social concern that a series of vibration and noise problems caused by rail transit.Steel spring floating slab track has been widely used in subway lines,offers improved performance.But it also brings a series of noise problems.The research purpose of this thesis is to establish the vibration and sound radiation prediction model of the steel spring floating slab track.The prediction model provides an accurate external sound source for predicting the noise inside the train,assistance for the parameter design of the floating slab track,and a feasible method for reducing the noise of the floating slab track.Considering the infinite and periodic characteristics of floating slab track,and treating wheels to be rigid,a vibration and sound radiation prediction model of the floating slab track was established,with the using of 2.5D finite element method and boundary element method(2.5D FEM-BEM).The characteristics of vibration and sound radiation of the floating slab track were analysed.The main research work of this thesis is summarized as follows:(1)The thesis has used the modal superposition method which based on thin plate theory to establish the prediction model of discrete supported floating slab.The modal superposition method based on plate theory has been verified by comparing with the finite element method.(2)The 2.5D FEM and the periodic structure theory were used to establish vibration model of the infinite floating slab.The vibration model was uesd to predict the vibration response of floating slab track under harmonic load and the effect of load movement was also taken into account.(3)The wheel-rail force under the wheel-rail roughness spectrum was calculated by the‘moving irregularity method’,then,a complete vibration and sound radiation prediction model of floating slab was established.(4)The 2.5D BEM was used to calculate the sound radiation of rail and floating slab in tunnel and on the ground.In the caculation,the car body,tunnel and bridge were counted as acoustic rigid boundary.When calculating the sound radiation of the floating slab,the changes in its vibration along the lateral direction should be considerd.The model was used to research the influence of wheel/rail force speed on the sound radiation of rail and floating slab,and to compare the difference of the sound radiation of floating slab track systems between bridge and in tunnels.(5)An ordinary non-ballasted track model has been established,and the vibration and sound radiation characteristics of the two types of tracks(ordinary non-ballasted track and floating slab track)had been compared.(6)The established vibration and sound radiation prediction model was used to investigate the effects of sound absorbing materials,vibration isolator parameters and floating slab parameters on the vibration noise of the floating slab track.(7)The MALTAB program was written and incorporated into the railway wheel-track vibration and sound radiation prediction software(WTVNS).