Theoretical And Experimental Research On Reducing Vibration Of Damped Wheels/Rail

With the promotion of railway's speed in china, many problems of environmental noise and vibration caused by it are drawing more and more attentions. So how to solve these problems are particularly important. From the noise and vibration source, structure of constrain damping is applied to wheel/rail, in order to reduces noise and vibration from the source, and achieves good results.The main contents of this paper are as follows:1. On the basis of the characteristics of constrain damping structure and the environmental quality of railway as well, material of type ZN03 is chosen as damping layer and aluminum as constrain layer. Damped Wheel/rail samples are manufactured, a detailed illustration of the manufacture step of them is presented.2. Vibration performance of damped wheel/rail is modally analyzed with ANSYS, which shows the main characteristics of vibration and the Primary noise radiation source in them. Different laying sites are analyzed about the effect on reducing damped wheel vibration. Then the optimal structure is selected by comparison of vibration acceleration and structural loss factors.3. 6 types of Damped Rails are designed; different thickness of damped layer, material and thickness of constrained layer are analyzed respectively about the effect on reducing rail vibration. Then structural loss factors of these 6 types are calculated based on FEM and the optimal style is selected by comparison.4. Wheel/rail hanged elastically in the laboratory, the amplitude of vibration transfer function for damped wheels/rails are tested by using force-instrumented hammer, acceleration transducer, electricity amplifier, digital data decoder and software DASP, which analyze vibration transfer properties respectively. By self-made single pendulum exciting, damped wheels are tested on acceleration-frequency response. With self-made single pendulum and sound level meter, 1/3 octave band spectrum for wheel noise is analyzed. The experiment results show that the damped wheel/rail have an ideal effect on reducing noise and vibration.The main conclusions of this paper are as follows:1. The vibration model shape of damped wheel in the range of 0-5000HZ is as same as standard wheel, shows as viggler vibration of tread, axial and radial vibration of web, portfolio vibration of tread and web. With the same model, relatively small changes of resonance frequency have been happened with the comparison between damped and standard wheel, the value of changes is increasing with the size of laying.2. The comparison between acceleration-frequency response curve of different conditions shows that for damped wheel, the effect on reducing vibration of damping layer attached to two sides is much better than to one side, and the more the attachment size, the better the effect. Most structural loss factors of damped wheel are more than 0.01, as factors of standard wheel are between 0.0001 and 0.0006, which shows that the effect on reducing vibration of damping layer is good, and is better with more size of laying.3. The test of transfer function for damped wheel shows that between 1200-5000HZ, the amplitude of vibration transfer function for damped wheel is much lower than standard wheel, and is lower with more size of laying. Wheel of damping layer attached to two sides is the most prominent in the text. In condition of single pendulum exciting, the vibration acceleration of damped wheel is much lower than standard wheel. This conclusion is consistent with the analysis of transfer function. And the analysis of 1/3 octave band spectrum shows that the effect of reducing noise is obviously, especially between 300 and 5000HZ.4. The vibration model shape of damped rail in the range of 0-5000HZ is mostly consistent with standard rail, shows as horizontal, vertical and viggler vibration, and the viggler vibration also reflects as horizontal and vertical vibration. Between 0- 1500HZ, rail vibration mainly shows as horizontal and vertical vibration of rail web while more than 1500HZ, the vibration shows as all the kinds of vibration, but still horizontal and vertical vibration of rail web is the main. Under the same vibration model, because of additional quality, relatively small changes of resonance frequency have been happened. The comparison of vibration model pictures between damped and standard rail shows that according to the main frequency, the largest vibration displacement of damped rail's vibration model has obviously decreased.5. The comparison between acceleration-frequency response curve of 6 different kinds of damped wheel's structure shows that after laying constrain damping material, standard rail's largest vibration acceleration has obviously decreased and its structural loss factor is mainly more than 0.01,all of these shows a good effect of reducing vibration. Also we can see from the 6 different structure models that the effect is better with an increase of constrain damping laying's thickness, constrain laying's hardness and elastic modulus.6. The test of transfer function for damped and standard rails shows that the resonance peaks of them are distributed over the full range; the amplitude of vibration transfer function for damped rail web is much lower than standard wheel web, so it has a good effect in the website but not obviously in head and root sites.