Study On Multi-body Dynamics Simulation And Analysis Of Three Types Of Friction Damping Devices For Railway Freight Cars

With the increasing speed of railway wagons,it is difficult for vehicles to maintain good dynamics in a complex vibration environment,so the smoothness of vehicle operation has put forward higher requirements.Vibration damping device plays an important role in maintaining the smoothness of vehicle operation,the existing variable friction damping device,although the vibration damping performance is stable,but easy to wear and insufficient anti-ringing stiffness;normal friction damping device vibration damping force is constant,can not meet the no-load and full-load conditions of vibration damping requirements;double-action friction damping device is a new type of vibration damping device that combines the advantages of normal friction damping device and variable friction damping device.Based on the improved structure of the double-acting friction damping device,this thesis builds a virtual prototype and simulates the actual operation of the three types of damping devices in the Recur Dyn multi-body dynamics simulation platform,and solves the comparative analysis of the dynamic damping performance of the normal friction,variable friction and double-acting damping devices under different excitation line conditions.The main research elements of this thesis are as follows:Firstly,the structural composition and working principle of three types of railway wagon bogie spring damping devices,namely normal friction,variable friction and double acting,are studied and analysed,and the relative friction of the three damping devices is theoretically calculated by means of analytical calculation,and the force analysis of the main force-bearing components,the inclined wedge,is carried out.Secondly,a virtual prototype is built using RecurDyn multi-body dynamics simulation software,a suitable modelling environment is set up,and suitable contact and constraint collision relationships between the clearance mechanism and the drive and load are imposed to reproduce the working conditions of the damping device in actual operation.In order to ensure the accuracy of the subsequent simulation results,static balance tests were conducted on the three vibration damping devices for empty and heavy vehicles respectively.By comparing the virtual prototype test data with the experimental data,the maximum deviation of spring height and wheel-rail vertical force in the initial state is less than 3%,which meets the reliability requirements of the simulation test model.Finally,a total of 96 sets of simulation tests were set up under nodding and floating and sinking agitation conditions with the given criteria.The minimum wheel-rail vertical force,the frictional force between the tilting wedge and the side frame,and the maximum compression of the spring are used as indicators for evaluating the vibration damping performance of the vibration damping device under different load conditions of empty and heavy vehicles,different amplitudes of 1A,0.5A and 0.7A,different frequencies of 1F,0.5F and 0.7F,and different primary and secondary friction coefficients of μ,μ+0.1 and μ+0.2.The vibration damping performance of the three vibration damping devices is compared and contrasted.By analysing the order of the damping force provided by the three vibration damping devices,the variation of frequency F,amplitude A and friction coefficient on the wheel-rail vertical force,the maximum compression of the spring and the friction between the inclined wedge and the side-frame are obtained.In the case of an empty vehicle,only the normal friction damping spring provides the damping force;in the case of a heavy vehicle,the normal friction and variable friction damping springs provide the damping force together,so that the relative friction coefficients are within the ideal range for both empty and heavy vehicles,and the vehicle vertical dynamics is better.It is verified that the double-acting friction damper has a significant effect on vibration shock mitigation,and also provides a theoretical reference for the practical application of the double-acting damping device,providing an effective and reliable research method.