| In order to alleviate traffic congestion and change the urban transportation development mode,giving priority to the development of public transportation is still an indispensable part of the current stage,and it is also a strategic choice for building a resource-saving and environment-friendly society.With the increasing traffic volume and the increasing axle load of vehicles,uneven cement concrete pavement seriously affects the ride comfort and comfort.The current study ignores the vibration relationship between the bus and the uneven cement concrete pavement,as well as the smoothness problems under different seat positions,different speeds,different pit depths,and different staggered heights.This shows that it is particularly urgent to develop the relationship between buses and uneven cement concrete pavement in public transportation.Based on the project of Zhengzhou Road and Bridge Co.,Ltd.in Henan Province,this article uses a common bus as the research object,combines the vehicle dynamics model with the cement concrete uneven pavement model,and analyzes the different seat positions,different speeds,and different road surfaces of the bus The mutual influence relationship among grade,different pit depth and different stagger height.Through the establishment of the bus dynamic model and the test simulation analysis,the research on the impact of uneven cement concrete pavement on the ride comfort of the bus was carried out,and the internal relationship between the uneven cement concrete pavement and the bus was revealed.The main research contents of the paper are as follows:(1)Based on the description of the virtual prototype research object and the theory of multi-rigid-body system dynamics,the dynamic equations of multi-rigid-body system dynamics are determined based on ADAMS software,and the initial conditions,static analysis and dynamics of the system model are carried out Mathematical analysis is given,and the summation flow of multi-rigid-body system dynamics solving method is given from the aspects of generalized coordinate selection,multi-body equation establishment and solution scheme.(2)Based on ADAMS/car,the basic structure of the bus model is elaborated,and the construction and simplification principles of the model parameters and the acquisition method of the bus performance parameters are described.Secondly,according to the requirements of the modeling rules,the key coordinate points of the suspension are determined,and the speed and damping force characteristic curves of the front and rear suspensions are analyzed.According to the topological structure of each subsystem,the three-dimensional model and dynamic model of the relevant subsystems of the vehicle’s front and rear suspension systems,steering subsystem,tire subsystem,body subsystem,powertrain subsystem,etc.were established respectively.Finally,the communication equipment is used to connect each subsystem model,and then the bus dynamic model of the bus is established.(3)The pavement environment of different grades of cement concrete pavement is analyzed,and the mathematical model of grade B and grade C random uneven cement concrete pavement is established.At the same time,according to the research content,the test point positions of the ride comfort test were determined,namely the driver’s seat position,the front left seat position,the middle left seat position,and the rear left seat position.The changes of the root mean square value of the three-way weighted acceleration on the X-axis,Y-axis,and Z-axis on the cement concrete pavement under different road grades,different speeds,and different seat positions are studied.The data was compared and analyzed,and the following conclusions were drawn:1)Under different levels of road conditions,the X axis,Y axis,Z axis,and the Z axis of the three directions have the largest acceleration changes;under different levels of road conditions,the rear passenger seat position is the most uncomfortable,and the middle passenger seat is relatively comfortable.2)Through comparative analysis,it can be found that on a good B-grade road surface,although the rms value of the total weighted acceleration differs between different locations,the rms value of the total weighted acceleration changes little with the increase of vehicle speed in different locations,respectively and the rms value of the total weighted acceleration between different positions of the C-level pavement with the increase of the vehicle speed,the change range becomes larger.Compared with the B-level road surface,as the vehicle speed increases,not only does the RMS value of the total weighted acceleration of different seat positions begin to increase,but also its comfort is lower than the B-level road surface.It can be found from this that the worse the road conditions,the greater the root-mean-square value of the total weighted acceleration at different locations as the vehicle speed increases,the larger the range of change,and the comfort becomes worse.(4)Two uneven cement concrete pavement model files of staggered pavement model and pits were established,different test locations for ride comfort tests were determined,and different staggered platform heights,different pit depths,different seat positions,and different The change of the absolute value of the maximum acceleration of the Z-axis at the driving speed combined with the evaluation method of the ride comfort of the passenger car draws the following conclusions:1)Staggered pavement and dimple pavement have a significant effect on vehicle ride comfort.The absolute value of Z-axis maximum acceleration is basically linearly related to the staggered height and dimple depth.2)When the stagger height is less than 10 mm and the pit depth is less than 20 mm,as the vehicle speed increases,the absolute value of the maximum acceleration of the Z axis at the four positions changes less,mainly due to the smaller stagger height and pit depth,The uneven height difference of uneven cement concrete pavement has little effect on the ride comfort of vehicles.It does not have a greater impact on ride comfort with the increase in vehicle speed and the difference in position.At the same time,it can also be seen that the vibration received by the rear seat position is much higher than the vibration received by the driver,the front left and right side seat positions,and the center left and right side seat positions.3)When the stagger height is constant,the increase in vehicle speed has little effect on the change in the absolute value of the Z-axis maximum acceleration of the seat position in the middle left.The main reason is the long distance between the front and rear axles of the bus,and the front and rear suspensions have vibration damping devices.When the front and rear wheels drive on the wrong road surface,the body vibration caused by the uneven road surface has the smallest impact on the position of the intermediate passenger,and then its The acceleration changes are stable.In this paper,the combination of theoretical research,modeling simulation and comparative analysis is used to complete the establishment of the bus dynamic model with the help of ADAMS simulation software.The interaction between buses and uneven roads at different positions,different speeds,different pit depths,and different staggered heights was analyzed and analyzed.Combined with the evaluation methods of buses and uneven roads,different locations,different road conditions,The changing rules of ride comfort at different speeds,different pit depths,and different staggered heights are important for revealing the changes in comfort between "people-buses" and the change in ride comfort of "buses-uneven roads". |
PDF Full Text Request