| With the continuous improvement of people’s living standards,the functions of motorcycles have gradually changed from early mobility tools to entertainment tools.Large displacement(>250m L)motorcycles with strong power and excellent handling performance have been favored by the market in recent years.Due to insufficient attention in early research and development of domestic large-displacement motorcycles,their performance,especially the dynamic performance of suspension systems at high and medium speeds,is significantly different from similar products in developed countries.Therefore,in order to improve the competitiveness of China’s large-displacement motorcycles,it is necessary to conduct research on the dynamics of large-displacement motorcycle suspension systems.Taking a domestic 500m L large-displacement motorcycle as the research object,aiming at the problem of wobble and weaving of the suspension system during high-speed driving,a motorcycle dynamic model was established for simulation analysis.Sensitivity analysis,approximation Modeling and multi-objective optimization methods are used to complete the optimization analysis of the suspension system parameters,and the root trajectory theory is introduced to verify the optimization results.The main research contents and conclusions are as follows:(1)Based on domestic and foreign research,the Lagrange method is used to derive the equation of motion of the motorcycle,the motorcycle model is established,and the dynamic simulation analysis is completed.The simulation phenomenon is basically consistent with the problem of motorcycle wobble.(2)Aiming at the wobble problem of the motorcycle,establish a mathematical model of the optimization problem,compare and analyze the characteristics of each optimization algorithm,and select the NSGA-II algorithm to complete the optimization analysis of the front suspension system.The yaw rate and lateral acceleration extremes of the center of mass position of the front wheel after optimization were changed from 323.2deg/s and3.1g(30.4m/s~2)before optimization to 0.1deg/s and 0.11g(1.1m/s~2)after optimization respectively,the vibration problem of the motorcycle has been significantly improved.(3)Comprehensively consider the problems of wobble and weave,and perform sensitivity analysis on the parameters of the motorcycle suspension system to identify key parameters.The response surface method,radial basis neural network method,and Kriging method are used to complete the approximate modeling.The error analysis determines that the response surface approximate model has the highest accuracy.Based on the sensitivity analysis and response surface approximation model,the NSGA-II algorithm was selected to complete the multi-objective optimization of the suspension system parameters.After optimization,the peak angular velocity and yaw rate of the center of mass of the entire vehicle changed from 14.59deg/s and 14.33deg/s before optimization to 0.31deg/s and 0.43deg/s after optimization,respectively.The peak value was changed from 2.1g(20.58m/s~2)before optimization to 0.95g(9.31m/s~2)after optimization,and the motorcycle wobble and weave problems were solved.(4)Compare and optimize the performance indicators of the motorcycle before and after optimization,and use the root trajectory theory to compare and analyze the stability of the motorcycle before and after optimization.The results show that the modal stability of the motorcycle after optimization is better than that before optimization,and both are in the stable region.The feasibility and effectiveness of the optimization scheme are verified.Through optimization analysis of the parameters of the large-displacement motorcycle suspension system,the problems of the suspension system’s wobble and circuitous swing during high-speed driving are solved,and the vehicle’s driving stability is significantly improved.The research content provides reference for the design and development of large-displacement motorcycles in China,and has high engineering application value. |
PDF Full Text Request