Vibration And Fatigue Analysis Of Motorcycle Based On Virtual Prototype Technology

With the development of science and technology and the diversification of social life,the diversification of people’s travel tools has become an inevitable trend.Motorcycle,as an electromechanical product integrating transportation and entertainment,is an inevitable choice of people’s transportation diversification.Therefore,it is still of great practical significance and engineering value to study the vibration comfort and fatigue reliability of motorcycle when studying its entertainment function.In this paper,according to the requirements of a new motorcycle developed by an enterprise,the vibration response of handlebars,seats,pedals and other key positions and the vibration fatigue of the frame of the main structural parts during the engine and road excitation are studied with virtual prototyping technology,so as to predict the vibration response and fatigue life of the new motorcycle.The main contents and conclusions of the thesis are as follows:Firstly,the finite element model of motorcycle frame is established by using virtual prototyping technology,and its structure calculation mode is analyzed.The model synthesis method is used to extract the neutral files of the frame,and the parameters,relative constraints and motion relations of each component.A virtual test was carried out on the motorcycle under the normal speed of 50km/h.Compared with the bench test results of real cars,it is found that the vibration peak frequencies of measuring points such as seats,handlebars and pedals are basically the same,and the vibration simulation amplitude of some frequencies is slightly different from that of real cars.The vibration amplitude of the seat,handlebar and other measuring points is larger at 91.5Hz,137Hz and 183Hz,which is close to the modal first-order frequency of 94.53Hz and fifth-order frequency of 182.84Hz of the frame and produces resonance,thus affecting the riding comfort and the structural fatigue life of the motorcycle.According to the study on the driving comfort of the vehicle’s common speed,the vibration weighted acceleration value after the mass vibration absorber is designed at the handgrip is 4.84m/s²,which is significantly improved compared with that before the improvement,indicating that the driving comfort of the vehicle basically meets the requirements.Secondly,on the virtual prototype model,load standard QCT₈19-2009"the two rounds of motorcycle and two rounds of portable motorcycle frame,horizontal,vertical and occupant load three conditions,application of Miner linear cumulative damage theory,considering the motorcycle frame structure characteristics,material fatigue properties,and so on,with the static fatigue life of motorcycle virtual test.The fatigue simulation results show that the cycle times are 100,500 times,198,000 times and 337,000 times respectively in the horizontal condition,vertical condition and occupant condition.According to the national standard,the fatigue test of the frame was stopped and inspected after 100,000,150,000 and 230,000 endurance tests respectively in the horizontal condition,vertical condition and occupant condition,and no fatigue damage was found.The fatigue life of the three working conditions all meet the engineering requirements.The feasibility of the static fatigue life simulation method is verified by the comparative analysis of static fatigue simulation,test and fatigue test standards.Finally,considering the fatigue problem is actually motorcycle vibration fatigue,so according to motorcycle virtual prototype has been established,considering the influence of the random vibration of structural damage,by the method of frequency domain,the motorcycle vibration fatigue virtual experiment was carried out,to get the motorcycle each measuring point frequency response function,surface excitation power spectral density of motor and load,speed of 50 km/h,which are used in motorcycle in condition of virtual vibration fatigue tests are carried out.The results show that the vibration fatigue life of the motorcycle can reach 275,000 km under various random loads of the engine and road surface under the uniform speed of 50km/h.In this paper,the vibration comfort and fatigue reliability of motorcycles are studied from the aspects of theory,calculation and experiment.In the past,when scholars studied the durability of motorcycles,they only studied the static fatigue of motorcycle frames,but ignored the vibration fatigue caused by random vibration of motorcycles.This paper studies the vibration fatigue of motorcycle and provides a new method for reliability assessment and frame fatigue optimization design of motorcycle.