Research On Modal Characteristics Of Mechanical Elastic Wheels

The Mechanical Elastic Wheel(MEW)is a kind of non-pneumatic tire(NPT)that elastic structures are used to place the elasticity of pneumatic tires.On the basis of satisfying the performance of ordinary pneumatic tire,MEWs get rid of tire safety issues,such as broken,flat tire,and so on.Tire vibration and noise of tires have a direct effect on the driving smoothness,ride comfort and vehicle noise.It will be a very important tool for the tire designer to use finite element methods to study the modal characteristics of a tire,which will help to select the material of the tire,optimize the tire size more efficiently,and match the vehicle better.In addition,the impact of modal characteristics on the tires will also be the first step for automotive engineers to optimize suspension systems and wheels and reduce noise.The subject of this paper is to study modal characteristics and its influencing factors of MEW by finite element methods and LMS test equipment,on this basis,the modal analysis method is used to identify the damage of the wheel to provide some support for the health detection of the wheel structure.At the same time,the resonance frequency of the MEW under rolling condition is calculated,and the influence law of the rotating speed on the resonance frequency of the wheel is obtained.The modal characteristics of the MEW under rolling condition are obtained,which provides an important reference for the wheel structure optimization and vehicle matching.The main research contents are as follows:(1)The basic structure and working principle of MEW system was introduced in this paper,and the bearing type and bearing deformation of the wheel was analyzed.Next,the process of establishing finite element model of MEW was described emphatically.Finally,the static loading test was used to verify the accuracy of the finite element model,which lays the foundation for the subsequent simulation analysis.(2)The finite element model was used to analyze the static modal of the wheel,and the natural frequency and vibration mode of the wheel were calculated.The influence of material parameters(elastic modulus and density)of MEW on the wheel modal and the influence of structural parameters of MEW(wheel structure,arrangement of hinge group and length of hinge group)on the wheel mode were studied.At last,the orthogonal simulation method is used to determine which one of the variables contributes most to the first-order natural frequency of the wheel,so as to provide reference for further structural optimization of the mechanical characteristics of the wheel.(3)The basic theoretical knowledge of experimental modal analysis,namely the real modal theory,the whole process of modal test apparatus and equipment and MEW modal test was introduced in detail.Through the effective organization test,the influence law of bearing type,load,different exciting amplitude on tire modal parameters were studied,and the modal parameters of wheel under different test conditions were obtained.The accuracy of the model and the validity of the test are further verified by comparing the modal parameters of the MEW test with the simulation modal parameters(correlation analysis of modal frequencies and mode shapes).(4)The basic theory of damage was introduced,and then through the MEW fatigue simulation test and loading test to determine the location of the wheel danger zone.Then three kinds of methods introduce to identify the wheel damage based on the vibration characteristics,which were the frequency change,mode change and modal strain energy method.The results showed that the modal analysis can identify the damage of MEW structure,which provided some guidance for testing the health status of MEW.(5)The MEW under steady state rolling was taken as the research object,the influence law and mechanism of the rotational speed on the resonance frequency of the wheel were obtained considering the inertial force effect caused by rolling.In addition,under certain conditions,the key factors such as load,structure and material parameters affect the modal characteristics of the MEW under static state as well as the rolling wheel because the structure and material of the wheel hardly change.