| The precision equipment semi-trailer train is a kind of semi-tractor which is mainly designed for transportation of precision equipments.Because vibration resistance of precision equipments is generally weak, which are often easily damaged due to vibration of the vehicle,so the ride comfort about transport of goods need to be emphasized in the design process of such semi-trailer.This paper discusses the present research situation in vehicle ride comfort,gets a conclusion that there is few research in ride comfort of goods,especially that it has not reported any research on ride comfort of the driver and goods about precision equipment semi-trailer. Then both of the significance and purposes of research about precision equipment semi-trailer is elaborated,in addition, the technical route is advanced.Subsequently, the theories and evaluation criteria about ride comfort are discussed,and the overall scheme of precision equipment semi-trailer with flexible traction device is presented. According to structural features of the semi-trailer,research about vehicle dynamics model is advanced.Through reasonable simplification, theoretical 18 DOF vehicle dynamics model and virtual prototype parametric model of vehicle are created.Based on the theoretical analysis of the dynamic model, modal formulas of vehicle vibration system about precision equipment semi-trailer is obtained,then use the modal formulas to calculate natural frequencies and the vibration model of a typical precision equipment semi-trailer. Comparing the calculated results and simulation results which are obtained by Adams, the modal formulas are proved right.Combined with the characteristics of the vehicle vibration system, this paper analyzes the response formulas of precision equipment semi-trailer under random road excitation,then extended the 18 DOF parametric model to 23 DOF parametric model.On basis of the 23 DOF parametric model, modal simulation and vibration response simulation about a typical precision equipment semi-trailer are carried out, then the frequency response curve of the vehicle vibration system is received, acceleration PSD curve of some points is obtained,which including barycenter of goods, cushion etc.Combined with the evaluation method, use the filter function generators to weighting network filtering the acceleration of vibration points. According to the results, this paper evaluates the ride comfort of the precision equipment semi-trailer and analyzes the impact on ride comfort of the precision equipment semi-trailer affected by speed, road grade,simplification of DOF.According to the requirements of enterprises about ride comfort, the optimization design mathematic model of vehicle suspension system is built,which is including tractor primary suspension system, cab suspension system, trailer balanced suspension system, flexible traction device. Making the acceleration PSD of barycenter of goods be minimum, making the acceleration PSD of barycenter of goods be minimum, two optimization results are obtained respectively.Subsequently, in order to eliminate the anomaly crest, this paper adjusts the optimization results to get two improvement project.Finally, improvement project ? is chosen as the final parameter project of suspension system of the precision equipment semi-trailer.All studies in this paper not only provide design engineers ideas and references to design the suspension system of precision equipment semi-trailer,but also solve the actual problems for enterprises,meanwhile,the vehicle vibration modal formulas can provide the theoretical reference for independent design of suspension system in similar vehicles. |
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