Vehicle Vibration Model Includes The Non-linearity Of Leaf-springs

With the rapid economic development, the transportation between different places become more and more prosperity in our country. In order to improve the efficiency and reduce the cost, the trucks become faster and load heavier. The vibration and noise make drivers tired on the trips, thus leading to the traffic danger. Moreover, large proportion of goods damage in transit results from excessive vibration. Therefore, all the manufacturers try their best to make their trucks more comfortable and quiet. There are various methods to achieve this goal, among which establishing a vibration model to predict the behavior of the vehicle and optimize the factors that affect the vehicle?s ride and Noise, Vibration, Harshness(NVH) performance is one of the best methods in the early period of the design process.At present, there are three kinds of vibration model for trucks: Finite Element Model(FEM), Multi-body Dynamics Model and Numerical Model. The FEM is not suitable for long history calculation. When establishing Multi-body Dynamics Models, researchers take a little of nonlinear factors into account. It leads to a poor accuracy. Based on the reasons above, in this paper, by regarding a truck as the re search object, two numerical vibration models of the vehicle are established, Finally the accuracy of the model is validated through experiments in this paper.This paper includes the following contents:1) Leaf springs are key components of heavy trucks, their mechanical properties have an important influence on the vehicles? ride and NVH performance. Taking the leaf springs of the truck as experimental subjects, a series of static and dynamic tests are carried out, and the experimental data is analyzed wi th commercial software Matlab, then the dynamic characteristics of the leaf springs are acquired.2) The amplitude-frequency and mechanical characteristics of Fancher model, Rate-dependent Triboelastic model, Leaf springs? General model and Maxwell-slip model are analyzed. Furthermore, the parameters are identified from the experimental data. Maxwell-slip model is simple and easy to be improved, so a new model is established based on it, then the accuracy and the transient property of the new model is validated with the test data.3) Road roughness is very important for vehicle dynamic simulation. The time domain model of road roughness of different tires is established according to Power Founction and take the time-space correlation into account. The accuracy of the model is validated with standard data.4) A model of 3-dof and a model of 4-dof tandem suspension is established, and their response under road roughness is compared with each other. A model of tandem suspension that contains leaf springs? dynamics model is established and compared to the two tandem suspension models that mentioned above, validating the rationality of the new model.5) Two types of models--one contains rigid-flexible coupling and the nonlinearity of leaf springs and tandem suspension,the other does not--are established based on the structure of the vehicle according to D ’Alembert principle. The dynamic equations of the models under road roughness are solved, and the response is compared with each other. Finally, the drops and pulse excitation of the vehicle is simulated through the two models, the results are compared to the test data, validating that it?s necessary to take the nonlinearity of leaf springs into account when establishing a whole truck model.