New Exploration And Application Of Theoretical Analysis Modeling And Simulation Method Of Three Axle Heavy Vehicle Ride Comfort

With the development of the world's economy, rapid increase of commodity circulation, and wide spread of the highways, heavy vehicle has gradually become the primary means of highway transportation. In addition, with technology progress in automotive industry, improvements in living standards and increases in the average vehicle speed, the requirements for ride comfort of heavy vehicle have increased. Therefore, ride comfort has become a main indicator for characterizing performance of heavy vehicles.Heavy vehicle generally has long body, big wheelbase and large bearing quality, the body bending vibration due to the body's elasticity is significantly pronounced and has become an important factor in heavy vehicle ride comfort. Therefore, it is necessary to consider the body's elasticity in the analysis of the ride comfort of heavy vehicle. In this paper, the theoretical analysis modeling and simulation method research of the three axle heavy vehicle ride comfort are paid attention to. Subsequently, the new exploration and application of theoretical analysis modeling and simulation method for the three axle heavy vehicle ride comfort is conducted and the planar rigid-elastic synthetic model and spatial rigid-elastic synthetic model for the three axle heavy vehicle are established. The comparison between the traditional method and the pseudo excitation method is carried out after the above two methods are constructed. The investigation for the analysis of influence factor and multi-objective optimization design is carried out based on the concept of the Isight and Matlab co-simulation. The main contents in this paper are depicted as follows:(1) Theory analysis of a uniform beam with both ends free based on the rigid-elastic synthesisAccording to the basic equations of bending vibration of an elastic beam, the basic equations and inherent characteristics of a uniform elastic beam with both ends free are derived, and the orthogonality of the inherent mode shape function is justified. The motion synthesis between the rigid motion and bending vibration of the beam is implemented, and subsequently the energy analysis is conducted. Subsequently, the mass matrix, stiffness matrix, kinetic energy and potential energy are derived after the motion synthesis of a uniform beam with both ends free is obtained. In theory, the bending vibration of an elastic beam is generalized to the bending vibration of the rigid-elastic synthesis.(2) Establishment of planar rigid-elastic synthetic model of three axle heavy vehicle In order to consider the bending vibration of the heavy vehicle body, the body is regarded as a uniform beam with both ends free, and then the mechanical and mathematical planar rigid-elastic synthetic model with 10 degrees of freedom of the three axle heavy vehicle are established. Finally, the formulas of the wheel static load and the vibration response of the three axle heavy vehicle are derived.(3) Theory analysis of a rectangular thin plate with four sides free based on the rigid-elastic synthesisAccording to the differential equations and variation equations of the transverse vibration of the thin plate, the free vibration equations of the thin plate are derived. The natural frequency and mode shape of the rectangular thin plate with four sides free are solved analytically using the single beam function method and the results are validated by the finite element method, and subsequently the orthogonality of the mode shape is verified. The motion synthesis between the rigid motion and elastic bending vibration of the thin plate is implemented, and then the energy analysis is conducted. The mass matrix, stiffness matrix, kinetic energy and potential energy are derived after the motion synthesis of a rectangular thin plate with four ends free is completed. In theory, the transverse vibration analysis of a thin plate is generalized to the vibration analysis of the rigid-elastic motion synthesis.(4) Establishment of spatial rigid-elastic synthetic model of three axle heavy vehicleFor the sake of the bending vibration of the heavy vehicle body, the body is assumed to be a rectangular thin plate with four edges free, and sebsequently the mechanical and mathematical spatial rigid-elastic synthetic model with 17 degrees of freedom of the three axle heavy vehicle are built. Finally, the wheel static load and the vibration responses of the three axle heavy vehicle are deduced. It provides a new approach for building the spatial model of heavy vehicle with respect to the body rigidity and elasticity.(5) Simulation and analysis of the ride comfort of three axle heavy vehicle based on the rigid-elastic synthesisThe traditional method and the pseudo excitation method for the simulation of the three axle heavy vehicle ride comfort are constructed and subsequently the comparisons between the above two methods is conducted based on the planar and spatial rigid model and rigid-elastic synthetic model. The simulation results between the rigid-elastic synthetic and rigid modelare compared. Altering the elasticity variables, it can realize the transformation from the rigid-elastic synthetic model to the rigid model. Aiming at the planar rigid-elastic synthetic model of the three axle heavy vehicle, the main factors which affect the ride comfort of the three axle heavy vehicle are found out by using the sensitivity analysis based on the Isight and Matlab co-simulation and subsequently the multi-objective optimization design is conducted to improve the heavy vehicle ride comfort.The innovation in this paper is given as follows:(1) On the basis of the previous works, the concept of rigid-elastic synthesis is put forward and the explanation of rigid-elastic coupling is given. According to the bending vibration theory of the elastic beam, the theory on a uniform elastic beam with both ends free is further studied. Based on the motion synthesis of rigid motion and elastic bending vibration, the bending vibration theory is generalized to the rigid-elastic synthetic theory, overcoming the problem of too simple description in the previous works. Based on the assumption that the body is regarded as a uniform elastic beam with both ends free and the primary components considered in the three axle heavy vehicle, the planar rigid-elastic synthetic model with 10 degrees of freedom for the three axle heavy is established, which features less parameters and convenience for the practical engineering application.(2) Aiming at the problem of the establishment of only planar rigid-elastic synthesis model at home and abroad, the natural frequency description of free vibration thin plate is given based on the derivative equations and variation equations with respect to the bending vibration theory on the thin plate and the corresponding vibration relationship between the planar elastic beam and spatial thin plate. The natural frequency of rectangular thin plate with four sides free is derived and the beam function of rectangular thin plate with four sides free is given, based on the single beam function method. According to the synthesis motion of rigid motion and transverse elastic vibration, the transverse elastic vibration theory of the thin plate is generalized to the rigid-elastic synthesis theory. The body is regarded as a rectangular thin plate with four ends free and 17 degrees of freedom spatial rigid-elastic synthetic model of the three axle heavy vehicle is built by the thin plate theory. It provides a new modeling approach for building the spatial rigid-elastic synthetic model for the multi-axle heavy vehicle.(3) The traditional method and the pseudo excitation method for the three axle heavy vehicle are constructed, which are appropriate for either the rigid-elastic synthetic model or the rigid model. Compared with the traditional method, the pseudo excitation method is not necessary to derive the frequency response characteristic of the vibration response. Furthermore, the derivation and solution of the equations are simpler. According to the planar and the spatial rigid-elastic synthetic model and planar and spatial rigid model, the simulations are conducted. The results indicate that the pseudo excitation method is identical to the traditional method. Altering the elastic parameters of the rigid-elastic synthetic method, the transformation from the rigid-elastic synthesis to the rigid model is realized.(4) Aiming at the rigid-elastic synthetic model of the three axle heavy vehicle, the sensitivity analysis is implemented by using the optimal Latin hypercube design method, based on the Isight and Matlab co-simulation. As a result, the main factors which affect the ride comfort of the three axle heavy vehicle are found out. The multi-objective optimization design of the three axle heavy vehicle is carried out by using the archived-based micro genetic algorithm, which provides some theory basis and technical means to improve the heavy vehicle ride comfort.