Dynamic Modeling And Rigid-liquid Coupling Characteristics Of Heavy-duty Vehicles With Storage Tanks

With the rapid development of China's economy,the domestic demand for heavy vehicles with liquid-filled tank is increasing rapidly.Under the operating mode of turning or emergency avoidance,violent liquid sloshing will produced in the tank,and the vehicle handling stability and lateral driving stability will significantly affected by the corresponding unbalanced sloshing force and moment.Moreover,complex rigid-liquid coupling dynamics will be aroused between the liquid sloshing and the motion of vehicle suspension system.As it will increase the undesirable probability motion of the vehicle's roll and rollover,so a major hidden trouble of the road traffic safety could be caused.In the present paper,the heavy vehicle with liquid-filled tank was mainly studied,and the sloshing damping and the liquid-solid coupling effect between the liquid and the anti-sloshing plate are considered,and the practical equivalent mechanical model of liquid sloshing of tank are improved systematically by using the methods of theoretical analysis,finite element simulation and numerical simulation.With tank class roll of heavy vehicle dynamics model,by using Lagrange equation,the corresponding kinetic equation of state are derived.Through mountains of numerical simulation,the vehicle coupling system dynamic characteristics are studied deeply.Moreover,the roll stability performance and conditions of the vehicle are assessed in detail.Among them,the main specific work is as follows:(1)Based on the theory of fluid dynamics,the formulae for calculating the dynamic characteristics of liquid sloshing damping,sloshing force and sloshing moment of tank are given,and the parameter identification method and fitting condition of the equivalent mechanical model are established by using the convolution formula and Fourier transform.(2)Considering the actual working conditions of the tank truck in the operating mode of turning or emergency avoidance,the corresponding numerical simulation model is established with commercial finite element software.The natural mode and natural period of liquid sloshing of tank with different liquid filling ratios were studied respectively by modal analysis without anti-sloshing plate or with different anti-sloshing plates.The sloshing suppression effect of dissimilar anti-sloshing plate was studied by loading different external excitations and initial conditions.Taking the shaking force and shaking moment as the target performance parameters,the anti-sloshing plate in the tank is selected and evaluated,which provides some reference for practical engineering design.(3)The sloshing law of the liquid of tank without damping was described by establishing the liquid sloshing equivalent single pendulum model,which overcomes the limitation of the traditional equivalent mechanical model.According to the convolution formula under the external excitation of the step,the time-domain expression of the shaking force and torque acting on the tank by the equivalent single pendulum is derived.The equivalent values of sloshing mass,sloshing center,sloshing length and sloshing damping ratio were obtained by spline parameter fitting,and the corresponding parameterized equivalent mechanical model was improved.The accuracy,practicality and generality of the equivalent parameters are verified by calculation examples under different working conditions.(4)Based on the fitting parameterized equivalent mechanical model,the roll dynamics model of heavy vehicles with storage tanks is further established.Study the effect of different lateral acceleration on the roll stability,the results show that,The coupling effect between the moving state of the tank truck and liquid sloshing makes the liquid sloshing oscillation period longer,and with the increase of lateral acceleration,the amplitude of load transfer rate of the tank truck will increase accordingly,thus reducing the stability of the vehicle.In addition,the stiffness difference between the vehicle's left and right wheel damping and spring has a great impact on the stability of the roll.The roll stability of the tank truck will be sharply reduced when the damping and stiffness difference between the left and right wheels is too large.Therefore,the performance of the suspension system should be checked regularly to ensure the stability of the vehicle.