The Lateral Dynamics Modeling And Parameter Optimization Matching Of The Semi-trailer Tanker

Tractor semi-trailer tank vehicle(TSTTV)is the primary road transportation vehicle for fluid cargoes such as petroleum and chemical products,and it plays a vitally important part in the fluid cargo transportation of short and medium distance.However,when the significant economic benefits are brought by tank vehicles at the same time,tank vehicles are often rollover and sideslip to generate instability,causing serious traffic accidents.In order to facilitate the optimal design of the TSTTV to comprehensively improve the roll stability,yaw dynamics and the vehicle handling property,also to consider a fact that the study on the TSTTV was mostly limited to tank itself around the world,a coupling lateral dynamics model for the TSTTV has been established in this paper based on the Lagrange approach and trammel pendulum equivalent mechanical model which simulating the fluid slosh,and a general optimized matching method of tank-vehicle parameters for the TSTTV is proposed.First of all,improvements of trammel pendulum equivalent mechanical fluid sloshing model.To refit model parameters through CFD model under the fluid nonlinear sloshing condition by applying the active excitation.According to the sum of the squared residuals,the coefficient of determination,the correction coefficient and the root mean square error in the process prove the refitting accuracy is high,then the fluid sloshing moment response of the trammel pendulum model,improved model and CFD model are compared under the same conditions.The results show that improved model has good goodness of fit with CFD model,which can make up for the lack in high fill level condition compared with the original model,so it has greater applicability and accuracy.Then,this paper focus on the establishment of coupling lateral dynamics model for the TSTTV based on the Lagrange method and improved trammel pendulum equivalent mechanical fluid sloshing model.As a distinct feature,this model appropriately integrates the motion degrees of freedom those are vehicle yaw motion,body side slip,roll motion of the sprung mass,nonlinear lateral tire force and fluid sloshing dynamics into one model.Thus,this model bridges the relationship between the fluid sloshing dynamics and the vehicle lateral dynamics.The proposed model is evaluated by open-loop response and subject to sine with dwell steer input and step input.Yaw velocity of tractor,slip angle,roll angle,fluid sloshing angle and load transfer ratio under two fill level cases(FL=40%,FL=80%),three tank ellipticity cases(?=1.0,?=1.2,?=1.4)and three wheel bases of semi-trailer(L=5.5m,L=6.0m,L=6.5m)are evaluated in the simulations.The results reveal that the proposed model can well reflect the effects of fill level,tank geometric parameters,wheel base of semi-trailer and other transportation conditions on the vehicle roll stability,planar yaw dynamics and the vehicle handling property,so it is rather suitable to be used for the study of the lateral coupling dynamics of the TSTTV.Especially,this model can be used to study the design requirements of the TSTTV subject to some certain transportation conditions such as the fluid type,fill level and road feature aiming to comprehensively improve the vehicle handling stability.So,it is of great significance to enhance the design performance of the tank vehicle to improve the driving safety.Finally,three objective evaluation indexes of handling stability are selected,and the six parameters matching with vehicle are determined from twelve important parameters of the TSTTV by test of sine with dwell steer.According to the design of orthogonal text,adopting the optimal combination of parameters and the numbers of texts,multivariate linear regression equations of objective evaluation indexes and vehicle structure parameters are obtained at low fill level FL=40% and high fill level FL=80%.At the same time,the comprehensive objective evaluation indexes of the TSTTV handling stability are determined according to the weight in the actual transportation process of each fill level,those are rollover stability and yaw stability comprehensive evaluation indexes.Then the multi-objective linear programming problem is solved by the linear weighted sum method.Two comprehensive objective evaluation indexes are used as objective functions to optimize the matching parameters,and the optimized simulation results are compared.The results show that the vehicle handling stability has been greatly improved after optimized matching of the TSTTV parameters.