Simulation And Multi-objective Optimization Of Ride Comfort And Road-friendliness Of Six-axle Tractor Semi-trailer

In the "Internet plus" era,the logistics and transport have been developed rapidly,but our country still need to continue improving in the construction of integrated transportation system.As an effective way to improve logistics efficiency and reduce logistics cost,multimodal transportation is an important part of the comprehensive transportation system.Highway transportation needs to be connected with other modes of transportation,so tractor semi-trailer can take full advantage of centralized and efficient transportation.In long-distance transportation process,the six-axle tractor semi-trailer is the typical model of tractor semi-trailer,the vibration and the impact to the vehicle influences the ride comfort of the tractor semi-trailer owing to the road surface excitation,and the consequent wheel dynamic load fluctuation will also damage the road.Therefore,it is necessary to study the ride comfort and road friendliness of six-axle tractor semi-trailer.In current,the research on the ride comfort and road-friendliness of six-axle tractor semi-trailer has been carried out,but there are still some deficiencies,the simplified vibration model doesn't fully reflect the structural characteristics in the actual application to improve ride comfort and road friendliness.There are few comprehensive study on the road-friendliness of the six-axle tractor semi-trailer,and there is little contrast analysis and study of the multi-objective optimization scheme of six-axle tractor semi-trailer.In this paper,considering the structure characteristics,the six-axle tractor semi-trailer simplified vibration model is established.The statistical characteristics of the vibration response of ride comfort,the derivation and calculation process of the road-friendliness evaluation indexes are studied.The influence of different parameters on ride comfort and road-friendliness is analyzed.Through the sensitivity analysis,multi-objective optimization of ride comfort and road-friendliness of six-axle tractor semi-trailer is implemented.The different optimization schemes are analyzed and compared,which has important guiding significance for the matching and improvement of six-axle tractor semi-trailer.The specific contents are as follows(1)According to the corresponding simplified assumptions,the main components can reflect the vibration performances of six-axle tractor semi-trailer are retained,and the plane vibration mechanical model is established.Through the Lagrange equation and the equation of equilibrium,the matrix expression form of vibration mathematical model and the static load of the main bearing part are obtained.Based on the statistical characteristics of the front wheel road excitation,the frequency response functions of the main acceleration and the main bearing components relative dynamic load and dynamic deflection,and the statistical characteristics of the vibration responses are obtained.The frequency characteristics and velocity characteristics of the vibration responses under different vehicle speeds and different pavement level characteristics are analyzed.The influence of parameters combination of tractor and semi-trailer on ride comfort evaluation index is studied.(2)The four commonly used road friendliness evaluation indexes are summarized.Based on the expression form of the corresponding evaluation indexes,the theory road damage coefficient is deduced from the frequency domain.The simulation algorithms of four kinds of road friendliness evaluation indexes based on the simplified plane vibration model of the six-axle tractor semi-trailer are presented and the simulation program is developed.The velocity characteristics of road friendliness of six-axle tractor semi-trailer under different pavement level characteristics are analyzed.Road damage coefficient and theory road damage coefficient which can describe the whole vehicle's damage to the pavement are selected to be the main road-friendliness evaluation indexes of six-axle tractor semi-trailer.The influence of the parameters combination of tractor and semi-trailer suspension on road-friendliness is studied.(3)Based on the multidisciplinary optimization software platform Isight,the parameter sensitivity analysis of ride comfort and road friendliness of six-axle tractor semi-trailer is implemented through the method of optimal Latin hypercube design,and the major influential factors are obtained.Combined with the actual situation,the suitable parameters are selected,and the multi-objective optimization of the ride comfort and road friendliness is carried out by using the neighborhood cultivation genetic algorithm.According to the corresponding rules,different optimization schemes are selected,and the optimized results are compared and analyzed.The bar chart and radar chart are used to analyze the changes of each evaluation index under different optimization schemes to weigh the option.The results show that,under the selected optimization,the evaluation indexes of ride comfort and road friendliness can also be optimized in the range of common driving speed.