Hydraulic Modular Assembled Semi-trailer Steering System Simulation And Optimal Design

Firstly, the research background of steering system of hydraulic modular assembled semi-trailer is introduced in this thesis. Combining with the development trend of assembled trailer and the enterprise's actual requirements, the necessity and urgency as well as the main purpose and significances of the research are discussed. In a detailed analysis of study statuses of vehicle steering mechanism at home and abroad, the principal contents of this thesis are put forward.Then, the overall structure and main technical characteristics of hydraulic modular assembled trailer are analyzed. The splicing forms are introduced. The structure characteristics of steering system, steering realizing ways, the structure of centerplate and steering board as well as linkages' layouts change rules of different splicing forms are presented.Afterwards, starting from Ackermann principle the theoretical steering characteristics of multi-axis and all-wheel steering vehicles are analyzed. The theoretical steering angle formulas of assembled semi-trailer, whose basic splicing unit is 6-axle module, are derived. The matrix transform algorithm, which can be used to calculate the practical wheel angle of a variety of splicing forms when all-wheel steering is done, is put forward, and by using this algorithm each wheel's practical angle formula of 6-axle module is derived. Based on the above work the general optimal design mathematical model of steering mechanism of assembled semi-trailer is given.On the basis of analyzing structural characteristics of steering mechanism, model simplification and parametric modeling are studied. Taking into account the workload, calculation scale and computing time, by use of ADAMS parametric modeling approach four typical splicing forms' parametric models are established under reasonable simplification. Through simulation the differences between actual wheel angles and theoretical angles are achieved.The general objective function expression of steering mechanism optimal design is proposed. The optimal design mathematical models of steering mechanism of four typical splicing forms are built. Using the method of variables reduction and equality constraints elimination, which combining global coordinate and local coordinate, connecting points of four steering mechanisms are respectively optimized. Through optimization, the target of single-module form falls 38.4%, double-module form drops 22.8%, three-module form drops 18.2%, and four-module drops 23.2%, steering performance is obviously improved. On this basis in order to improve design efficiency and provide convenient and practical design tools to company's designers, the optimum design module by using ADAMS secondary development is designed and achieved.Finally, the user-oriented query module for splicing forms of assembled trailer is designed, and is realized in the Dreamweaver Platform. By use of this module querying the layout of the steering linkage in single-module form is done.All of the studies offer a reference to the research of steering system of assembled trailer, solves the enterprise's practical problems, provide practical tool for optimization of steering mechanism as well as new idea and possible ways for steering system research of assembled trailer, and have a fine practical significance.