The Development Of Simulated Program Of Independent Suspension Using The Natural Coordinates

Suspension is one of the important assemblies of modern vehicle,it connects the body and the wheels elastically. The main mission ofa suspension is to transfer forces and torques, and regulate therelative motion between the body and the wheels, at the same time abatethe impact from the road and damp the vibrations, so that the vehiclecould run smoothly. The design of vehicle suspension can directlyinfluence handling and stability, braking safety, ride comfort, andability to accelerate of the vehicle, it also influence the frictionand life span of the tires.Because of the importance of the suspension, there are manymodelling theories at present in the field of suspension modeling todiscover the kinematic and dynamic characteristic of suspension. As aresult of the complexity of suspension, the multibody system dynamicsmethod is the most popular one, it is object-oriented and can analysisand compare the characteristics of all sorts of components, and can beparameterized easily.There are two mainly phases of the application of multibody systemdynamics method to suspension analysis.In the early literature,thekinematic analysis was corcerned. Recent years, the dynamic performancethat consideration the rubber bushing of the suspension was concerned.Most of them were using the Cartesian method.Using natural coordinates method to analysis the kinematic anddynamic performance of mechanical systems have many advantages, suchas the simplicity of modeling , the advantage of computer program andthe important advantage in computational efficiency.In this paper, we take the advantage of natural coordinates methodto develop a computer program to simulate the behavior of independentsuspension systems. The program was developed according to theprinciple of Object-Oriented programming. The program can establish thedynamic equations of suspension systems in a computer-oriented andsystematical way, and can solve the equations automatically. Theprogram is easily to use, and has the advantages of accurateness,genelization and the rapidness of simulate.Through this work, we have found a simple and fast way to simulatethe behavior of the independent suspension, and accumulate experiencein using multibody method to develop suspension simulated program(especially the object-oriented procedure development).The main work in this dissertation include:① After comparing the most popular types of coordinates currentlyused in multibody system dynamics, then we choose the naturalcoordinates method to develop the suspension simulated program.② Elaborate on how to use natural coordinates to define the motionof mechanical systems, including the basic point, the kinematicconstraint equations.③ Elaborate on how to carry on the kinematic analysis in detail.Including position analysis, velocity analysis, acceleration analysis.④ Elaborate on how to carry on the dynamic analysis in detail.Including mass matrix and force vector of mechanical systems,formulation of the equations of motion, numerical integration andsolution of the resulting equations.⑤ Develop the simulated program using the concept ofObject-Oriented programming, so it is easy to program, maintain andextend.⑥ Develop the algorithm to make the program formulate and solvethe equations of motion automatically.⑦ Develop the mathematical model and functions about the wheelalignment of suspension, such as camber angle, toe angle, steeing axisinclination, castor angle and half track change.⑧ Using the program to simulate a multi_link suspension, which wasproposed by the European automobile industry as a benchmark problem tocheck multibody dynamic codes. Compare the result of the program andthe result of the ADAMS.⑨ Using the program to simulate a double wishbonesuspension,including the kinematic problem, dynamic problem. Comparethe result of the program and the result of the ADAMS.