Dynamics Of Multibody Systems With Unilateral Constraint

With the development of dynamics of the multibody systems the problem of unilateral constraint has been paid more attention by people.Beause the rope has been used in many fields such as the ship,the aerospace and so on,the unilateral constraint problem caused by the rope has become more and more important.When the traditional method is used to solve the problem of unilateral constraint, frequent judgment of the unilateral constraint contact conditions will cause a lot of difficulties and it is impossible for analysis and modeling.So it is very improtant to find simple models for analysis and modeling.Using simple modeling methods to analyz the unilateral constraint problem and the complex rigid-flexible coupling multibody system which the rope is the flexible body is proposed to find in this thesis.The main research work can be summarized as follows:(1)The multi-rigid body dynamic model can efficiently deal with a strongly nonlinear problem.Discrete model of the rope is established by using multi-rigid body sphericla hinge model.So the problem of unilateral constraint will be changed into a bilateral constraint problem.Use the software of the multibody and ADAMS to model and analyz.(2)Compared with the finite element method used in the flexible multibody system,the finite segment method has an unparalleled advantage,if the elastic deformation of the rope should not be neglected in the complex rigid-flexible coupling multibody system.The finite segment method has been used to make the complex rigid-flexible coupling system become to be a multi-rigid-body dynamics problem which is a more mature system in this thesis. Dynamic equations will be built on the above coordinate system,rather than the flexible body coordinate system.The overall deformation of the non-deformation will be descriped by inter-segment linear deformation.This will not only make the problem greatly simplified,but also make the accuracy futher improved.(3)In the end pendulum system,drag-and-drop system and collision system are exampled for modeling and analysis using the former mentioned modeling methods with MATLAB in the multibody systems programs and ADAMS in this paper.The numerical simulation proves the validity of the modeling methods.