Research On Design And Dynamic Performance Of A Novel Three Configuration Metamorphic Mechanism

In recent years,the metamorphic mechanism has developed into a new research direction in institutional science,because it can restructure itself in different working environment and different functional requirements in order to realize the deformation of the spatial structure of the mechanism,and then the metamorphic mechanism attracts the attention of many researchers.In this paper,a novel three configuration metamorphic mechanism which can be flexibly transformed between three degrees of freedom,two degrees of freedom and single degree of freedom is taken as the object of study.Firstly,based on the graph theory,three activity-ten linkage mechanism is synthesized,Through screening the configurations,we selected one of them as the original configuration,a novel three configuration metamorphic mechanism is designed through increasing and decreasing the bars and the absence of kinematic pairs.The degree of freedom of the metamorphic mechanism is calculated by using the screw method,and through the scale synthesis of the metamorphic mechanism,the constraint relation between the bars of the mechanism system is analyzed out,and then,the metamorphic mechanism is established.Later,the closed loop vector method is applied to analyze and calculate the positive and negative solutions of the location,speed and acceleration of the output end of the metamorphic mechanism,analyzing the singular position of every configuration of the metamorphic mechanism through using Jacobian matrix,and the workspace boundary condition of the metamorphic mechanism is solved by combining with the existence theorem of implicit function,the practicability of the above results is verified by numerical simulation,and the effective workspace of the each structure of the metamorphic mechanism is obtained by the simulation undering the singular configuration and boundary condition of the mechanism.Then,According to the expression of centroid position and centroid velocity of each bar,the kinetic energy and potential energy of each bar of the mechanism are calculated,and the kinetic energy and potential energy of the novel three configuration metamorphic mechanism are obtained by counting summation,the rigid body dynamic equation of the metamorphic mechanism is constructed by using Lagrange method,after its analytical solution is obtained,the Matlab software is used for simulation analysis.Finally,under the condition of getting the beam element mass matrix and the stiffness matrix,the finite element model of each configuration of the metamorphic mechanism is established,the mass matrix and stiffness matrix of every configuration system of the metamorphic mechanism are obtained by counting summation of mass matrix and stiffness matrix of the beam element.And the elastic dynamics modeling is builded by using the finite element method,then Peter Newmark(Newmark)method is used for solving the elastic dynamics equation,and Matlab software is used for carrying out the numerical simulation analysis.Through the above research on kinematics and dynamics of the novel three configuration metamorphic mechanism,it lays a solid theoretical foundation for application in engineering practice.