Dynamics Analysis And Experimental Research On Planar Four-bar Mechanism With Clearance And Flexible Link

The pair clearance and flexibility of link are unavoidable problems in the application of the mechanism.The mechanism is composed of different links.Excessive pair clearance will reduce the movement accuracy and increases wear of the system.It will lead to tight fit and increase resistance to movement if clearance is too small.The rigidity and flexibility of links are relative.In production practice,excessively improve the rigidity of link will increase the weight of link and driving power of mechanism.Excessively improve the flexibility of link will increase deviation of link and uncertainty for operation of the mechanism.The dissertation took two typical four-bar mechanisms as examples,namely the four-bar and crank-slider mechanism.The massless rod method was used to equivalent clearance to establish vector model of the four-bar mechanism with clearance.The connecting rod transformed flexible link used to discretization method.There was dynamic model of the planar four-bar mechanism with clearance and flexible connecting rod to be established.The influences of the joints clearances and link flexibility on the dynamics of two typical planar four-bar mechanisms have been represented.Based on the theoretical model,the ideas have been put forward concerning researching coupling function concerning rotating pair,translational pair and flexible connecting rod.And a combined planar four-bar mechanism experimental rig has been explored.The accelerations of connecting rod,follower and slider were measured to analyze the influence of different types and joints on the dynamic characteristics of rigid and flexible mechanism.The simulation model was established and experimental studies were applied to verify the correctness of the simulation model,and further guide theoretical simulation studies.The influence of two kinds of kinematic pairs including translational and rotational pairs,three different clearance values for on the dynamic characteristic of rigid and flexible mechanisms,which contains impact behavior,stability and accuracy,been researched in the dissertation.To meet different design demands,combined schemes were developed about different joints clearances and flexible link.And there are to provide the research basis for the next reasonable clearances combination and lightweight optimization of the connecting rod.