Research On Construction Theory And Mechanical Properties Of Compliant Constant Force Platform Based On Superposition Of Positive And Negative Stiffness

Compliant constant force mechanism can realize constant force output mechanism without using external sensors and actuators,and realize movement,force and energy transmission and conversion by means of deformation of flexible rod members.It has the advantages of no friction and impact at the side of movement,high movement precision of mechanism,convenience for overall processing and easy miniaturization,and has wide application in the fields of micro-mechanical systems,precision machinery,medical machinery and the like.Based on the compliant beam with positive stiffness and the flexible bistable beam with negative stiffness,a new compliant constant force mechanism is constructed in this paper.The main work is as follows:The basic design and calculation method of the compliant constant force mechanism is described.The equivalent spring stiffness of U-shaped compliant straight beam with positive stiffness characteristic is established by using pseudo rigid body model.The force-displacement theoretical model of compliant bi-stable beam is introduced,and the calculation method of local negative stiffness is obtained.Further,the design calculation method of compliant platform with zero stiffness characteristic is obtained by using positive and negative stiffness superposition principle,and the design calculation method of compliant constant force mechanism is verified by using finite element tool.In order to obtain the ideal constant force region and constant force magnitude,the structural parameters of the compliant constant force platform are optimized.Considering the overall structural dimensions of the compliant platform,the structural parameters of U-shaped compliant straight beam and compliant bi-stable beam are selected and discretized.The finite element tool is used to calculate and analyze the stress-displacement relationship curves of each discrete structural parameter,and optimize the structural parameters of the composite compliant beam to obtain the ideal constant force region and constant force magnitude.The dynamic characteristics of the compliant constant force platform are studied.A three-dimensional model of the compliant platform is constructed,and its modal,dynamic stress and strain,harmonic response,fatigue strength and other characteristics are analyzed based on finite element analysis method,which provides necessary reference for the practical application of the compliant platform.Based on the design principle that positive stiffness and negative stiffness are superposed to construct a compliant constant force platform,the application range of compliant bistable mechanisms is expanded,and the design method of compliant mechanisms is enriched.Figure [62] able [7] reference [80]...