Research On The Configuration Method Of Compliant Mechanism Of Space Curved Beam And Negative Poisson’s Ratio Structure

The compliant mechanism has simple structure,less friction and wear,high motion accuracy,and can adapt to harsh working environment.It plays an important role in the frontier fields of bionic machinery,bio-medical treatment,precision engineering,aerospace and so on.The compliant mechanism with the curved beam as the flexible element is subjected to uniform force,which can avoid the stress concentration and has large working stroke.The curved beam is flexible in shape and can be arranged flexibly.At the same time,many geometric parameters of its own mechanical properties can be adjusted.Therefore,the compliant mechanism of the curved beam has been paid more and more attention by researchers.Based on the isogeometric analysis,the spatial curved beam is analyzed in this paper.In this paper,a fast method for designing a spatial compliant mechanism of curved beam with excellent performance is presented,and a negative poisson’s ratio structure is designed by using this method.By analyzing the structure,the effectiveness of the proposed method is verified,which provides a new theory for the design of negative poisson’s ratio structure.Space curved beam linear stiffness matrix formula is derived,application of differential geometry in the Frenet frame as a space of arbitrary curved beam local coordinate system,the NURBS basis function as the displacement shape function,linear stiffness matrix of spatial arbitrary curved beam is deduced,the author analyzes the single curved beam,and more pieces,the results compared with the finite element analysis results,verify the validity of the obtained formula is derived.Based on the stiffness matrix model of spatial arbitrary curved beam obtained by the isogeometric analysis,the performance indexes of stiffness ratio and adjoint displacement ratio are established to establish functional relations with geometric parameters of curved beam,and the spatial curved beam configuration library is constructed.According to the configuration library,the space curved beam with better performance can be selected as the compliant element.Combined with the complementary topology method of freedom and constraints,the space curved beam compliant mechanism with desired performance can be synthesized,providing theoretical basis for the design of the space curved beam compliant mechanism with excellent performance.Based on the proposed configuration method of spatial compliant mechanism for curved beam,a compliant mechanism for curved beam was designed.With the compliant mechanism as the cell,a spatial negative Poisson’s ratio structure was designed.The negative poisson’s ratio effect of the structure is verified by isometric analysis and finite element analysis.Thevalidity of the method is verified,and it also provides a new idea for the design of negative poisson’s ratio structure.Based on the linear model,geometrically nonlinear of space curved beam is studied,the tangent stiffness matrix of space curved beam under Kirchhoff hypothesis is given,the advantages of different nonlinear solving methods are analyzed,and the corresponding theory is provided for the study of space curved beam with large deformation.