Design And Analysis Of Non-Equal Section Large Deformation Structure With High Static And Low Dynamic Stiffness

Vibration of industrial production,especially precision engineering has many hazards.When the vibration exceeds the allowable range,the mechanical parts are prone to stress concentration and fatigue failure,reducing the life of the parts.In the manufacturing process,the vibration will affect the machining accuracy.So the research of vibration reduction theory and the design of vibration isolator have been the focus of research.Many areas have an urgent need for vibration isolator with a low frequency or even ultra-low frequency vibration isolation capability and a wide range of vibration isolation frequency.When the Euler strut generates large deformation due to axial force,its stiffness will be rapidly reduced.This feature can be used to design vibration isolator based on large deformation structure.This isolator has a simple structure,it has both high static stiffness and very low dynamic stiffness,can be used for low frequency vibration isolation.Firstly,the first order differential equations of curved beams subjected to the end force are deduced in this paper.The equations are solved under different initial conditions and boundary conditions,and the variation of the load capacity and stiffness is analyzed.The results of the solution are compared with those of the finite element method to verify the correctness of the deduced results.Secondly,two kinds of high static and low dynamic large deformation structure models with different cross-section types are established.The influence of different cross-section parameters on the structural load capacity and stiffness is analyzed.The results show that increasing the width of the cross section at the symmetry axis,the width at the ends of cross section and reducing the height of the cross section can increase the load capacity and stiffness of the structure.The increase of the width of cross section at the symmetry axis can improve the load capacity without significantly increasing the stress within a certain range of change.Appropriate reduction of the initial curvature of the section can improve the static-dynamic stiffness ratio in the process of structural deformation.Discussed the principles in the design of the section and the problems that should be paid attention to.The two cross section types of large deformation structure are compared,indicating that the hyperbolic section large deformation structure can reduce the stress after deformation,but also maintain a high staticdynamic stiffness ratio.Finally,based on the analysis of the previous chapters,a large deformation structure with extremely high static-dynamic stiffness ratio is designed,and its load capacity and stiffness are analyzed.In the axial direction of 0.05% to 2% deformation,the stiffness of the structure decreased by 98.91%,and the large deformation structure has a very low dynamic stiffness.The dynamic analysis of the structure is carried out,indicating that the structure has a very low natural frequency and can be used for low frequency vibration isolation.