| Cantilever beams,as a mechanical component,have broad application scenarios in practical design and engineering applications,and many components can be simplified as cantilever beam models for analysis.However,it is difficult to avoid vibration in practical applications of cantilever beams.In order to reduce the vibration of cantilever beams,a variety of damping methods are used to limit the vibration and nonlinear vibration absorbers are often used to reduce the vibration of cantilever beams.This thesis is supported by the General Project of Shaanxi Province Key R&D Program(2019GY-067)to study cantilever beams,which are often used in engineering,and aims to reduce the vibration generated during its practical application.First,by conducting modal tests on the cantilever beam,the damping mode of the cantilever beam is determined and the location of the maximum amplitude of the cantilever beam is determined.On the basis of this assumption,a dynamic vibration absorber of the thin-plate spring type was designed.Subsequently,combined with nonlinear vibration reduction theory,the thin plate spring type dynamic vibration absorber was optimized into a thin plate spring type nonlinear vibration absorber with segmented linear stiffness.In addition,the vibration reduction effect of the proposed damper has been experimentally proven.The main research content of this article is as follows:(1)The theoretical values,simulated values,experimental values and vibration modes of the first six natural frequencies of the cantilever beam were obtained by performing theoretical calculations,finite element simulations and hammer impact experiments on the investigated cantilever beam.The vibration pattern derived from the finite element simulation summarises the position of the maximum amplitude of the cantilever beam,which provided the basis for the hammering method and subsequent vibration experiments.In addition,by comparing the three natural frequencies,the vibration reduction mode of the cantilever beam is determined,providing a basis for the design of the vibration absorber.(2)Design a dynamic absorber based on the parameters of the cantilever beam and the vibration reduction mode.This article determines the mass ratio and optimal frequency ratio of the absorber based on the design criteria of the dynamic absorber.In addition,it has been found that the vibration absorber studied in this article is a thin-plate spring type vibration absorber with a variable cross section.The dimensions and material parameters of each accessory of the vibration absorber were given,and modal analysis was conducted on the dynamic vibration absorber.(3)It is improved into a thin plate spring type nonlinear vibration absorber with segmented linear stiffness based on the dynamic vibration absorber combined with the theory of nonlinear vibration reduction.Vibration experiments have been carried out to verify the damping effect of the designed dynamic and non-linear vibration absorbers in terms of acceleration and energy transfer respectively.In addition,the effect of changing the parameters of the segmental linear system on the damping effect is also investigated.Finally,the variation curves of the intrinsic frequency and amplitude decay of the cantilever beam after attaching a non-linear absorber are analysed. |
