Design And Analysis Of Low Frequency And Large Bandwidth Damper Based On Nonlinear Array Structure

Automobile vibration is an important factor affecting its comfort performance,which has the characteristics of multi-vibration source,low frequency and wide frequency band.The traditional linear damper is difficult to meet the requirements of large bandwidth damping due to its single-frequency point damping performance.Recent studies have shown that nonlinear structures exhibit excellent performance in attenuating low frequency and large bandwidth vibrations.The difficulty lies in how to obtain a nonlinear structure with specific mechanical properties to meet the vibration damping requirements of a specific frequency band.For this reason,a nonlinear variable stiffness adjustment method based on partial section configuration transformation is proposed,and a nonlinear bistable unit cell structure with large bandwidth is designed.Then,the dynamic characteristics of multi-array structure and its vibration reduction is analyzed.The specific work includes:(1)A variable stiffness adjustment method for pre-compressed variable-section bistable cosine beam structure is proposed.Based on the large deformation finite element theory,the jump characteristics of prestressed bistable beam with multiple variable cross sections are analyzed.The relationship between the jumping properties and geometric characteristics including size,arrangement and extrusion amount on the bistable beam is analyzed.Then,the variable-section bistable beam configuration with specific mechanical properties and its control method are obtained for achieving specific nonlinear variable stiffness.(2)The dynamic analysis model of the variable-section pre-compressed bistable cosine beam is established.By means of nonlinear finite element theory,the adjustment method for bistable jumpping bandwidth is proposed.The influences of excitation amplitude,frequency,load position and extrusion displacement on dynamic bifurcation characteristics have been analyzed.The bandwidth is 9.4 times of the first-order bandwidth of the bistable structure with uniform cross-section.In order to facilitate the experimental verification,a large-scale experimental sample is fabricated.The experimental damping bandwidth is 35.1 Hz,which is almost the same as the simulated value of 34.9 Hz.The bandwidth fundamental frequency ratio is 1.61(simulation is 1.56)at this size.The effectiveness of the proposed large bandwidth nonlinear structure design method;(3)The design scheme of nonlinear vibration-damping structure with multi-cells is proposed.The key parameters influencing the static characteristics of the array structure aredetermined.The dynamic simulation results show that the bandwidth of the variable-section cosine beam structure is 4.12 times of the uniform section structure,which can be used for designing high performance automotive shock absorbers.