Study On Horizontal Ball Pendulum Isolation With Optimized Changing Curvature Surface

Nearly 30 years,at home and abroad for a variety of different types for different target levels of isolation method,after several destructive earthquake has played an important role,but also exposed some problems,such as isolation device since the reset problem,the surface under the condition of large displacement resonance problem,cause based on the traditional circular arc surface trajectory with fixed vibration period characteristics of sliding friction pendulum isolation device has certain risk of failure.Obviously,if the pendulum with changing curvature surface is adopted,the stiffness can be reduced with the increase of displacement easily.In other words,the stiffness softening mechanism can be provided.After reasonable design,the pendulum type isolation device can have non-fixed isolation period,which can avoid the quasi-resonance problem caused by long period and low frequency vibration.If the rolling friction device is used at the same time,the problem of self-reset can be solved.Aiming at the above two problems,two kinds of horizontal vibration isolation methods based on variable frequency spherical pendulum and conical spherical pendulum are studied in this paper.The main research contents include the following four aspects:1.Literature review and question introduction.The seismic damage of cultural relics,equipment and other sensitive non-structural objects and the types of common isolation devices are reviewed.This paper summarizes the research and development of isolation technology for equipment and cultural objects at home and abroad,finds out the advantages of changing curvature surface and its application vacancy in the research of rolling isolation device,and studies the feasibility of combining changing curvature surface with good self-recovery ability of rolling support.2.A method of horizontal isolation of spherical pendulum with changing curvature is proposed.Based on the basic principle of rolling isolation,a simplified model of ball pendulum is established and its motion equation is deduced.The parameter optimization numerical simulation of spherical pendulum isolation device with changing curvature is realized by Matlab programming.A large number of numerical simulation analysis is carried out for the horizontal isolation model with different surface parameters,and the results show that the frequency conversion and conical surface have better isolation efficiency.3.Two kinds of shaking table tests of spherical pendulum isolator with changing curvature are designed and completed.Four sets of variable-frequency ball pendulum and conical ball pendulum devices with different parameters were designed and manufactured,and viscous dampers with different parameters were installed to compare the isolation effects of devices with different energy dissipation capacities.Two kinds of spherical pendulum devices were tested by three-way excitation simulated shaking table.The results show that the two kinds of spherical pendulum devices have good isolation performance,and the rule that the isolation performance varies with the change of parameters is verified.4.Two kinds of parameter optimization design methods for spherical pendulum devices with changing curvature are presented.By comparing the numerical simulation results with the shaking table test results,the accuracy of the numerical simulation to reflect the actual motion of the spherical pendulum device with changing curvature is verified.The optimal design methods and Suggestions for the surface parameters,rolling friction coefficient,initial isolation period and additional damping of the two types of supports are given.