Study On Performance Of Vibration Isolation And Optimization Of The Distribution Two-stage Vibration Isolation System

Two-stage vibration isolation system is an effective method to isolate vibration in mid-high frequency,which is widely used in ships,cars,spacecraft and other fields.With the development of vibration isolation technology,good vibration isolation effect with a light intermediate stand has become a trend,but lightly intermediate stand may bring some more flexible body mode in mid-high frequency,which makes vibration isolation effect worse.As to this problem,distribution intermediate stand vibration isolation system has become a new choose.Based on the previous studies,this paper has designed the distribution two-stage vibration isolation equipment,and reaserch the law of isolation vibration of the integral two-stage vibration isolation system and the distribution two-stage vibration isolation system by using theoretical and testing.Main research contents and results are as follows:(1)Design integral and distribution two-stage vibration isolation system testing equipment,which uesd to verify the vibration isolation effect and transfer mechanism of the distribution and integral two-stage vibration isolation model.Testing equipment contains upper quality equipment,upper and lower vibration isolators,integral and distribution intermediate stand and base system.The excitation source of two systems are provide by vibrator,by moving the position of the vibrator and upper quality equipment,the vibration isolation effect and transfer mechanism in complex conditation could be researched.At the same time,researched the kinetic characteristic of simplified model of the testing equipment by using numerical analysis,and compared to the Abaqus and testing,the error is within control.Finally,tested the dynamic stiffness of vibration isolator.(2)Based on the impedance/admittance mothed,built the calculation model of integral and distribution two-stage vibration isolation systems,and the power flow is used as the evaluation function.And researched the transfer mechanism of these two vibration isolation systems in complex cases.Research shows that the change of the mass center eccentricity of upper quality equipment makes the model frequency of changed,and in different conditions of eccentricity of excitation force,the degree of excitation of system model frequency is also different.When the eccentricity of excitation force is small,the model frequency of superstructure symmetry system is obviously inspired in middle frequency,and with the increase of the mass center eccentricity of upper quality equipment,the degree of excitation become weaken,the amplitude of power flow become small;and when the eccentricity of excitation force is large,with the increase of the mass center eccentricity of upper quality equipment,the degree of excitation of system model frequency become obvious,the amplitude of power flow become big.When the upper quality equipment is symmetrical,with the increase of eccentricity of excitation force,the power flow amplitude of both vibration isolation systems becomes big in low frequency and first become small and then becomes big in mid-high frequency;when the mass center eccentricity of upper quality equipment is 5%,the power flow amplitude first becomes small and then becomes big in mid-high frequency and when the mass center eccentricity of upper quality equipment is 9%,the power flow amplitude becomes big in mid-high frequency.Though the comparation of integral and distribution two-stage vibration isolation systems under the same conditions,whatever the position that exciting force relative to center of mass or the mass center eccentricity of upper quality equipment,distribution two-stage vibration isolation system is better than integral two-stage vibration isolation system,meanwhile,distribution two-stage vibration isolation system has obviously suppression to the flexible body mode of the base plate.In the same case of exciting force and the mass center eccentricity,keep the mass ratio of integral two-stage vibration isolation system and reduced the mass ratio of distribution two-stage vibration isolation system,when the mass ratio of distribution system is 27%,the vibration isolation effect of distribution vibration isolation system is rather than integral vibration isolation system.Though the comparation of different distribution blocks,the system that install eight 15 kg blocks is better than six 20 kg blocks.(3)Using the GA algorithm toolbox in MATLAB,built the installation position optimization model about four 15 kg blocks and six 15 kg blocks.Research shows that when install four 15 kg blocks or six 15 kg blocks,with the tnstallation position close to the center of system,the vibration isolation effect become better but in symmetry system,the optimization results is not symmetry in center of system,it's decentration.(4)Built the integral and distribution two-stage vibration isolation equipment,and tested the vibration isolation effect of two vibration isolation equipment,with the contitadions as the mass center eccentricity change of upper quality equipment and integral intermediate stand,the position that exciting force relative to center of mass change,reduce the mass ratio of distribution two-stage vibration isolation system,different mass distribution blocks and install psotition change about 15 kg blocks.Research shows the change rule of testing results and theoretical calculations are basically matched in 10-1000 Hz.When the mass center eccentricity and eccentricity of excitation force is small,the both vibration isolation effect becomes better,and When the mass center eccentricity and eccentricity of excitation force is big,the both vibration isolation effect becomes worse.In the same conditions,the distribution two-stage vibration isolation is better than integral two-stage vibration isolation about 8-9dB in 50-1000 Hz,it also proved that it's feasible to consider the distribution block as a rigid body model;Because of the model frequency of distribution blocks in 1000-2000 Hz,the advantage of vibration isolation effect is obviously decline.When the mass ratio of distribution two-stage vibration isolation system is 20%,the vibration isolation is equal than integral two-stage vibration isolation systems with the mass ratio 50%.Compared the installation position of four 15 kg blocks and six 15 kg blocks,with the installation position close to the center of vibration isolation system,the effect of vibration isolation system become better,but it's not apply to engineering application.So,in satisfaction of engineering application,it can be installate close to the center of system as possible.