Study On Optimum Design And Vibration Isolation Performance Of Inerter-rubber Composite Vibration Isolator

The vibration isolator is an indispensable part of the ship and marine power machinery equipment,in order to ensure the safety work of the power machine,most of these mechanical equipment adopts the rubber isolator to isolate the vibration between the foundation and the equipment,but the rubber isolatorhas disadventages of poor performance of low-frequencyvibration isolation,so the introduction of new methods to re-develop a new type of rubber isolator is necessary.In 2001,Cambridge scholar Smith invented the inerter,providing a new ideafor the vibration isolation of low-frequency,this article uses that inerter has a good performance of low-frequency vibration isolation,introducinginerter into the design of rubber vibration isolatorand carrying out the calibration,optimization and experimental study.Providing the theoretical basis and practical reference for the further design and improvement of the inerter-rubber composite vibration isolator.The main contents of this article are as follows:(1)A method for calculating the inertance of ball-screw inerterwhich considering nonlinear factors.Based on the Frent theory and the Hertz contact theory,the differential velocity between the balls and the raceways in the ball-screw inerter is deduced,the friction efficiency between the balls and the raceways is deduced,getting the nonlinear inertancecalculation method.The experimental results show that the nonlinear inertance is closer to the experimental value,and the accuracy of the method is proved.In addition,the influence of some parameters of the ball screw mechanism on the inertance is analyzed.The results show that the smaller the lead,the smaller the nominal radius,the bigger the ball radius,the smaller the number of balls,the smaller the contact angle,the bigger the inertance.The results of these studies are beneficial to the precision design of ball-screw inerter and its application in engineering vibration isolation system.(2)Designing a kind of composite vibration isolator product that inerter parallel with metal-rubber compound(inerter-rubber composite vibration isolator).Based on the vibration theory,the type Ⅱ ISD vibration isolation system was analyzed,and obtaining the best inertance-mass ratio and damping ratio.Selecting 5DK-20 diesel generator set as design object.According to the relevant manual,the ball screw mechanism in the inerter was designed in detail,including the specific size of the ball screw mechanism and parameters of mechanical performance.The outer dimensions and performance parameters of the flywheel,the top cover,the base,the metal-rubber compound and the through-bolt are designed in detail,and the inerter-rubber composite vibration isolator shown in the appendix.In addition,the mechanical properties of the inerter-rubber composite vibration isolator are analyzed,including the analysis of the natural frequency analysis,the strength,the stiffness and the stability.The optimal number of the balls is discussed from the mechanical point of view.providing a specific design methodof inerter-rubber composite vibration isolatorfor the engineering design staff,with practical engineering significance.(3)Related parameters of the inerter-rubber composite vibration isolator was optimized.From the two aspects includingperformance of vibration isolation and service life,a mathematical model of inerter-rubbercomposite vibration isolator is established,which includes design variables(lead,nominal radius,ball radius,number of balls,contact angle between balls and raceways),geometric constraints and mechanical constraints,objective function(transmissbility,stable transmissbility,effective frequency ratio,service life).Based on genetic algorithm,the crossover probability and mutation probability which are most suitable for the mathematical model are analyzed.According to the difference between the performance of vibration isolation and the service life,the different weights are set for the total objective function,and the different weights are analyzed synthetically,and the best scheme of the total objective function value is obtained which provides the method guidance and the theoretical support for the optimization design of the inerter-rubbercomposite vibration isolator.(4)The static and dynamic performance of the inerter-rubber composite vibration isolator is analyzed experimentally.The static and dynamic experimental schemes of the inerter-rubbercomposite vibration isolator are designed.The static stiffness,dynamic stiffness and influence of inertanceonperformance of vibration isolation are analyzed.In addition,based on the experimental results,the concept of complex mass is defined,and the governing differential equation of the inerter-rubber composite vibration isolator is re-constructed and transmissbility is re-deduced.The results show that targeted at the vibration isolator paralling with inerter and rubber,transmissbility deduced in this paper is more accurate than the classical ISD vibration isolation system.The results of the study provide guidance on the theory of performance of vibration isolation,which is beneficial to the design of inerter-rubber composite vibration isolator.In this article,the calculation method of the nonlinear inertance of the ball-screw inerter,the design method of the inerter-rubber composite vibration isolator,the 3D modeling and the finite element modeling method,the mechanical properties analysis and verification method,optimization of relevant parameters design method,static and dynamic performance of experimental research methodare studied systematically..The research results have important theoretical and engineering value for the design and application of the guidance and inerter-rubber composite vibration isolator.