Design And Characteristic Analysis Of A Quasi-zero Stiffness Isolator With Adjustable Load

Under the excitation of shafting,propeller operation and waves,the ship will cause the vibration of the overall or local structure and the pipeline system,causing adverse effects.In order to reduce the harm caused by these vibrations,it is usually necessary to install vibration isolators between equipment,pipelines and foundations.Traditional linear vibration isolators usually achieve vibration isolation effects only for a specific load,and because of their own characteristics,it is difficult to isolate low-frequency vibrations.Therefore,this paper designed an adjustable load quasi-zero stiffness vibration isolator,and through theoretical analysis To test static and dynamic characteristics,study the mechanical characteristics and vibration isolation performance of quasi-zero stiffness vibration isolator.The main work content and conclusion of the paper are as follows:First,the main spring and auxiliary spring connected in parallel are combined through a cam and a roller device.By reasonably setting the cam curve,a low-frequency vibration isolator with quasi-zero stiffness characteristics is designed.The expression of the restoring force of the quasi-zero stiffness system is constructed by introducing the Gaussian function,and then the system is statically analyzed.The calculation method of the cam profile that meets the system restoring force expression is given by Matlab,and the realization method of adjustable load of quasi-zero stiffness isolator is explained.Then,the design and optimization of the cam,which is the key component of the zero stiffness isolator,are discussed,and the main and auxiliary spring models and cam profiles of the quasi-zero stiffness isolator are determined.The static check of the designed cam is carried out.The results show that both the output load and the working angle of the cam meet the design requirements.At the same time,the geometric shape and working angle of the cam are taken as the targets to further analyze the influence of different parameters on the cam when the system parameters are adjustable.Next,the Averaging method is used to solve the differential equation of motion of the quasi-zero stiffness isolator,and the expressions of the system’s amplitude-frequency response equation with the force transmission rate are obtained,then the effects of different parameters on the dynamic characteristics of the system are discussed comparing with other vibration isolation systems.The results show that the dynamic response and transmission rate of the quasi-zero stiffness isolator system designed in this paper are the same as the Duffing system.They are not only related to the external excitation frequency,but also related to the external excitation load amplitude,and it will also appear under different parameters,the obvious jump phenomenon.Finally,Static and dynamic test are carried out on the processed quasi-zero stiffness isolators designed in this paper.Through the static test,the force-displacement curve output by the isolator under different loads is obtained,and the equilibrium position of the system is determined.Then,a dynamic test platform for quasi-zero stiffness isolators is built,and vibration tests under different excitation amplitudes and frequencies are performed to analyze the transmission rate characteristics of the system under the excitation of simple harmonic force.