Research On Shock Resistance Of Passive And Semi-active Vibration Isolation System

With the increasing precision of modern equipment,people are increasingly demanding the impact resistance of equipment in the work process.In order to reduce the damage caused by impact,the equipment must be protected.Based on the wire rope isolator,this paper conducted theoretical and experimental research on the passive impact isolation system and the parallel isolation system with magnetorheological damper(MRD),aiming to reduce the impact response of the equipment.Firstly,the impact response of the single-degree-of-freedom linear vibration isolation system was solved based on the speed step method,and the influence of various factors on the impact response was analyzed.The basic structure of the impact isolation system using wire rope isolator was designed.Based on the solution result of the speed step method,the anti-shock design of the wire rope vibration isolation system is accomplished.The rationality of the speed step method in short impact calculation and design is verified by a specific example.Then,the frequency sweep test of the wire rope vibration isolation system was conducted under different excitation amplitudes,showing the trend that the wire rope vibration isolation system has strong nonlinear soft characteristics.Based on the results of frequency sweep test,the harmonics balance method was used to model and solve the dynamics of the vibration isolation system,and to identify the system model parameters.Through the impact simulation and test of the vibration isolation system,it is shown that the wire rope vibration isolation system has good impact resistance to high frequency impact and big amplitudes impact load.Finally,a MRD was applied to the impact isolation system.Based on the Bingham constitutive relation model of magnetorheological fluid(MRF),a parametric damping force model of shear valve MRD was established.Using the Ampere loop theorem,the approximate mathematical model of shear yield strength of MRF with input current was derived.Based on the dynamometer test of MRD,the parametric model of the MRD was verified and properly revised.After that,the impact simulation and test of the wire rope isolator parallel MRD were carried out.The results showed that,the acceleration response increases with the increase of the damper input current,while the relative displacement response decreases with the increase of the damper input current.Compared with the passive impact isolation device,the magnetorheological semi-active vibration isolation system can be adjusted according to different impact resistance requirements,which can reduce the system deformation under the premise of satisfying the isolation efficiency,and exhibits a wider applicability.