Study On The Design And Modeling Of Nonlinear Vibration And Shock Isolator

The equipments bear not only the periodic oscillating load but the shock load, and the shock load often does more destruction than vibration itself. To reduce the destruction, it is better to take measures to protect or isolate the equipment. The effect of the protection or isolation depends on the performance of the isolators and the match of the system parameters. In most cases, it does not take the system's anti-shock ability into consideration when design. So it is necessary to investigate the anti-shock ability of the isolation system and to develop new isolators.Under the support of the project"The study on the performance, theory of modeling and design of new shock isolator", the author accomplishes the research on performance of the single degree of freedom which contains different damping deduces the relationship between index of anti-shock performance and system parameters, and compares anti-shock performance of the different systems. Based on these, the author designs a novel nonlinear vibration and shock isolator. Then the nonlinear mathematical model of the isolator was established and the parameter of the model was identified.The main research work and conclusions are as follows:1 In the paper, the author reviews some research methods and current research status on the parameter optimization of shock isolation, some common isolators'mechanism, the characteristic of the structure, mathematic model, and their application in industry. 2 Many efforts are put on the anti-shock performance of linear damping system (linear stiffness in parallel with linear damping), quadratic damping (linear stiffness in parallel with quadratic damping) and Coulomb damping system (linear stiffness in parallel with Coulomb damping), deduces the condition when these systems show the optimal anti-shock performance. The optimal anti-shock performance of different systems is also compared.3 A novel nonlinear vibration and shock isolator was designed whose restoring force is supported by the elasticity of the elastomer, and damping force is produced by the viscosity of the elastomer and the friction on contact surfaces. Then the finite element model is built, which is important to confirm the key parameters. The dynamic and static simulation to the isolator shows the stiffness characteristic of the isolator is hard.4 According to the simulation results of the designed vibration and shock isolator, the two nonlinear mathematical models are established to simulate the vibration performance of the isolator. One is based on force-displacement hysteresis curve, and the Bouc-Wen model is introduced to describe the curve. The other is based on frequency response curve. The effect of the parameters of different models to the isolator is studied5 The identification methods to the two models are presented. An experimental sample of the isolator is created, and the characteristic curve is tested which is accordance with the result of finite elements simulation, that validates the validity of the finite element model. Based on these, the unknown parameters of the two models are identified. With these parameters the numerical simulation of the forced vibration response with different original conditions and different excitation frequency are calculated. The result shows that the free vibration's frequencies of the two models agree well, while the forced vibration amplitudes of the models are consistent. All these prove it is feasible to model the vibration performance of the isolator using the two models referred and the identification methods are valid.6 The nonlinear mathematical model of anti-shock performance is established, and the shock responses of the isolator are caculated under different shock input. The shock experiment is made on the drop test platform, which validates the feasibility of the mathematical model.