Random Dynamic Behavior Of Non-Smooth Vibration Isolation System Under Foundation Excitation

The structure of engineering equipment and system environment become more and more complicated to make the coupled dynamic behaviors be typically nonlinear and random.Meanwhile,the boresome responses reduce safety and reliability,resulting in malfunctions.Therefore,it is of significance to investigate the response mechanism of the vibration isolation system with random.This thesis takes the non-smooth vibration isolation system as the research object and analyzes the influence of the parameters on the global structure from the three aspects of determining the global,random excitation and random parameters,and the complex problems in the non-smooth vibration isolation system caused by random factors.Non-linear phenomenon.The main research work of this thesis is as follows:A vibration isolation system with non-smooth characteristic limiters is established under a deterministic framework,based on global dynamics theory and nonlinear analysis methods,combined with the global structure of the deterministic system,the research Non-linear response behavior of vibration isolation system.The results show that the system has multiple response characteristics of coexistence of stable responses with different periods in certain parameter areas,including collision-free response,symmetrical single collision and two-way collision response.Meanwhile,the range of collision-free response is also expanded as the parameters change.A dynamic model of the vibration isolation system with piecewise smooth characteristics under random excitation is established,and the random Monte-Carlo method is used to study the response characteristics of the vibration isolation system and the evolution behavior of its transient probability.The results show that under noise disturbance,the system under different parameters has a random transition from one response to another.Meanwhile,noise intensity and system parameters can affect the speed of the system’s transient response probability transition,resulting in a collision phenomenon in the vibration isolation system.Based on the polynomial chaos expansion(PCE)technique,from the perspective of random parameters,the impact of the uncertainty of bearing damping and stiffness coefficients on the nonlinear dynamic behavior of the vibration isolation system is focused on.The specific performance is:the probability density of the steady-state response of the damping and stiffness coefficients is distributed in one Within a wider range.The change of the intensity of Gaussian white noise can induce the parameters to evolve the probability density function from the initial unimodal response to the bimodal form,leading to probabilistic P-bifurcation behavior,which may cause random jumps in the system under disturbance.