Damping Control And Multi-field Coupling Dynamics For Twin-tube Hydraulic Composite Vibration Isolating System

As a key component of vehicle suspension system,hydraulic shock absorber plays an indispensable role in absorbing external road vibration.With the development of vibration control technology,a two-layer vibration control system with hydraulic shock absorber as the core and auxiliary series elastic isolator appears.Compared with single-layer vibration isolation system,double-layer vibration isolation system has broadband characteristics and better performance of high frequency vibration isolation.Inspired by the double-layer vibration isolation system,this paper proposes a kind of vibration absorption element with double-cylinder hydraulic shock absorber as the core.Graphene reinforced-functional graded porous,GPL-FGP)Twin tube Hydraulic Composite（THC）vibration isolating system of vibration isolation structure.In view of the current problems that failure mechanism of THC vibration isolating system is not clear,dynamic characteristics are not clarified,and damping control strategy under failure problem is not paid attention to,this paper carried out research on multi-field coupling dynamics and damping control of THC vibration isolating system,and relevant research contents are as follows:Firstly,the multi-field coupling phenomenon of THC vibration isolation system is revealed.In order to clarify the coupling phenomenon,the coupling equation is established under the definition of global flow field.In order to construct the coupling equation,the energy balance of the coupling phenomenon is deduced through the fluid mechanics equation.A novel cavitation model is established by using schnerr＆Sauer mass transfer method in order to ensure the ability of the coupling equation to describe the cavitation dynamics.In addition,to solve the structural response problem in the coupled equation,the coupling constitutive equation of oil film and valve plate is constructed.To solve the multi-field coupling model,a parameter iteration strategy driven by computational fluid dynamics（CFD）is designed.Finally,based on the coupling model,the gas-liquid-solid coupling in the THC vibration isolation system is analyzed experimentally and numerically.The results show that the model can describe the complex relationship between the gas-liquid-solid coupling process and the damping force hysteresis.This study provides the accurate expression of damping force and damping coefficient for subsequent dynamic analysis and damping control respectively.Secondly,based on the expression of damping force of multi-field coupling model,the dynamic responses of 16 GPL-FGP vibration isolation structures to different multi-field coupling damping forces under the two working conditions of the THC vibration isolation systems are analyzed.To this end,a dynamic model of GPL-FGP vibration isolation structure under elastic boundary condition is established.The model is constructed based on first-order shear deformation theory and virtual spring technique,and the nonlinear terms of the model are linearized by orthogonal Jacobian polynomials.On this basis,rayleigh-Ritz method and Hamiltonian least energy principle are used to solve the linearized model.To verify the accuracy of the proposed method,a convergence study is performed and compared with published results.The forced vibration characteristics and transient response characteristics of GPL-FGP vibration isolation structure are analyzed under main THC vibration isolation system conditions.The analysis results provide the optimal GPL-FGP vibration isolation scheme under common THC vibration isolation system conditions,and the obtained scheme provides important guidance for the deployment of GPL-FGP vibration isolation structure into THC vibration isolation system.In addition,the dynamic model provides accurate mass,stiffness matrix,and dynamic expression for subsequent damping control studies.Finally,important parameters such as damping coefficient and mass stiffness matrix are provided based on the multi-field coupling model and dynamic model to form the controlled state equation of THC vibration isolation structure.Based on the state equation,a probabilistic adaptive dynamic programming method was proposed for the effectiveness of damping control strategy when THC vibration isolation system failed,and the failure behavior of THC vibration isolation system was regarded as a kind of unbounded uncertainty.An optimal failure prediction controller was designed based on the method.Firstly,the conditions of stability and optimizability of damping controller under unbounded uncertainty are analyzed,and then the iterative method of probabilistic control strategy is constructed.Based on the proposed iterative method,the critical safety guarantee of THC vibration isolation system is formed,and the HJB equation constrained by the control barrier equation and the control Lyapounov equation is solved,so as to obtain the optimal failure prediction controller.Simulation results verify the feasibility of the proposed method,and compared with the existing adaptive dynamic programming method,the dynamic damping strategy of THC vibration isolation system obtained by the probabilistic adaptive dynamic method has better dynamic performance.It can not only accelerate the stabilization speed of the controlled system,but also take into account the reliability problems caused by the adjustment process of the optimal controller.