Study On Fluid-solid Coupling Of Underwater Shaking Table And Control System Modeling

The performance of marine equipment working under water needs to be determined through underwater testing,so underwater vibration environment simulation test is needed.As an important experimental equipment for simulating the underwater vibration environment,the underwater shaking table has been widely used in the underwater seismic performance test of civil construction and the anti-vibration performance test of underwater equipment.Underwater shaking table simulates the underwater environment by controlling motion of the table,testing the seismic performance and underwater performance of the device connected to the surface.Underwater shaking table will inevitably be subjected to the fluid resistance in the underwater movement,driving the nearby fluid to vibrate.Due to the fluid's quality,this process is equivalent to adding additional mass to the mesa.When the additional mass is considered,the system bandwidth will be reduced and there will be a resonant peak in the system frequency response.Aiming at this phenomenon,this paper proposes a three-parameter pole configuration self-tuning controller,which will ensure the system's dynamic indicators by assigning the system's pole adaptively.The main work of this paper is as follows:First of all,the development status of underwater shaking table is introduced and the research overview of fluid-solid coupling and shaker control system is briefly described.The working principle and composition of the shaking table system are described,and then the characteristics of the dynamic mechanism of the electro-hydraulic servo shaking table are analyzed.Then the three-parameter control strategy of shaker is studied emphatically,and it is found that the three-parameter control can effectively expand the bandwidth of the system and reduce the resonance peak.Secondly,the basic theory of fluid finite element method is used to analyze the fluid-structure interaction mechanism of the shaking table in detail and establish the mathematical model of fluid-solid coupling.The hydrodynamic force of underwater shaking table under different input signals is calculated by numerical simulation of fluid,and then the relationship between excitation frequency and additional mass is specified.It is found that the system bandwidth is reduced and there is a resonant peak again in the system frequency response when the additional mass is considered.Thirdly,a pole placement self-tuning controller is proposed for reducing the influence of additional mass on the control system of underwater shaking table.The principle of pole placement self-tuning control is analyzed in detail and the simulation case shows the working process of the pole configuration self-tuning controller and verifies the performance of the controller.Finally,the three-parameter control is combined with the pole-placement self-tuning controller and the control law of three-parameter pole placement self-tuning is deduced.Then,the underwater shaking table control system is modeled by Simulink.And finally,the feasibility of the control system is verified through the simulation of the sine vibration and the swept-frequency vibration of the underwater shaking table.