A Magnetic-mechanical-thermal Multiphysical Model Of Magnetorheological Dampers And Its Application In Vibration Control

Magnetorheological Fluid is a new type of intelligent material.Under the action of an external magnetic field,a free-flowing liquid can change from a liquid state to a semisolid state in milliseconds with the increase of the magnetic field strength,and the change process is reversible.Magnetorheological damper is a kind of intelligent damper developed by using the magnetic field,the magnetorheological fluid can quickly undergo reversible rheology.It has the advantages of low energy consumption,fast response speed and continuously adjustable damping force.It is an ideal damping member in structural vibration reduction.When the MR damper works,it has magnetic field,fluid force field and heat conduction,so this paper establishes a magnetic-mechanical-thermal multiphysical model and proposes a semi-active control algorithm based on the MR damper physical model.(1)In the MR damper,the magnetic field generated when the current changes is unevenly distributed in each steel material component.Previous studies have mostly used finite element analysis to simulate the magnetic field change in the MR damper.In view of the shortcomings such as the time-consuming calculation of the finite element method,this paper proposes a dynamic magnetic field model based on the distributed parameter method.By layering each steel material component in the magnetic circuit,the error caused by the uneven magnetic field distribution is effectively reduced.For the magnetic field in each layered component,establish a circuit system consisting of equivalent inductance,resistance and power supply.The model is efficient in solving and the results are intuitive and easy to understand.The hydrodynamic model in the literature is used.This hydrodynamic model also uses the distributed parameter method,and is easily coupled with the magnetic field and heat transfer,which can more fully reflect the actual dynamic performance of the damper.Through the relationship between shear stress and magnetic induction intensity,the hydrodynamic model is coupled with the magnetic field model.Finally,the comparison with the experimental data of the MR damper response time shows that the magnetic-mechanical coupling model is reliable.(2)Based on the conservation equation of the control body,the heat transfer model of the MR damper is proposed in this paper.Combined with the distributed parameter method,the left and right chambers and gaps of the MR damper are divided into several control bodies,each of which meets the conservation of mass,momentum and energy,and the adjacent control bodies are connected by boundary conditions to establish a heat transfer model based on the control body.The reliability of the heat transfer model is verified by the temperature rise test of the MR damper.The results show that the temperature rise rate of the MR damper is fast under high current,and the heat transfer model proposed can accurately predict the temperature change of the MR damper.Compared with the existing research,the heat transfer model can better simulate the heat conduction caused by convection between the left and right chambers by considering the movement of the piston.This model has important practical significance for further research on heat transfer design and analysis of MR dampers.(3)In the existing semi-active control algorithm of MR dampers,the mechanical model of the damper used is often a phenomenological model.Although this model has the advantage of simple calculation,it requires parameter identification through experimental data.So it only applies to the dampers that have been built and tested.The relationship between the physical parameters and the control effect in the damper is unclear.In view of this,this paper proposes a semi-active control algorithm based on the physical model of the MR damper.For the three-layer frame structure in the literature,the effect of semi-active control is preliminarily investigated,and compared with uncontrolled and passive control.The results show that the semi-active control algorithm based on the physical model is feasible,and the semi-active control effect is also good.Finally,it is shown that the proposed semi-active algorithm can be used to directly investigate the influence of physical parameters in the damper on the control effect.