The Study On Isolation Characteristics Of A Engine Mount With Electrorheological Fluids

Electrorheological fluids is a sort of smart material that have long term potential and engineering application worth.With the effect of external applied electric field,high performance electrorheological fluid is able to produce obvious electrorheological effect,that is to say proceeding quickly and reversiblely transform at liquid state and solid state,and keet viscosity continue,stepless change.The whole conversion process complete in a millisecond,furthermore electrorheological fluids are able to conveniently realize computer real time semiactive control.The basic idea of semiactive control is through the medium of transfer dynamic characteristics (as stiffness, damping and so on) to consume vibration energy, consequently realize vibration isolation and vibration reduction. Compared to the active control, the structure of semiactive control is simplified enormously,in addition dispensing with external energy source,loss of energy is little,although in control performance semiactive control is not as ideal as active control,its control quality has been close to active control;by comparison to passive type,mount structural parameters can make relevant changes according to working conditions,possessing higher performance.First of all the text introduces gist of selecting subject and subject background condition,summarily analyze study purpose and engineering applications value,based on reading a great deal of documentaries,reviews electrorheological technical develop situation and present status,introduces electrorheological technology application situation in vibration control engineering.Subsequently,it introduces composition of electrorheological fluids,analyses theory of electrorheological effect,emphasizely analyses the particle polarized principle,and proceeds detailed analyses on shear resistant yield stress of electrorheological fluids after particle polarized,expounds electrorheological fluids mechanical property,for the electrorheological fluids mount design establishes base.Following,the text introduces structures of old electrorheological fluids mounts,based on an inherent hydraulic pressure mount;works out a kind of electrorheological fluids mount structure with annular damping track,presents two-dimension and three-dimensional structure figure of the mount,specifies its principle of operation and working modes,analyzes flow of electrorheological fluids inside of the damping track.Then,the text summarily introduces bond graph approach,establishes bond graph model of the designed electrorheological fluids mount,writes its equation of state,and deduces computing formula of dynamic stiffness and loss angle of damping.introduce simulation theory of Matlab/Simulink,according to mathematical model of electrorheological fluids mount established relevant Simulink realistic model;presents primary simulation parameters,in different electric field intensity proceed simulation of mount system dynamic characteristics,after each primary structure parameter changed proceeds dynamic characteristics simulation.Simulation proven:with electric field intensity increased,peak value of electrorheological fluids mount dynamic stiffness and loss angle of damp obviously move to low-frequency stage,which could according to engine vibration frequency range,for mount system in low-frequency stage supply required large stiffness,large damping,effectively advance mount vibration isolation performance;in addition,increaseing damping track length and wanning damping track large diameter,which can make mount dynamic characteristics much more superiorior.Finally,summarily it introduces different kinds of controlling means,put forward to adopt fuzzy control strategy,expound fuzzy control detailedly,establishes two degrees of freedom semiactive control system model,presents each major parameter of the system,and utilizes Simulink to proceed simulation analyses of semiative mount vibration isolation performance.Proven,after applicated control,body displacement and speed caused by engine vibration is obviously less than not applicated control.Indicated,vibration isolation performance of the semiactive control electrorheological fluids mount distinctly excel the passive hydraulic mount.