Study On Mechanical Properties And Applications Of Magnetorheological Elastomer Film

Magnetorheological elastomer(MRE)film is a film-shaped MRE.which belongs to the category of smart materials.The traditional MRE is mainly prepared by mixing the common rubber matrix with ferromagnetic particles.It has the advantages of controllable stiffness,excellent mechanical properties,etc.It is often used in vibration.isolation,earthquake protection and other fields.In practical engineering applications,loading the MRE often produces a certain amount of prestress on the MRE.However,the performance of the MRE under prestress still remains mysterious.In addition,due to the large thickness,the stretchability and flexibility of traditional MRE are very poor,which is not conducive to the application of MRE in specific fields.Thus,researchers developed a new kind of MRE,named as MRE film,which has excellent stretchability,flexibility and magnetic controllability.For the first time,the whole field magnetization deformation of MRE film was systematically studied by experimental methods.The sound absorption performance of MRE film was deeply studied.An actuator based on MRE film was designed to explore the intelligent application of MRE film.The main research contents of this paper are as follows:1.The mechanical properties of MRE with different particle contents under prestressing were studied.A mechanism model of MRE under prestressing was proposed through theoretical derivation.With the increase of prestress,the zero field storage modulus,the magnetic induced storage modulus and the maximum storage modulus of MRE firstly increase to the maximum and then decrease to a relatively low value.In this process,the contact between the MRE and rheometer can be divided into three intervals,ie non-full contact,full contact and overload region.For the full contact zone,applying a prestress can change the particle spacing,thus changing the macro-mechanical properties of the MRE.In order to study the mechanical properties of MRE in the full contact zone,a mechanical model was proposed based on the theoretical derivation.This model is in good agreement with the experimental results.The model can be used to predict the mechanical properties of MRE in the fully contact zone.2.The digital image correlation(DIC)and Laser Doppler velocimetry(LDV)methods are used to systematically investigate the deformation characteristics of MRE film under free and fixed boundary conditions.It was found that the deformations of the MRE film at the free and fixed boundary conditions are crescent-shaped and bowl-shaped,respectively.When the magnetic field is removed,the MRE film can quickly return to the initial state.The DIC and LDV results are basically the same.When the currents are 1 A,2 A and 3 A,the maximum deformations are 0.10 mm.0.33 mm and 0.63 mm,respectively.The internal stress and internal strain of MRE film at 3 A current were roughly calculated by using finite element analysis method,and the maximum values are 33 kPa and 2.3%,respectively.The results show that the deformation of MRE film is within the elastic deformation range,and its deformation is stable and controllable.3.The MRE film-based sound absorbing structure(MRE film-SSS)was developed.The deformation characteristics of MRE film in MRE film-SSS were analyzed by DIC method,and the sound absorption performance of MRE film-SSS was further studied.Increasing the current will increase the deformation of the MRE film and the maximum sound absorption frequency of the MRE film-SSS.Increasing the CIP content can enhance the deformability of MRE film under a magnetic field,and the changeability of the maximum sound absorption frequency of MRE film-SSS under a magnetic field.In the absence of current,increasing the CIP content can effectively reduce the maximum sound absorption frequency of the MRE film-SSS.Reducing the thickness of the film can also enhance the changeability of the maximum sound absorption frequency of MRE film-SSS under a magnetic field.At the same time,the smaller the film thickness,the greater the maximum sound absorption frequency and coefficient of the MRE film-SSS.4.A new type of MRE film actuator was developed by using MRE film and PVDF film.The magnetic-mechanic-electric coupling performance of the MRE film actuator was systematically studied.A magnetic-mechanic-electric coupling model was established by theoretical derivation.An intelligent gripper based on MRE film actuator was designed.The MRE film actuator is very sensitive to amplitude and shows excellent repeatability.Experimental and theoretical studies show that the pure bending induced charge of the MRE film actuator is directly proportional to the deformation angle of the PVDF film.The intelligent gripper developed with MRE film actuator can grab,transport and release objects that are three times their own weight under the control of magnetic field,while the deformation of their antennae can be measured and feedback to the computer in real-time.