Study On The Mechanical Properties Of Magnetorheological Elastomer And Its Application In Tube Bulging

Piping parts occupy a very important position in various parts of aerospace equipment.In order to further meet the needs of lightweight,high-precision development of aerospace equipment,light alloy complex thin-walled hollow components have gained more and more attention.Such complex hollow components are often integrally formed by medium pressure forming process.At present,the most common pressure transmission medium used in medium pressure forming is water or oil and other liquids,which are usually called hydroforming.However,in the aerospace field,the demand for complex hollow components with large cross-sectional change ratios and large expansion rates is increasing,which brings huge technical challenges to the existing bulging process.On the one hand,because the forming force cannot be differentiated,it is easy to induce the risk of rupture;on the other hand,the high hydraulic pressure or air pressure increases the sealing problem of the system.In order to further improve the forming performance and precision quality of complex thin-wall hollow components,this paper proposes a tube bulging process based on magnetorheological elastomers,which uses the magnetorheological effect of magnetorheological elastomers to realize intelligent control of the tube bulging process.For the process,the process principle,the mechanical properties of the filling medium and the optimization of process parameters have been studied,providing theoretical guidance and technical support for other similar hollow components with complex curved surface features.Using smart material-magnetorheological elastomer to replace the traditional liquid medium,a new type of medium pressure forming process with magnetorheological elastomers was proposed,and its principle,the realization method of the differential control of the forming force,the preparation method of the magnetorheological elastomer and the key process parameters were analyzed,and the corresponding experimental test platform was built according to the experimental purpose.The mechanical properties of magnetorheological elastomers were systematically studied.Using a special experimental device designed and developed independently,the effects of magnetic particle concentration,magnetic flux density and deformation speed on the compression mechanical properties of magnetorheological elastomers were studied.The experimental results showed that the Poisson’s ratio of the magnetorheological elastomer is above 0.498;when the concentration of magnetic particles increases from 0 to 44.7%,the strain required to reach the transition stage gradually increases;when the magnetic flux density is 200 mT and the concentration of magnetic particles is at 11.9%,the bulk compressive modulus and Poisson’s ratio have the largest changes,which are 15.7%and 0.096%,respectively.For the target parts,a finite element model of magnetorheological elastomer pressure forming was established,the key parameters affecting the process were obtained through simulation,and the approximate value range of the process parameters was obtained through theoretical analysis.Combined with the response surface method,the response surface model between the maximum thinning rate and the average bulging diameter with the magnetic flux density and the axial feed of the punch was established,and the parameters were further optimized.The results showed that the maximum thinning rate of the target parts obtained under the currents of 0 A,3 A and 6 A are all less than 20%,and the increase of the current intensity will improve the filling degree of the pipe.Finally,relevant experiments were carried out to verify,using the best combination of process parameters,the current intensity was 6 A,the axial feed of the punch was 7.6 mm,and the target parts with excellent quality were finally obtained,and the maximum thinning rate was 18.85%.