Study On The Controllable Adhesion Mechanism And Performance Of Magnetorheological Elastomers

Dry adhesion and friction between solid surfaces are widely present in many industrial and scientific fields.Among them,the adjustable and controllable adhesion is becoming more and more important,especially in the design of bionic wall-climbing robots and intelligent manufacturing equipment.Many studies generally use traditional methods such as electromagnetic adsorption and vacuum adsorption to achieve basic adhesion effects,and have achieved certain results.However,the energy consumption is relatively high,the noise during operation is relatively large,the application scenarios are also limited,and how to realize intelligent,adjustable and controllable is also a difficult problem.At the same time,the use of external fields such as magnetic fields as control methods has become a hot concern and is gradually becoming a rising star in the field of intelligent controllable adhesion.Among them,magnetorheological elastomer(MRE)have also received extensive attention as smart materials,and it has been proven that various properties such as adhesion characteristics can quickly change correspondingly under magnetic field.This provides a new idea for solving the problem of adjustable and controllable adhesion and desorption.In this thesis,the MRE is used as the object,the internal performance is improved by adding graphene nanoplatelets(GNPs)and other methods.A biomimetic adhesion array structure is designed according to the fleshy ball foot pad of cotton aphid,and the model is optimized by finite element simulation analysis and physical observation experiment.Combined with the classical adhesion contact theory,the characteristics and mechanism of magnetic-controlled adhesion under the biomimetic structure are analyzed.And built the corresponding magnetic-controlled device and adhesion experiment platform,and implemented the experimental verification of the adhesion performance related parameter test.The specific research content and conclusions of this thesis are as follows:1.The research background and engineering significance of controllable adhesion mechanism and performance of MRE were described.Aiming at the problem of poor adhesion regulation in current intelligent adhesion technology,the research status of controllable adhesion and MRE was reviewed,and the shortcomings in adhesion research were explained.Finally,the research route and work content of this thesis were indicated.2.Because of the surface of the traditional MRE is not smooth,the elastic modulus is too high,and the magnetic-controlled performance is not excellent.It cannot be adjusted and controlled well.The traditional MRE was optimized by replacing ferromagnetic particles,optimizing the ratio of nano fillers,and improving related preparation processes.Then,performance tests and characterizations were performed on all comparative samples.3.The bionic adhesion surface structure was designed and analyzed based on MRE.First,starting from the analysis of the principle of cotton aphid meat ball foot pads,a bionic method was used to design a biomimetic adhesive micro-pillar array structure.The switch of adhesion and desorption is accomplished by the positive and reverse transformation of the magnetic field direction.At the same time,the entanglement and bending model of the micro-pillar array was constructed,and the length-diameter-distance ratio of the micropillar array was analyzed and optimized.The influence of long-diameter-distance ratio on adhesion and desorption performance was analyzed,which provides a theoretical basis for the subsequent derivation of the adhesion and desorption formula.4.The magnetic-controlled adhesion mechanism of the MRE was analyzed and obtained by the simulation and theoretical analysis,and the influence curve of multiple parameters is fitted.Through the finite element simulation and actual measurement system,the magnetic-controlled deformation effect of the micro-pillar array and the microscopic changes of the surface morphology were analyzed,and the reason for the microscopic changes were analyzed.The theoretical analysis of the MRE surface contact model was carried out,and the adhesion formula of the magnetic-controlled adhesion mechanism was obtained.The rationality of the optimization and design in the previous chapters can be determined based on this,and it can provide theoretical support for the verification experiment and intelligent adjustable and controllable in the following chapters.5.Based on the analysis in the previous chapters,the corresponding magneticcontrolled device and the adhesion effect experimental platform were designed and built.The adhesion test of samples under no magnetic field and diverse magnetic fields was completed,and the results of the effective data obtained were discussed.This provides important data support for intelligent adjustable and controllable adhesion and desorption effects,and verifies the adhesion mechanism in the previous chapter.The actual magneticcontrolled effect display and repeatability test provide experimental demonstration for the engineering application of the MRE with the surface structure of the cotton aphid foot pad.