Experimental Investigation Of Multi-Field Characteristics And Coupling Behaviors Of Magnetoactive Particles Filled Soft Composite And Structure

As a new kind of electromagnetic intelligent materials in recent years,magnetoactive particles filled soft composites(MPFSCs)have marvelous advantages of contactless,magnetic controlled mechanical properties and magneto-mechanical coupling characteristics.Especially,they can produce rapid and reversible huge deformation in the presence of magnetic field.These characteristics make MPFSCs exhibit an attractive developmental potential and broad applications prospect in many fields,such as intelligent actuation and sensing,active shock absorption and noise reduction,bionic structures and other modern technology.The main carrier of this novel kind of composites is rubber-like polymer material with a typical feature of soft matter,whose mechanical responses and multi-field coupling performances are more sensitive to the inclusion,the micro-structure features and the influence of external environmental factors such as the magnetic field,temperature,etc.Therefore,to deeply explore the main impacts that influence the basic mechanical property of MPFSCs and the behaviors of multi-field coupling are the foundation and core subject for characterizing the coupling performances of this kind of intelligent composites and revealing its mechanism of multi-field coupling behaviors.With various methods of experimental testing,theory and numerical analysis,this dissertation systematically prepared and characterized the basic performance of composite materials and structures reinforced with different combinations of carbonyl iron or magneto-sensitive particles with different magnetic characteristic in different environments,including homogeneous,inhomogeneous magnetic field and temperature condiction.On this foundation,two kinds of novel smart structures based on MPFSCs were proposed and designed.Meanwhile,the multi-field coupling behaviors and characteristics of these styles of intelligent structures were conducted.1.Based on the preparation techniques of mixing the crude rubber,cross-linking agent and magnetic particles,we successfully prepared a series of complicated multiphase materials reinforced with different particle size of carbonyl iron in our laboratory,which has stable performance.The related magneto-mechanical coupling behavior of MPFSCs was evaluated systematacially through experiment study.Furthermore,the constitutive relationship for cycle deformation of polymer material was extended and used for revealing behaviors of MPFSCs under a magnetic field environment.Some qualitative theoretical results are in good agreement with the experiment observations.Secondly,considering a series of MPFSCs with a mixture of carbonyl iron and cobalt particles at a given weight amount,the microstructure,thermal stability,magneto-mechanical coupling properties and magnetic actuating performance were studied experimentally.The relevant results explain the influence mechanism of inclusions on the material properties,and provide reference for making full use of the characteristics of the materials and improving the performance.2.In view of MPFSCs in a non-uniform magnetic field environment,the effect of gradient field distribution on the quasi-static shear performance and dynamic viscoelastic properties was investigated experimentally.Based on the traditional magnetic dipolar model,a reasonable explanation was proposed to qualitatively elucidate the magnetoelastic shear performance of this kind of magnetic smart composites.A new method to characterize the magneto-induced viscoelastic properties was further developed based on the resonant bar technique.To improve the application efficiency of the magnetic field and the integration of design ideas,a new composite structure embedded with two copper coils was designed to induce a strong local gradient field inside,which forms an integrated system of actuating device and sensitive materials.Experimental observations showed that the system has significant performance such as bidirectional drive,high magnetorheological effect and so on.It will provide important guidance for further design and application for the high-efficiency,micro-actuation and response structures.3.Since the main components of MPFSCs will unavoidably be influenced by environmental temperature,the steady shear behavior and multi-coupling properties of composite materials filled with different volume fraction of magnetic particles were investigated experimentally under the action of different temperature and magnetic fields.Taking into account the influence of magnetic field and temperature on the magnetic potential energy and strain energy,an improved superelasticity constitutive relation was developed for the magneto-thermo-elastic performance of MPFSCs in a pure shear deformation.The model was characterized with a few material and modeling parameters which always have specific physical meanings and can be determined experimentally.Comparisons between the theoretical predictions and experimental results were performed and demonstrated a good agreement on the steady shear features in the presence of temperature and magnetic fields.4.Inspired by the natural phenomenon of flowers expanding and closing movements under the action of light,a robotic platform with attractive properties of soft,rapid response,reversible and multiple-environment-adaptive,was first designed and fabricated by virtue of MPFSCs.The mechanical responses and magneto-mechanical coupling properties of this intelligent flexible soft structure were investigated experimentally and theoretically.Experiments demonstrated that the flexible platform in various shapes,that is,flowerlike shapes,can transport a cargo to targeted area in air and a variety of liquids.The results may be helpful in developing a magneto-driven carrying micro platform,which can be operated like a human finger to manipulate biological objects such as single cells,microbeads,or embryos.Further,a conceptual design and model based on the MPFSCs was proposed,and the numerical research of magneto-fluid-solid coupling behaviors for magnetic driving soft biomimetic robot fish was carried out.The motion mechanism of the bionic fish in the presence of an external magnetic field was discussed.The results may provide guidance and experience for the potential applications in intelligent remote field drive,drug delivery and other fields of the bionic devices.