【作者】 高伟；

【导师】 王省哲；

【作者基本信息】 兰州大学 ， 力学·固体力学， 2018， 博士

【摘要】 作为近些年新兴的一类电磁智能材料,磁敏颗粒夹杂复合软材料具有非接触、远程、磁场可调控的力学与力磁耦合特性,特别是在外场作用下可产生快速、可逆、超大变形,使其在智能驱动与传感、主动减震降噪、仿生机器人等现代高新技术领域表现出诱人潜力和应用前景。由于该类复合材料的主要承载体是具有软物质特性的橡胶类高分子聚合物材料,其磁控力学响应与力磁耦合性能更易受夹杂相的磁学特性、微结构分布特征以及外加磁场、温度等环境因素的影响。深入探究与磁敏颗粒夹杂复合软材料基础力学性能相关联的主要影响因素与多场行为,是该类智能复合材料多场性能表征和揭示耦合行为机制的基础与核心课题。基于基础实验测试、理论与数值分析等手段与方法,本文较系统地制备并表征了不同组分比、不同磁性磁敏颗粒夹杂复合软材料与结构在均匀、非均匀磁场以及温度场下的基本性能。在此基础上,提出和设计了两类新型的磁敏颗粒夹杂复合软材料的智能微结构,并深入开展了多场下的耦合行为与特征研究。1、基于胶料、交联剂以及磁敏颗粒混合的制备工艺,成功制备了性能稳定的含有不同粒径羰基铁粉的复杂多相材料,开展了相关的力磁性能实验表征。进一步,将描述聚合物材料循环变形的本构关系推广应用于磁敏颗粒夹杂复合软材料在磁场下的加、卸载变形行为研究,较好地解释了加、卸载过程中的力磁行为。其次,针对不同磁学特性铁粉、钴粉混合的多相复合材料,分析了材料微结构、热稳定性等基本性能,并探讨了其力磁耦合性能。相关结果解释了夹杂相对材料性能的影响机制,并为充分发挥材料的特性及提高性能作出了可供参考的依据。2、针对外加非均匀磁场中的磁敏颗粒夹杂复合软材料,实验研究了梯度磁场分布对其准静态剪切性能和动态粘弹特性的影响规律。基于磁偶极子理论模型分析了材料力学行为的磁场依赖机制,进一步提出并发展了一种新的、简单、有效表征磁致粘弹力学特性的方法—轴向共振法。基于提高磁场利用效率和一体化设计思想,将线圈埋置于复合软材料内部用于产生局部高梯度磁场,制备了驱动与响应一体化的磁敏智能复合材料。测试结果表明:该系统具有双向驱动、高磁流变效应的显著性能,对于一些高效、微驱动与响应结构的设计与应用具有重要指导意义。3、磁敏颗粒夹杂复合软材料的主要组成部分往往具有温度敏感性。为此,基于研究组研制的低温力学多场测试系统,扩展了背景磁场和温控功能,开展了温度与磁场共同作用下复合材料多场性能和准静态剪切力学响应的实验研究。通过综合考虑磁场、温度对磁势能和应变能的影响,建立了一描述剪切变形模式下磁敏复合软材料多场行为的超弹性本构模型,含有较少材料参数且模型参数具有明确物理意义并可实验测得;模型的理论预测结果与实验吻合良好,实现了力-磁-热多场共同作用下磁敏颗粒夹杂复合软材料剪切行为的有效表征与预测。4、首次设计和研制了一种具有响应迅速、可逆大变形和多环境适应性的磁驱动花瓣状微结构。从实验和理论分析两个方面,开展了该智能柔性微结构在外磁场驱动下的力学响应和力磁耦合特征研究,测试并实现了该微结构不同液体环境中对不规则形状与软表面物块的抓取和搬运,可拓展应用于非接触、远程磁场驱动的柔性机械操纵平台。进一步,提出了一种磁驱动的柔性仿生鱼概念模型,建立了仿生鱼磁-流-固多场耦合行为的数值模型并进行了定量仿真研究,探讨了仿生鱼在外加磁场驱动下的运动模式与机制。相关结果可望为该类仿生器件在智能远场驱动、药物输送等领域的潜在应用提供理论指导。更多还原

【Abstract】 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.更多还原