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毕业论文网 > 毕业论文 > 理工学类 > 工程力学 > 正文

基于细观力学方法的各向同性磁流变弹性体非线性力学行为分析毕业论文

 2020-04-12 04:04  

摘 要

随着当代科技的迅猛发展,大批性能优越的智能复合材料不断涌现。目前,用于主动控制阻尼器和谐振器的智能复合材料主要为电磁流变类材料。作为磁流变材料中的一员,磁流变弹性体(Magnetorheological Elastomers, MREs)与更早出现的磁流变液材料相比,不仅继承了可控性、可逆性、响应迅速等高技术特征,还具有稳定性好、结构设计简单、制备成本低等独特的优点。

通常情况下磁流变弹性体在大荷载(外力与外磁场)作用下会发生明显的非线性行为。针对聚合物基复合材料非线性大变形行为分析,现有的理论分析方法通常可分为有细观力学方法和分子链网络模型两大类。鉴于复合材料的有效行为通常依赖于其局部微观结构和性能的平均响应,并不需要建立复杂的分子链网络模型,因此,细观方法在分析这类问题时显得格外有效。现有的经典细观力学模型已经普遍用来指导工程实践,但是由于该类理论基础是基于线弹性材料本构建立的,因此在复合材料非线性大变形行为分析时,需要经过合理的方法对其进行修正与拓展。

本文将针对以各向异性磁流变弹性体为代表的一类聚合物基颗粒增强复合材料,通过将基体非线性行为的多段线性化处理,在每一微小线性变形的过程中运用自洽方法,联合分析各向同性磁流变弹性体的非线性变形行为。文章关注磁流变弹性体中基体弹性性能对变形的依赖性,运用Neo-Hooken模型模拟基体的应力-应变曲线。通过数值模拟结果与现有实验和理论模型进行比较,说明本文所建立的数值力学模型的有效性与准确性。本研究的开展将会丰富磁流变弹性体基础行为的分析理论,为工程应用中磁流变弹性非线性变形行为予以理论指导。

关键词:各向同性磁流变弹性体,非线性,自洽方法,颗粒体积比。

Abstract

With the rapid development of contemporary science and technology, a large number of smart composite materials with superior performance continue to emerge. At present, the intelligent composite materials used for active control of dampers and resonators are mainly electromagnetic rheological materials. As a member of magnetorheological materials, Magnetorheological Elastomers (MREs) not only inherited controllability, reversibility, rapid response and other high-tech features compared with earlier magnetorheological fluid materials. , It also has unique advantages such as good stability, simple structure design and low preparation cost.

Under normal circumstances, the magnetorheological elastomer will undergo significant nonlinear large deformation behavior under the action of large loads (external and external magnetic fields). For the analysis of nonlinear large deformation behavior of polymer matrix composites, the existing theoretical analysis methods can be generally divided into two categories: meso-mechanics methods and molecular chain network models. Since the effective behavior of composite materials usually depends on the average response of their local microstructure and properties, and does not require the establishment of a complex molecular-chain network model, the micro-method is particularly effective in analyzing such problems. The existing classical micro-mechanical model has been widely used to guide engineering practice. However, since the theoretical basis of this kind of theory is based on linear elastic material, it is necessary to pass a reasonable method when analyzing the nonlinear large deformation behavior of composite materials. It is revised and expanded.

This article will focus on a class of polymer-based particle reinforced composites represented by anisotropic magnetorheological elastomers. Through the multi-stage linearization of the nonlinear behavior of the matrix, a self-consistent approach is used in each micro linear deformation process. Jointly Analysing the Nonlinear Deformation Behavior of Isotropic Magnetorheological Elastomers This article focuses on the dependence of the elastic properties of the matrix on the deformation of magneto-rheological elastomers, and uses the new-Hooken model to simulate the stress of the matrix. The comparison of the strain curve with the existing experimental and theoretical models by numerical simulation results shows that the numerical model established in this paper is valid and accurate. The development of this research will enrich the analytical theory of the basic behavior of magnetorheological elastomers and provide theoretical guidance for the nonlinear deformation behavior of magnetorheological elasticity in engineering applications.

Keywords ;Magnetorheological elastomers, Non-linear, Self-consistent method, Particle volume fraction

目录

第1章绪论 1

1.1研究背景 1

1.2研究现状 2

1.3研究意义 3

1.4本文工作 3

第2章 颗粒增强复合材料细观力学分析基础 5

2.1 颗粒增强复合材料中的弹性问题 5

2.1.1 颗粒增强复合材料弹性问题的一般解 5

2.1.2 材料弹性模量与刚度分量间的关系 7

2.2 颗粒增强复合材料弹性问题中经典细观力学方法 7

2.2.1 稀疏方法 8

2.2.2 Mori-Tanaka方法 9

2.2.2 自洽方法 10

第3章 各向同性磁流变弹性体非线性变形拉伸行为模拟 16

3.1 超弹性材料本构模型 16

3.2 细观力学方法在各向同性磁流变弹性非线性拉伸行为中的应用 19

3.3 结果分析及讨论 23

3.4本章小结 20

参考文献 21

致谢 23

第1章 绪论

1.1研究背景

复合材料材料的使用已有十分悠久的历史,在古代,人们使用麦秸与黏土的混合物来建造房屋,近代使用钢筋混凝土作为建筑材料,20世纪中期,人们尝试将玻璃纤维与塑料混合起来,制备了玻璃钢这种新型的复合材料,在此之后复合材料产业飞速发展,出现了碳纤维,石墨纤维,硼纤维,芳纶纤维等新型复合材料。人们在追求材料高强度高刚度的同时,对材料的功能性提出了要求,例如作为记忆金属代表的镍钛合金,作为战斗机实现隐形核心的隐身复合材料,另外还有具有感觉、处理和执行功能,能适应环境变化功能的机敏复合材料,仿生复合材料,仿生复合材料等等。随着各种新型复合材料的出现,如何了解它们的力学性能,研究基体材料,夹杂材料与合成之后的复合材料之间的关系,找到一种简便而且准确的复合材料研究办法也变的越来越重要起来。

近些年来随着当代科技的迅猛发展,大批性能优越的智能复合材料不断涌现。目前用于主动控制阻尼器和谐振器的智能复合材料主要为电磁流变类材料,其材料性能满足主动控制阻尼器和谐振器中对的刚度和阻尼改变、较快响应速率等的特殊要求。

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