聚氨酯及其碳纤维复合材料形状记忆行为有限元模拟及灵敏度分析

发布时间：2018-06-16 21:53

本文选题：有限元模拟 + 形状记忆高分子复合材料　；参考：《山东大学》2015年硕士论文

【摘要】：形状记忆材料是指具有形状记忆效应(SME)特性,即在受到光、电、热、磁等刺激之后可从临时形态回复到初始状态的一类材料。形状记忆高分子及其复合材料主要应用领域包括空间展开结构(铰链、桁架等)、变形机翼蒙皮、可折叠机翼、生物学仿生仪器、高分子纺织、生物自愈合体系等。其中,设计机构简单、变形效率高、成本低的智能变形结构具有十分重要的现实意义。实践证明,利用形状记忆效应可以显著提高结构的折叠率,并且减小折叠和展开时所需要的输出功,降低能源消耗和成本。从工程角度来看,形状记忆高分子及其复合材料性能比金属材料的更容易优化和改善,而且具有质轻、形变率高、响应速度快、经济合理的优点。开展相关领域的基础理论研究,将为形状记忆高分子及其复合材料的应用奠定基础,同时为我国智能飞行器的研究和发展提供技术储备,具有十分重要的意义。本文应用有限元模拟方法,结合高分子粘弹性理论、纤维增强树脂基复合材料力学理论建立三维有限元模型,对形状记忆高分子及其复合材料的形状记忆行为特点以及影响形状记忆行为的因素进行了模拟分析。研究内容和结果如下：(1)数值分析聚氨酯弯曲形状记忆过程,并讨论升温速率对形状记忆效应的影响。对预变形温度、预变形速率和预变形程度三个影响因素对形状记忆效应开展灵敏度分析。基于热力学和各向同性粘弹性力学以及高聚物结构与性能关系等理论基础,结合热膨胀理论,利用COMSOL Multiphysics 4.3a软件,实现了多物理场耦合,对聚氨酯弯曲形状记忆回复过程中应力、变形程度随温度的变化规律进行了分析,建立了高分子形状记忆过程中温度-应力-变形程度的关系曲线。并基于这一模型,讨论了形状记忆效应关于影响因素的灵敏度。结果表明形状回复率与升温速率关系较大,形状回复力主要受预变形程度影响。(2)数值分析连续纤维增强树脂基复合材料弯曲形状记忆过程,并讨论纤维含量对形状记忆效应的影响,开展了形状记忆效应影响因素的灵敏度分析。基于热力学、纤维增强复合材料力学和各向异性粘弹性力学等理论,建立了单向纤维增强树脂基复合材料形状记忆效应分析模型,结合COMSOL Multiphysics 3.5a软件,研究了单向纤维增强复合材料的弯曲形状记忆效应,建立了温度-预变形程度-应力之间的关系曲线,讨论了纤维含量对形状记忆效应的影响。结果发现纤维含量增加,最大回复力增大,形状固定率有所下降。利用该模型针对纤维复合材料形状记忆效应对影响因素的灵敏度开展了数值分析。结果表明形状回复率与升温速率关系较大,形状回复力主要受预变形程度影响。(3)测试环氧树脂体系形状记忆高分子性能,实验研究其形状记忆行为。对中航工业北京航空材料研究院提供的形状记忆环氧树脂进行了结构和性能分析,并通过DSC测试确定其玻璃化转变温度为76℃,通过应力松弛实验,探究其粘弹性性质。实验研究了环氧树脂形状记忆过程,分析了形状回复程度随着温度升高而变化的现象。
[Abstract]:Shape memory material is a type of material with the characteristics of shape memory effect (SME), that is, when stimulated by light, electrical, thermal, magnetic and other stimuli from temporary form to initial state. The main applications of shape memory polymers and their composites include space expansion (hinges, trusses, etc.), deformation wing skin, folding wing, and biology. Learning biomimetic instruments, polymer textile, biological self healing system, etc., which have a very important practical significance for the intelligent deformable structure with simple design mechanism, high deformation efficiency and low cost. It is proved that the folding rate can be greatly improved by the shape memory effect, and the output work needed when folding and unfolding is reduced, and the energy is reduced. Source consumption and cost. From the point of view of engineering, the properties of shape memory polymers and their composites are more easily optimized and improved than metal materials, and have the advantages of light quality, high deformation rate, fast response and reasonable economy. The basic theory research in related fields will be laid for the application of shape memory polymer and its composite materials. At the same time, it is of great significance to provide technical reserve for the research and development of China's smart aircraft. In this paper, a three-dimensional finite element model is established by using the finite element simulation method and the theory of polymer viscoelasticity and the mechanics theory of fiber reinforced resin matrix composite material. Shape memory polymer and its composite material are memorable. The characteristics of the behavior and the factors affecting the shape memory behavior are simulated. The contents and results are as follows: (1) the memory process of the bending shape of polyurethane is analyzed numerically, and the influence of the heating rate on the shape memory effect is discussed. The effect of the pre deformation temperature, the predeformation rate and the predeformation degree on the shape memory effect is opened. Based on the theoretical basis of thermodynamics and isotropic viscoelasticity and the relationship between the structure and properties of polymers, combined with the theory of thermal expansion and the COMSOL Multiphysics 4.3a software, the multi physical field coupling is realized, and the stress in the memory recovery process of the bending shape of the polyurethane is carried out with the variation of the deformation degree with the temperature. The relationship between temperature stress and deformation degree in the shape memory process of polymer was established. Based on this model, the sensitivity of shape memory effect on influence factors was discussed. The results showed that the shape recovery rate was closely related to the heating rate, and the shape recovery force was mainly influenced by the pre deformation degree. (2) the numerical analysis of continuous fiber was carried out. The effect of fiber content on shape memory effect is discussed and the sensitivity analysis of the influence factors of shape memory effect is discussed. Based on thermodynamics, fiber reinforced composites mechanics and anisotropic viscoelastic mechanics, a unidirectional fiber reinforced resin matrix composite shape has been established. The shape memory effect analysis model and the COMSOL Multiphysics 3.5A software were used to study the bending shape memory effect of the unidirectional fiber reinforced composite. The relationship curve between the temperature pre deformation degree and the stress was established, and the effect of fiber content on the shape memory effect was discussed. The results showed that the fiber content increased and the maximum recovery force increased. The shape fixing rate has been reduced. Numerical analysis is carried out on the sensitivity of the shape memory effect of fiber composites. The results show that the shape recovery rate has a great relationship with the heating rate, and the shape recovery force is mainly influenced by the pre deformation degree. (3) test the properties of the shape memory polymer of the ring oxygen resin system. The shape memory behavior of the shape memory resin was investigated. The structure and performance of the shape memory epoxy resin provided by Beijing Institute of Aerial Materials were analyzed. The glass transition temperature of the epoxy resin was determined by DSC. The viscoelastic properties of the epoxy resin were determined by the stress relaxation experiment. The shape memory process of the epoxy resin was studied and the shape of the epoxy resin was studied. The degree of recovery varies with the increase of temperature.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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