环氧树脂混杂复合材料的阻尼性能研究

从本文研究的混杂复合材料阻尼特性的影响因素看,玻璃纤维和碳纤维混杂复合材料中两种纤维对阻尼性能和力学性能的作用和贡献是不同的。经GF/CF混杂后,复合材料的阻尼性能符合混合率,阻尼因子界于GF复合材料和CF复合材料的之间。另外,纤维zk强复合材料的模量变化和玻璃化转变温度受所加纤维的种类、含量和混杂效果的影响。     

SMA混杂复合材料单层的被动阻尼

由形状记忆合金纤维、普通纤维、基体构成的混杂复合材料是一类用途广泛的智能材料结构系统。阻尼性能研究是结构被动振动控制的一项重要研究内容。本文采用混杂复合材料阻尼预测的细观力学理论计算SMA纤维混杂复合材料单层的阻尼特性。首先计算包含普通纤维和基体材料的复合材料介质的阻尼性能,其次计算由横观各向同性介质和SMA纤维构成的混杂材料的阻尼性能。通过计算实例分析SMA纤维混杂复合材料单层的正轴阻尼特性及其偏轴阻尼的特性随SMA纤维体积含量、纤维铺设角等参数改变的规律。     

碳纤维/Kevlar纤维混杂复合材料的研究进展

纤维混杂复合材料作为一种先进的复合材料,受到国内外众多研究者的青睐。介绍了纤维混杂复合材料的发展,并描述了纤维的混杂方式。着重概述了碳纤维/Kevlar纤维混杂复合材料在拉伸性能,冲击性能,压缩性能,摩擦性能,吸湿性能,阻尼性能,热性能方面的研究进展。简要探讨了纤维走向、铺层方式、混杂比等对其性能的影响。     

填充MRE的纤维金属混杂复合材料梁阻尼减振性能研究

对填充磁流变弹性体芯层的纤维金属混杂复合材料梁减振特性开展试验研究。自主设计并制备具有磁流变弹性体芯层的纤维金属混杂复合材料梁,并首次在梁的内部施加磁场,探究磁场作用下复合梁的阻尼减振性能。设计磁场强度可控的复合梁振动测试系统,并详细介绍系统各个部件的组成和功能。然后归纳出一套合理、规范的不同磁场强度下该类型复合材料梁的振动测试流程,并进行实际测试。研究发现,该类型复合材料梁具有优异阻尼减振性能,前4阶阻尼比大于10%,且施加磁场作用后,还可进一步提升其阻尼,并达到主动控制阻尼性能的目的。     

湿热环境下玻/碳纤维混杂复合材料梁阻尼特性的细观力学分析

基于复合材料细观力学,利用能量耗散原理及宏观应变能法建立了湿热环境下玻/碳纤维混杂复合材料层合梁的阻尼预测模型。利用MATLAB软件编写了湿热环境下玻/碳纤维混杂复合材料损耗因子的计算程序,研究了纤维铺设角度、体积分数、铺层顺序以及湿热效应对玻/碳纤维混杂复合材料层合梁阻尼性能的影响规律。结果表明：湿热环境导致材料产生湿热应变是影响阻尼特性的主要机理;玻/碳纤维混杂复合材料层合梁的损耗因子均随温度及吸水浓度的增大而增大,且温度的影响远大于吸水浓度的影响;纤维体积分数越高,受湿热影响程度越大;铺层角度对损耗因子影响远高于湿热、混杂方式、纤维体积分数的影响。     

CF／GF多向混杂纤维复合材料拉伸特性研究

本文以碳纤维（ＣＦ）与玻璃纤维（ＧＦ）混杂，制成多向混杂纤维复合材料层板，并对其层板进行拉伸性能测试，观察其拉伸行为。同时在层板理论的基础上，考虑到混杂效应的作用，提出了多向混杂纤维复合材料非线性迭代强度估算模型。     

苎麻纤维布和玻璃纤维布混杂铺层复合材料的力学性能

利用真空吸注成型(vacuum resin absorbable molding,VRAM)工艺制备苎麻纤维布与玻璃纤维布混杂铺层的环氧树脂基复合材料。测定复合材料的损耗因子、储能模量的温度谱和力学性能;利用单悬臂梁共振实验测量复合材料的共振频率和自由振动衰减曲线并计算出了阻尼因子。用有限元软件对其共振频率和自由振动衰减实验进行仿真分析。结果表明:通过苎麻纤维布/玻璃纤维布的混杂铺层,能够实现材料阻尼性能和力学性能的可控调节,充分发挥复合材料可设计性强的优势。其中RGR铺层的复合材料的损耗因子比纯玻璃纤维板提高了1.4倍,而拉伸强度比纯苎麻纤维板提高了3倍多;自由振动的有限元模拟曲线和实验曲线基本吻合,表明可以通过模拟软件实现复合材料的虚拟振动测试,从而为材料性能预测和设计提供方便。     

混杂纤维复合材料最优纤维混杂比例及其应用研究进展

混杂纤维复合材料以其性能和低成本等优势近期取得了快速发展和应用。纤维混杂比例不仅影响构件的性能,同时关乎成本。本文介绍了混杂纤维复合材料的性能优势,分别对复合材料最佳性能和最佳成本时的纤维混杂比例的研究进展进行了综述,并介绍了混杂纤维复合材料的应用近况,提出了混杂纤维复合材料目前在发展中的不足,对其发展方向进行了展望。     

纤维混杂复合材料研究进展

介绍了近年来国内外纤维混杂复合材料的研究发展,从混杂比、混杂方式和界面三个方面分析了影响纤维混杂复合材料性能的因素,并介绍了纤维混杂复合材料在冲击性能、剪切性能、压缩性能、热性能、声学性能、透波性能方面的研究进展,并对我国纤维混杂复合材料今后研究提出相关建议.     

层间混杂复合材料装甲板防弹性能及其防弹机制

为研究层间混杂复合材料装甲板的防弹性能及其防弹机制,采用钢芯弹侵彻层间混杂复合材料装甲板。以超高分子量聚乙烯（Ultra high molecular weight polyethylene,UHMWPE）纤维、对位芳香族聚酰胺纤维作增强纤维,水性聚氨酯（Waterborne Polyurethane,WPU）树脂和环氧树脂（Epoxy resin,EP）作基体,采用热压工艺制备单向（Unidirectional,UD）结构的层间混杂复合材料装甲板。研究混杂比例、防弹面和树脂基体对混杂复合材料装甲板防弹性能的影响以及弹击后混杂复合材料装甲板的破坏形貌,分析混杂复合材料装甲板的防弹机制,并对复合材料装甲板的破坏机制进行了分析。结果表明:混杂复合材料装甲板的防弹性能优于其任一单一纤维复合材料装甲板;WPU的防弹性能要优于环氧树脂;以UHMWPE纤维复合材料充当防弹面时,混杂复合材料装甲板具有更好的防弹性能;纤维拉伸变形和装甲板分层是纤维复合材料装甲板主要的吸能方式。      

Development of the composite third robot arm of the six-axis articulated robot manipulator

The material used for robot structures should have specific stiffness (stiffness/density) to give positional accuracy and fast maneuverability to the robot manipulator. Also, high material damping is beneficial because it can dissipate the structural vibration induced in the robot manipulator structure. Both the high specific stiffness and damping of the material cannot be achieved through conventional materials such as steel and aluminum because they have almost the same low specific stiffness and low material damping. However, fiber reinforced polymeric composite materials that consist of high specific modulus fiber and high damping matrix have both high specific stiffness and high material damping.

In order to increase specific stiffness and damping, in this work, the third robot arm of the articulated robot manipulator that has 6 d.f. (degrees of freedom), 60 N payload and 0.1 mm positional accuracy of the end effector was designed and manufactured with carbon fiber epoxy composite material. The composite third robot arm was composed of the composite yoke, the composite cylindrical tubular structure and the aluminum flange.

After manufacturing the composite arm, the dynamic property and operational performance were compared to those of the hybrid third robot arm that was composed of the aluminum yoke, the composite tubular structure and the aluminum flange.

From the experiments, it was found that the composite third robot arm contributed to improving both the dynamic characteristics and operational performance of the articulated robot.     

Design of hybrid steel/composite circular plate cutting tool structures

Substituting composite structures for conventional metallic structures has many advantages because composite materials have both high specific stiffness and damping characteristics compared to conventional metallic materials. In this study, circular plate cutting tools which are used for rough machining of bearing sites in crankshafts or camshafts were designed with the fiber reinforced composite material to reduce tool mass and to improve the dynamic stiffness of circular plate cutting tools. The hybrid steel/composite circular plate cutting tool was analyzed by finite element method with respect to material types such as composite and foam, stacking angles of the composite, adhesive bonding thickness, and dimensions of the cutting tool. Also, the constrained damping characteristics of the tools were experimentally investigated with respect to the adhesive bonding thickness and material type such as composite and PVC foam. From the finite element analysis and experimental results, optimal design parameters for the hybrid steel/composite circular plate cutting tool were suggested.     

Experimental evaluation of dynamic behavior of metallic plates reinforced by polymer matrix composites

The applications of composite materials have become common in different industries. These materials introduce lower weight, high strength, and viscoelastic properties. Although composite materials offer many advantages in the designing and manufacturing of structures, they cannot replace the wide range of using metallic materials. Most of the industries especially aerospace try to use composite materials together with metal advantages in order to design a safe and optimized structure. The offshore structure can be reinforced and repaired with composite layers. In this research, the effects of composite reinforcement on the dynamic behavior of metallic plates are studied. Several panels are treated with different lay-ups and the modal testing was conducted to evaluate the effect of such treatments. This reinforcing can change both stiffness and damping properties of structures.

The stiffness properties of such reinforced plates can be influenced by fiber properties, while the damping properties come from the viscoelastic property of the matrix. Modal testing is applied to the specimens and the modal parameters are derived experimentally. This study shows that using composite material can modify both stiffness and damping characteristics.     

Novel applications of composite structures to robots, machine tools and automobiles

Mechanical design can be classified into stiffness design and strength design. In the stiffness design, the stiffness or deformation of members is concerned, and the enhancement of dynamic characteristics such as natural frequency or damping capacity of members or systems is also important. While, in the strength design, the primary concern is the enhancement of load carrying ability of members or systems.

Fiber reinforced composite materials offer a combination of strength and modulus that are either comparable to or better than many traditional metallic materials. Because of their low specific gravities, the strength-weight ratios, and modulus-weight ratios of these composite materials are much superior to those metallic materials. Composite materials can be tailored to meet the specific requirements of each particular design. Available design parameters are the choice of materials (fiber, matrix), the volume fraction of fiber and matrix, fabrication method, number of layers in a given direction, thickness of individual layers, type of layer (unidirectional or fabric), and the layer stacking sequence.

The greatest disadvantages of composite materials are the costs of the materials and the lack of well-defined design rules, therefore, composite materials should be applied in the right place with appropriate design rules. Up to now, the fiber reinforced composite structures are mainly employed in the strength design such as aircraft, spacecraft and vehicles.

In this paper, the novel application examples of composite structures to components for the robots, machine tools and automobiles are addressed considering the stiffness design issues of composite structures.     

Processing and hygrothermal effects on viscoelastic behavior of glass fiber/epoxy composites

Fiber reinforced epoxy composites are used in a wide variety of applications in the aerospace field. These materials have high specific moduli, high specific strength and their properties can be tailored to application requirements. In order to screening optimum materials behavior, the effects of external environments on the mechanical properties during usage must be clearly understood. The environmental action, such as high moisture concentration, high temperatures, corrosive fluids or ultraviolet radiation (UV), can affect the performance of advanced composites during service. These factors can limit the applications of composites by deteriorating the mechanical properties over a period of time. Properties determination is attributed to the chemical and/or physical damages caused in the polymer matrix, loss of adhesion of fiber/resin interface, and/or reduction of fiber strength and stiffness. The dynamic elastic properties are important characteristics of glass fiber reinforced composites (GRFC). They control the damping behavior of composite structures and are also an ideal tool for monitoring the development of GFRC’s mechanical properties during their processing or service. One of the most used tests is the vibration damping. In this work, the measurement consisted of recording the vibration decay of a rectangular plate excited by a controlled mechanism to identify the elastic and damping properties of the material under test. The frequency amplitude were measured by accelerometers and calculated by using a digital method. The present studies have been performed to explore relations between the dynamic mechanical properties, damping test and the influence of high moisture concentration of glass fiber reinforced composites (plain weave). The results show that the E’ decreased with the increase in the exposed time for glass fiber/epoxy composites specimens exposed at 80^∘C and 90% RH. The E’ values found were: 26.7, 26.7, 25.4, 24.7 and 24.7 GPa for 0, 15, 30, 45 and 60 days of exposure, respectively.     

DZ改性聚醚型聚氨酯阻尼材料的研究

通过动态力学热分析仪(DMA)和差示扫描热分析仪(DSC)研究了由聚氨酯(PU)与N,N-二环己基-2-苯并噻唑次磺酰胺(DZ)组成的混杂材料的阻尼性能.对PU/DZ混杂材料的DMA分析表明,DZ的加入使PU/DZ混杂材料的玻璃化转变温度升高,同时阻尼因子明显增大.DSC研究表明,PU/DZ混杂材料中的DZ有3种存在状态.DZ加入量的不同会对PU/DZ混杂材料的阻尼性能产生很大影响.     

Micromechanics and damping properties of composites integrating shear thickening fluids

Damping is an important parameter for vibration control, noise reduction, fatigue endurance or impact resistance of composite materials. In this study, a micromechanical model was used to predict the damping of a composite material containing shear thickening fluids (STFs) at the fibre–matrix interfaces. Predictions of the model and dynamical mechanical analysis results are in concert. The damping of the composites was improved significantly. The dynamic properties exhibited a strong dependence on both frequency and applied external load amplitude. Damping peaks appeared which coincided with the thickening of the STF at the fibre–matrix interface. The location of the peaks depends on the onset of thickening and post-thickening rheological behaviour of the STF. This work shows that a micromechanics approach can be useful for an appropriate choice of microstructural design and properties of STFs in order to control the stiffness and damping behaviour of composites. STFs can be integrated at the microscale of polymer composites to create new materials with load-controlled adaptive dynamic stiffness-damping properties.