纤维增强聚合物基复合材料老化研究进展

对于纤维增强聚合物基复合材料而言,湿热、光照等环境条件对其力学性能的影响明显,会导致其强度和刚度下降.本文阐述了国内外聚合物基复合材料的人工气候老化、湿热老化、热氧老化等方面的研究现状,人工加速老化和自然老化相关性方面的研究结果,聚合物基复合材料老化性能评定和寿命预测研究情况等.指出了纤维增强聚合物基复合材料老化研究存...     

纤维增强聚合物基复合材料低速冲击研究进展

综述了连续纤维增强聚合物基复合材料的低速冲击响应研究进展。讨论了测试方法及相关影响参数,例如冲头的形状、冲击速率对复合材料冲击的影响;介绍了冲击损伤的类型,进一步描述了层压板结构参数(如层合板厚度,铺层和缝纫)、复合材料组分材料性能(如纤维,树脂和纤维/树脂界面)以及预应力、环境条件等的影响;提出了纤维增强聚合物基复合材料冲击响应研究今后的发展方向。     

纤维增强Ti-Al金属间化合物基复合材料的发展

综述了纤维增强Ti-Al金属间化合物基复合材料的研究进展.介绍了Ti-Al金属间化合物基体的结构和性能、增强体纤维的运用、界面相容性对复合材料机械性能的影响、界面反应的动力学和热力学研究、以及目前Ti-Al金属间化合物基复合材料的最新制备技术.指出了今后纤维增强Ti-Al金属间化合物基复合材料的研究重点和发展方向.     

椰衣纤维资源化利用现状及其发展前景

目的 为了解决椰糠造成聚合物间界面相容性差,椰衣纤维作为增强体提升聚合物基复合材料力学性能弱的问题。方法 探究酸碱处理、偶联剂处理、接枝共聚处理等化学改性预处理方法对椰衣纤维与聚合物间的界面相容性、分散性、组分间粘附力等方面的影响,以及增强椰衣纤维复合材料的重要性,以此提高椰衣纤维缓冲包装材料的力学性能。结论 椰衣纤维作为椰子加工副产物,具有强度高、韧性强、防潮防腐、防虫蛀、透气性能良好等优点,针对其生物学特性进行高效合理改性,不仅提升了椰衣纤维的利用价值,而且还可作为增强体为聚合物基复合材料力学性能的增强提供更多的选择,进而为实现椰衣纤维植物资源高值化利用提供坚实的理论基础。与此同时,展望了椰衣纤维制备生物基纳米复合材料的应用前景,挖掘椰衣纤维在现代包装领域的潜在价值。     

纤维增强聚合物基复合材料的低温性能

对纤维增强聚合物基复合材料在低温领域的实际应用进行了分类介绍,通过对纤维增强聚合物基复合材料的低温性能、性能影响因素和作用机理、低温应用安全性等方面的研究工作进行总结,突出各类纤维增强聚合物基复合材料低温下的性能优势,阐明了材料性能的不足之处及相应改进措施.对于实际低温应用中纤维增强聚合物基复合材料的选择、性能设计优化,系统安全性的增强提供了参考作用.     

阻燃及防火纤维增强复合物的研究进展（英文）

聚合物基的纤维增强复合材料,热固性聚合物或热塑性聚合物基体,可通过随机或者编织的纤维来提高其弯曲和抗拉强度,此类复合材料作为轻量级、结构材料正越来越多地被应用于民用和交通运输等领域,该应用领域绝大部分要求材料应该具有防火性能。但大多数热固性聚合物、热塑性聚合物及一些增强纤维存在耐燃性差的问题。聚合物基的纤维增强复合材料的防火性能可以通过一系列方法进行提高,比如向聚合物基体添加含有促成炭组分等各类阻燃剂,但是最简洁有效的方法是在复合材料表面使用防火材料涂层或者使用表面防火保护膜。文章综述了英国博尔顿大学防火材料研究团队在阻燃以及防火纤维增强复合材料方面的研究工作。本文主要关注了阻燃添加剂和涂层对纤维增强的不饱和聚酯、乙烯基树脂和环氧树脂复合材料的影响。     

钛基复合材料及其制备技术研究进展

综述了钛基复合材料及其制备技术,重点介绍了纤维增强钛基复合材料(FTMCs)和颗粒增强钛基复合材料(PTMCs)的制备技术,分析了各种制备技术的优缺点.研究表明:纤维涂层法具有纤维分布均匀,纤维与界面反应小,复合材料性能优异等优点,是一种很有前景的FTMCs的制备技术.原位合成工艺制备的PTMCs避免了界面反应,界面清洁、结合强度高,可以明显提高PTMCs的力学性能.     

纤维增强聚合物基复合材料的界面性能

针对纤维增强聚合物基复合材料的界面性能，系统阐述了其界面层的结构和作用机理，详细介绍了界面结晶效应对力学性能的影响及界面性能的表征方法，最后论述了几种有效的纤维表面改性方法及改性效果。     

PVA短纤维和粉煤灰对地聚合物基复合材料流变学行为和弯曲性能的影响

利用自行研制的活塞式挤压流变仪研究了掺加聚乙烯醇(PVA)短纤维和粉煤灰的地聚合物浆体在挤压过程中的流变学特性,在此基础上通过单轴挤压机成功制备出宽厚比=12.5∶1.0的短纤维增强地聚合物基复合材料。利用MTS电液侍服机系统研究了各种纤维和粉煤灰掺量的地聚合物基复合材料的弯曲行为。采用扫描电镜(SEM)研究了地聚合物基复合材料中纤维的分布、取向、纤维-基体间界面,以及弯曲实验后试样断裂面上的纤维伸出长度、纤维尖端断裂形貌和纤维表面组织,从细观和微观角度探讨各种地聚合物基复合材料微观结构和弯曲破坏机制。结果表明：PVA短纤维的加入改变了地聚合物浆体的破坏模式,由脆性破坏变为延性破坏;对于不掺或掺加少量粉煤灰(≤10%)的地聚合物基复合材料弯曲强度高,但延性小,当粉煤灰的掺加量≥30%时,地聚合物基复合材料的弯曲强度显著下降,但延性增大。     

连续纤维增强陶瓷基复合材料概述

八十年代以来 ,连续纤维增强陶瓷基复合材料以其优异的性能特别是高韧性 ,得到世界各国的极大关注和高度重视 ,并取得令人瞩目的发展。纤维增强陶瓷基复合材料已开始在航空、航天、国防等领域得到应用。本文从复合材料的增韧机制、制备方法、界面特性和界面改性以及应用等方面综述了国内外有关连续纤维增强陶瓷基复合材料的研究现状     

原子力显微镜表征纤维增强聚合物复合材料的界面相概述

纤维增强聚合物复合材料(FRPC)的界面相是一个尺度只有几十纳米到几微米之间的微小区域,是复合材料中应力传递的枢纽,对复合材料的整体性能起着至关重要的作用。因此,急需寻求一种高分辨率的纳米探测技术来表征该区域并研究其性能,这对复合材料的结构设计有着重要的科学意义和指导作用。文章概述了几种原子力显微镜(AFM)常见应用模式,并且阐述了采用AFM表征FRPC界面相的研究现状,总结了目前存在的问题并提出未来的研究方向。     

Delamination detection in laminated composite beams using the empirical mode decomposition energy damage index

Fiber reinforced plastic composite (FRPC) beams have been widely used as effective stand-alone structural elements and/or reinforcing agents in various engineering applications. Such lightweight, stiff and strong structural elements may suffer, however, from inter-ply defects (referred to as delaminations), arising from various causes and factors. A delamination in such structural components could propagate into severely large damage zone, thus compromising the structural integrity. Therefore, detection of delamination at an early stage is of paramount importance.     

XFEM fracture analysis of cracked pipeline with and without FRP composite repairs

Abstract

The effect of fiber reinforced polymer composite (FRPC) repair on crack propagation in thin-walled steel pipes is examined. The extended finite element method is used in this study to simulate a pressurized cylindrical pipe with longitudinal crack in two conditions: the original cracked pipe and the pipe repaired with a composite patch. Carbon/epoxy or E-glass/epoxy FRP in two different fiber orientations are assumed for cracked pipe repair. Performance of four types of FRP repair systems are investigated by CTOA, COD and COA fracture criteria for both the pipe integrity assessment and the potential age of leak before break criterion.     

The influence of the interphase and associated interfaces on the deflection of matrix cracks in ceramic matrix composites

A model is proposed to determine the influence of an interphase on the deflection of a matrix crack in ceramic matrix composites. Then, a finite element analysis is performed for a microcomposite geometry with an annular crack which initiates in the matrix and propagates in the interphase. It is applied to a SiC/C/SiC microcomposite with a pyrocarbon interphase. Criteria for penetration and deflection of the matrix crack are expressed in terms of toughness of the interphase and of the various interfaces (matrix/interphase and interphase/fibre interfaces). The predictions are found to agree with crack deflections observed in practical SiC/SiC composites and with the available interphase toughness data. Results also suggest that the real crack deflection mechanism involves debonding ahead of the propagating matrix crack.     

A micromechanical characterization of graphite-fiber/epoxy composites containing a heterogeneous interphase region

An improved micromechanical model based on the method of cells is introduced in order to describe three-phase, continuous-fiber composite materials containing a heterogeneous interphase region. The model's capability represents a significant improvement over that of the previous version (which is applicable to a homogeneous interphase) in that additional microstress information is obtained within the interphase region. A critical assessment of the model demonstrates that the predictions are consistent with data reproduced by using other micromechanical models. The study includes a parametric simulation in which the effective properties and the mechanical stresses associated with model graphite-fiber/epoxy composites are predicted as a function of the dimensions and Young's modulus of the interphase. Three different interphases are modeled such that the Young's modulus varies between that of the fiber and the matrix according to a generalized parabolic function of the radial coordinate. The parabolic functions are specified such that two of the model composites possess an interphase whose effective Young's modulus is above that of the matrix. The third interphase is specified such that its effective Young's modulus is below that of the matrix. The data indicate that the interphase dimensions and the functional form describing the interphase Young's modulus significantly influence the composite microstresses. These data may be used to help identify optimum material combinations during composite material synthesis.     

The effect of the interphase and material properties on load transfer in fibre composites

An interphase between a fibre and a matrix is modelled with its own mechanical properties to study the load transfer through this crucial region. The effect of material properties on the maximum shear stress during the load transfer is investigated. The results indicate an optimum point where the shear stress would be the lowest at the interphase. With the help of this model, the effect of crack initiation at the interphase on the stresses is illustrated. It is shown that cracks are likely to initiate at the fibre/interphase interface rather than at the interphase/matrix side.     

陶瓷基复合材料多层界面相应力传递的有限元模拟

针对陶瓷基复合材料（CMCs）多层界面相的应力传递进行了有限元模拟。采用圆柱单胞模型描述CMCs的细观结构,按相应界面相亚层的实际厚度建立明确的界面相,并假设界面相亚层之间及界面相与纤维、基体之间初始完好结合,然后赋予各界面相亚层不同的材料参数,并采用轴对称有限元法进行求解,最终建立了多层界面应力传递的模拟方法。分别对比了不同厚度热解碳（PyC）界面相、PyC和SiC两种不同成分界面相及（PyC/SiC）和（SiC/PyC）两种结构界面相的应力传递模拟结果。从剪应力沿纤维方向分布及径向分布特点可以看出,通过合理配置CMCs内部多层界面相的结构、成分和厚度,可以实现界面相应力传递及失效模式的控制和优化。     

Effect of an interphase layer on the dynamic stress concentration in a Mg-matrix surrounding a SiC-particle

The potential of using an interphase layer to reduce stress concentrations under a dynamic loading in a Mg-matrix surrounding a SiC-particle is investigated in this study. An interphase layer was applied between the particle and the matrix and the contact between them was assumed to be perfect. Both constant-property materials and functionally graded materials were considered for the interphase. A constant-property interphase was modelled as a single layer while a functionally graded interphase was divided into a number of sublayers and each sublayer was treated as having constant material properties. Numerical results reveal that the interphase layer made of a constant-property material shows better stress concentration reduction than that made of functionally graded materials. An interphase layer with low values of both shear modulus and Poisson’s ratio is necessary for a significant stress concentration reduction. Studies were focused on determining the maximum stress concentration that occurs over a range of frequencies. This investigation has revealed that a stress concentration reduction of up to 44% could be realized.     

Simulation of interphase percolation and gradients in polymer nanocomposites

Experimental data suggests that well dispersed nanoparticles within a polymer matrix induce a significant interphase zone of altered polymer mobility surrounding each nanoparticle, which can lead to a percolating interphase network inside of the composite. To investigate this concept and the nature of the interphase, a two-dimensional finite element model is developed to study the impact of interphase zones on the overall properties of the composite. Thirty non-overlapping identical circular inclusions are randomly distributed in the matrix with layers of interphase surrounding the inclusions. The simulation results clearly show that the loss moduli of composites are either broadened or shifted corresponding to the absence or presence of a geometrically percolating interphase network. Our numerical study correlates well with experimental data showing broadening of loss peaks for unfunctionalized composites and a large shift of the loss modulus for functionalized nanotube polymer composites. Further, our results indicate the existence of a gradient in properties of the interphase layer and that incorporating this gradient into modeling is critical to reflect the behavior of polymer nanocomposites.     

Effect of an interphase region on debonding of a CNT reinforced polymer composite

The effect on stiffness and debonding of an interphase zone of altered polymer properties surrounding each carbon nanotube (CNT) in a CNT reinforced polymer composite is investigated. The interphase zone has position dependent material properties that merge with those of the polymer at a sufficiently large distance from the inclusion. There is evidence that such an interphase zone must be included in models in order to represent the overall composite properties. The analyses are based on an axisymmetric unit cell model of the composite. An elastic–viscoplastic conventional continuum constitutive relation (a size-independent relation between stress, strain and strain rate) is taken to characterize the bulk polymer material and the interphase, with the material properties being position dependent in the interphase. The interface between the polymer and the CNT is modeled by a phenomenological cohesive relation that allows for complete separation and the creation of new free surface. The effect of varying interface strength on the composite stress–strain response and on debonding is analyzed both with and without an interphase. The presence of an interphase increases the composite stiffness but promotes debonding which ultimately reduces composite stress carrying capacity. The compliance of the interface also affects the stress–strain response prior to debonding and leads to stress redistributions within both the fiber and the matrix (and/or interphase) which can affect the fracture mode that occurs.