Structural degradation and mechanical fracture of hybrid fabric reinforced composites

This investigation involves the study of accelerated environmental aging in two polymer composite laminates reinforced by hybrid fabrics based on carbon, Kevlar and glass fibers. Composite laminate configurations are defined as a laminate reinforced with E‐glass fiber and Kevlar 49 fiber hybrid fabric (GK) and another laminate reinforced with E‐glass fiber and AS4 carbon fiber hybrid fabric (GC). Both laminates were impregnated with epoxy vinyl ester thermosetting resin (Derakane 470‐300) consisting of four layers. Morphological studies (photo‐oxidation process and structural degradation) of environmental aging were conducted, in addition to comparative studies of the mechanical properties and fracture characteristics under the action of uniaxial tensile and three‐point bending tests in specimens in the original and aged conditions. With respect to uniaxial tensile tests for both laminates, good mechanical performance and little final damage (small loss of properties) was caused by the aging effect. However, for the three‐point bending tests, for both laminates, the influence of aging was slightly higher for all parameters studied. The low structural deterioration in the laminates is attributed to the high performance with the heat of the matrix (Derakane 470‐300) and the characteristics of the hybrid fabric, exhibiting fiber/matrix interface quality. POLYM. ENG. SCI., 56:657–668, 2016. © 2016 Society of Plastics Engineers     

Mechanical behavior and fracture toughness characterization of high strength fiber reinforced polymer textile composites

The mechanical and fracture behavior of polymer composites are the subject of great interest from many years and still interesting among the researchers. Composites are extremely used for their superior mechanical, thermal and fracture toughness properties in various sectors such as automobile, aerospace and defense applications. In this article, unidirectional and woven high strength glass, carbon and Kevlar fiber reinforced polymer textile composites are taken into consideration for the comprehensive review of mechanical behavior and fracture toughness characterization. Current review work began with the introduction to polymer textile composites with its manufacturing stages, processing techniques and factors affecting the performance under mechanical loading. The mechanical behavior of high strength fiber reinforced polymer (HSFRP) textile composites was discussed in tension, compression, flexural, low velocity and high velocity impact loading with the recent numerical and experimental characterization studies. Textile geometrical modeling and CAE tools are also described for numerical characterization. Under the influence of mechanical loading on composites, failure occurs actually due to the crack initiation and propagation, so it is also required to characterize. Significant elements of fracture mechanics are well described for the better understanding of fracture toughness characterization. Mode-I, Mode-II, Mode-III interlaminar and Mode-I intralaminar fracture toughness characterization are widely explained by considering the effect of filler content, fiber orientation and fiber volume fraction. Fracture toughness characterization techniques and research summery are uniquely presented by considering various factors under one umbrella for better understanding of fracture behavior. Statistical Weibull distribution is also presented for the failure prediction of composites.

     

Nonlinear tensile behavior of cotton fabric reinforced polypropylene composites

From the perspectives of elastoplasticity (nontime-dependent) and viscoelasticity (time-dependent), the Ramberg–Osgood relation and time-varying viscosity Maxwell (TVM) models were used to model and analyze the stress–strain behavior of cotton fabric-reinforced polypropylene composites (CFRLs), respectively. The Ramberg–Osgood relation could well describe the tensile behavior of CFRLs as an elastoplastic behavior, while the tensile behavior could also be described as a nonlinear viscoelasticity behavior by Maxwell model. The fitting results showed that the Maxwell model accurately described the tensile behavior of different CFRLs samples under low strain, but there was a considerable gap between the test data and model values when the strain was greater than 5%. Therefore, a time-varying viscosity fluid damper was used instead of a Newtonian fluid damper to modify the Maxwell model, namely the TVM model. The TVM model closely described the stress–strain behavior during the entire tensile process.     

Mixed-mode fracture behavior of glass fiber reinforced polymer concrete

Fracture toughness of chopped strand glass fiber reinforced particle-filled polymer composite beams was investigated in Mode I and Mode III loading conditions using three-point bend tests. Effects of crack angles on fracture behavior were also studied. The specimens, which have inclined crack at an angle θ to the axis of the specimens, were used to carry out the tests. The specimens were tested with inclination angles 30°, 45°, 60° and 75°. The results are compared with the values of K_IC obtained using conventional (θ=90° ) specimens. In addition, J integrals were also determined. J_IC increases continuously with increasing in crack angle from θ=30° to θ=90°. In contrast, J_IIIC decreases with the crack inclination angle θ from 30° to 90°.     

Interlaminar fracture toughness of selectively stitched thick carbon fibre reinforced polymer fabric composite laminates

Abstract

Carbon fibre reinforced polymer fabric specimens prepared from selectively stitched thick laminates have been tested under mode I (tension) and mode II (shear) loading, similar to already established tests used for thin unidirectional specimens. The respective interlaminar fracture toughness characteristics were derived for laminates of different stitching configurations. Results indicated significant interlaminar fracture toughness increase for all stitched samples compared with non-stitched samples, especially under mode I loading. It was concluded from parametric investigations that carbon thread stitching is more effective than its aramid counterpart in improving interlaminar fracture toughness. This is attributable to its higher stiffness and better bonding to the carbon fibre reinforced polymer system compared with the aramid thread.     

Erosive wear behavior and dynamic mechanical analysis of textile material reinforced polymer composites

The present analysis intends to look into the needlepunched nonwoven textile material reinforced polymer composites. The solid particle erosion wear behavior of needlepunched nonwoven fabric mat reinforced epoxy composites were assessed using silica sand particles with the size of 250, 350, and 450 μm. Taguchi analysis was also carried out on the basis of design of experiments (DoE) approach to establish the interdependence of operating parameters. Mechanical and physical properties of composites were also evaluated experimentally, and the storage modulus (E′), loss modulus (E″) and damping factor (tan δ) characteristics were analyzed with the help of dynamic mechanical analyzer (DMA) in the temperature range of 20–200°C. Surface morphology of the eroded surfaces of composites were also analyze by scanning electron microscopic (SEM) to discuss the feasible erosion mechanism on composite surfaces. The result reveals that fiber content and impact velocity has an invulnerable impact on the erosion rate of needlepunched nonwoven fabric mat‐epoxy composites. The mechanical and physical properties are meliorating with incorporation of fabric mat weight percentage in composites, and the measured damping factor (tan δ) peaks of T _g for needlepunched nonwoven fabric mat epoxy composites ranged from 100 to 110°C. POLYM. COMPOS., 38:2201–2211, 2017. © 2015 Society of Plastics Engineers     

Investigations of the tribological properties of carbon fabric reinforced phenolic polymer composites filled with several nanoparticles

The carbon fabric composites filled with several nanoparticles were prepared by dip‐coating and hot press molding technique. The friction and wear behavior of the resulting composites were studied systematically using a block‐on‐ring arrangement. Experimental results showed that the optimal content of nanoparticles as fillers contributed to improve the tribological properties of the carbon fabric composites. Moreover, the friction and wear properties of the fabric composites were closely dependent with the sliding conditions. The differences in the transfer film formed on the counterpart surface during the friction process also accounted for the friction and wear behavior of carbon fabric composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The effect of loading rate on the fracture toughness of fiber reinforced polymer composites

This article is a detailed review of the strain rate dependence of fracture toughness properties in polymer composite materials. An attempt is made to draw together all the strain rate studies done in the past and to elucidate the reasons given by the authors of the reviewed papers for the trends resulting from their studies to better understand the strain rate effects on the fracture toughness of fiber reinforced polymer composite materials. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 899–904, 2005     

Fracture behavior of short fiber reinforced thermoplastics I. Crack propagation mode and fracture toughness

The fracture behavior of several short glass fiber reinforced thermoplastics has been studied. The fracture toughness of these materials may be related to local crack propagation mode, which is found to be highly rate dependent. At low test rates the crack growth in the reinforced polymers tend to follow a fiber avoidance mode, creating a greater area of new surfaces, which in conjunction with greater degree of interfacial debonding and fiber pullout friction leads to a higher fracture resistance. An increase in loading rate in general results in a more straight and flat crack path, as well as a lesser extent of fiber debonding and pullout. Therefore the fracture toughness is reduced although the frequency of fiber breakage is increased. The fracture behavior of these short fiber reinforced polymers appears to be dictated by the matrix properties when the loading rate is high.     

Influence of pyrolysis temperature on fracture response in SiOC based composites reinforced by basalt woven fabric

The fracture resistance of ceramic based composites reinforced by various ceramic fibres can be dramatically enhanced when an efficient fracture mechanism takes place during the crack propagation. Presented work shows an effect of the pyrolysis temperature of the composite matrix on the fracture behaviour of the composite. The matrix is formed from the polysiloxane resin precursor and the reinforcement is a basalt woven fabric. The temperature range under investigation was from 600 °C, where the onset of fracture properties were observed up to 800 °C. Above this temperature basalt fibres suffer by rapid degradation of the microstructure. The optimum stage of the polysiloxane resin transformation maximizing the fracture resistance of the composite was identified. The fractographic analysis of the fracture surfaces revealed the differences in the acting fracture mechanism.     

晶须增强聚合物及硫酸钙晶须／聚合物复合材料

总结了晶须增强聚合物的优势,并指出了晶须增强聚合物在性能、工艺和价格上存在的问题。对晶须增强聚合物的发展提出了建议。介绍了价廉质优并已国产化的ＣａＳＯ４晶须的性能以及ＣａＳＯ４晶须在聚合物中的应用。     

Effects of carbon nanofiller functionalization and distribution on interlaminar fracture toughness of multi-scale reinforced polymer composites

Carbon nanofillers with different surface functional groups and aspect ratios, including carboxyl carbon nanotubes, un-functionalized carbon nanofibers (CNFs), glycidyloxypropyl-trimethoxysilane carbon nanotubes (GPS-CNTs) and nanofibers were evaluated for their potential for increasing the interlaminar fracture toughness of an S2-glass fiber/epoxy composite. The fillers were added in the matrix of the fiber reinforced plies, in the resin interlayer between plies, or in both regions. Comparisons were made based on mode I and mode II interlaminar fracture toughness. For composites made with CNTs dispersed in the matrix, fracture toughness was largely unaffected except for a slight increase seen with long GPS-CNTs. However, adding a CNF or CNT modified resin interlayer significantly increased the fracture toughness, with the highest improvement over the baseline material achieved by adding long GPS-CNTs in the interlayer (79% and 91% for mode I and mode II onset toughness, respectively). Important material parameters identified for improving interlaminar fracture toughness are the nanofiller aspect ratio and concentration at the fracture plane. Based on microscopic evaluations of the fracture surfaces, a high density of high aspect ratio nanofillers causes the best entanglement between the filler and glass fibers and effectively obstructs interlaminar crack propagation.     

Mechanical behavior and fracture toughness of epoxy composites reinforced with combination of fibrous and spherical nanofillers

Epoxy nanocomposites modified with multiwalled carbon nanotubes (MWNTs), rubber nanoparticles (RNPs), and the combinations of MWNTs and RNPs were prepared. The effects of multiphase reinforcements on mechanical and fracture properties of epoxy resin were investigated. With combined use of RNPs and MWNTs, the ternary nanocomposites exhibit simultaneous enhancement in stiffness, strength and fracture toughness. Maximum increase of 101% in K_IC and 294% in G_IC of the ternary composites were achieved in this study. A modified model was developed to predict the modulus of the ternary composites based on the Halpin‐Tsai equation, which was proved to match the experimental results exactly. DSC, TEM, SEM, and AFM studies were carried out to evaluate the composition and microstructure of the binary and ternary composites. POLYM. COMPOS., 36:2147–2156, 2015. © 2014 Society of Plastics Engineers     

Thermotropic liquid crystal polymer fabric reinforced polyimide composite materials

An aromatic copolyeste thermotropic liquid crystal polymer (LCP) fabric was used to reinforce a polyimide (PI) matrix to produce composites. The LCP/PI composite was made to eliminate directional difference in the mechanical properties of LCP by controlling the individual reinforcement fabric alignment in different directions without losing any mechanical properties. As a result, a transversely isotropic LCP composite material could be obtained from the highly anisotropic LCP fiber. Interfacial adhesion between the LCP and polyimide was greatly improved by a NH₃/H₂ plasma treatment on the LCP fabric, thereby the significantly improving mechanical properties of the composite. Moreover, inter‐laminar shear strength of the LCP/PI composite was further increased after heat treatment at 220°C for 1 hour. The LCP/polyimide composite retains stable mechanical properties up to 250°C.     

Role of fillers on three‐body abrasive wear behavior of glass fabric reinforced epoxy composites

The article summarizes an experimental study on the abrasive wear behavior of particulate filled glass‐epoxy (G‐E) composites. The two fillers investigated were graphite and alumina. The wear behavior was assessed by rubber wheel abrasion tests. The tests were carried out for 270, 540, 810, and 1080 m abrading distances at 22 and 32 N loads. The worn surfaces were examined using scanning electron microscopy (SEM). The results showed varied responses under different abrading distance because of the addition of fillers in G‐E composites. Graphite filler, however, performed poorly resulting in significant deterioration in wear performance while the alumina filled G‐E composite showed improved abrasion resistance. Selected mechanical properties such as hardness, tensile strength, and elongation at fracture were analyzed for investigating wear property correlations. The SEM studies indicate the reasons for failure of composites and influencing parameters. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

电纺纳米纤维增强聚合物复合材料的研究进展

与作为填料的普通纤维相比,通过静电纺丝所得纳米纤维(简称电纺纳米纤维)的长径比及比表面积较大,相对于基体材料具有较大的模量和韧性,对聚合物基体有较好的力学增强效果;电纺纳米纤维在复合材料中应力集中程度低、与聚合物基体间界面结合较好。加入电纺纳米纤维可以提高复合材料的性能,如拉伸及弯曲强度、模量,抗冲击性能等都有较大提高。电纺纳米纤维在聚合物基体中的分散及其与基体间的界面黏结等问题有待进一步研究和改善。     

Investigation on mechanical and tribological behavior of naturally woven coconut sheath‐reinforced polymer composites

The article presents the results of experimental investigation on mechanical and dry sliding wear behavior of unsaturated polyester resin (USP), reinforced with naturally woven coconut sheath and glass fibers. The mechanical properties of coconut sheath (N) and glass fiber (G) reinforced polyester composites were studied, and the tribological behaviors were tested on pin‐on‐disc sliding wear tester. Mass loss was determined as a function of sliding distance for a sliding velocity of 3.5 m/s and an applied normal load of 40 N. The experimental result revealed that the mechanical properties and wear resistance of the composites depend on the wt% reinforcement of coconut sheath/glass fiber and sliding distance. The hybrid reinforcement (GGN) greatly increased the mechanical properties of USP. At lower sliding distance, the N‐reinforced USP had lower wear loss, whereas at higher sliding distance, the hybrid fiber‐reinforced (GGN) USP composite had lower wear loss. Furthermore, the work showed that the higher sliding distance bring about changes in the worn surface features such as interface separation, inclined fracture of fibers, loss of matrix, and the appearance of debris with the two different fibers. The worn surfaces were also examined by scanning electron microscopy. The study showed differing trends with load for the two types of reinforcements. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Research progress of basalt fiber reinforced polymer composites

玄武岩纤维的综合性能优异,是聚合物复合材料的理想增强体,在高强度、耐高温、耐酸碱腐蚀、耐烧蚀和耐摩擦等特殊领域展示了良好的应用前景。本文对玄武岩纤维聚合物基复合材料研究中的纤维与基体的界面改性、不同聚合物基体的复合材料以及玄武岩纤维与其它纤维的混杂三个方面进行了综述。目前对于玄武岩纤维界面性质的基础研究深度不足,有些复合材料的研究和制备方法还没有应用于玄武岩纤维上,使得玄武岩纤维复合材料的优势还没有得到充分的发挥。因此,应结合玄武岩纤维及其复合材料的特性,开发适用性强的和性价比好的产品,扩大应用范围。     

有机涂层在纤维增强聚合物基复合材料中的应用

介绍了不同涂层在纤维增强聚合物基复合材料中的应用和新近研究成果,其中包括偶联剂类(硅烷偶联剂、金属偶联剂)涂层和聚合物涂层(环氧树脂类和非环氧聚合物类),并综述了各种涂层方法(溶液浸渍法、界面原位聚合法、等离子体聚合法和电聚合法)的特点和应用研究进展。