航空用复合材料纤维织物标准研究

复合材料在航空领域的广泛应用,使得标准体系的研究也不断深入.以直升机为例,介绍我国直升机复合材料用纤维织物标准,通过对国内外复合材料用织物标准现状的分析研究,确定我国直升机所用织物标准的主要技术要素及试验方法.最后对我国直升机用复合材料标准体系的建立提出了合理化建议.     

缝编织物复合材料在船舶工业中的应用

本文介绍了一种新型船用织物及其复合材料的特性。由于该织物具有纤维无卷曲、多层、多轴向、平行铺放等特性。提高了复合材料的增强率、可设计性和可混编性，从而提出新的设计理念。文中所举实例表明，按照新的设计理念，在船舶制造中合理地使用该材料，减轻了船体重量，降低了制造成本。     

Physical and mechanical characterization of jute fabric composites

As‐received and washed jute fabrics were used as reinforcement for a thermoset resin. The mild treatments performed on the jute fabrics did not significantly affect their physical and thermal behaviors. The washed fibers absorbed less water than the unmodified (as received) ones, indicating that the coating used to form the fabrics was hygroscopic. Measurements of the fiber mechanical properties showed a high dispersion due to fiber irregularities, although the values obtained were in agreement with data reported in the literature. These results were also analyzed with the Weibull method. To investigate the effect of the jute treatments on the interface properties, impact, compression, and tensile tests were carried out. The composites made from as‐received jute had the highest impact energy, which was probably associated with weak interfacial adhesion. Composite samples behaved more ductilely in compression than in tensile situations due to the brittle characteristics of the resin used as matrix. The effect of the orientation of the fibers with respect to the direction of the applied force in the different mechanical tests was also studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 639–650, 2005     

Durability of non-crimp fabric composites in aqueous environments

Abstract

Glass fibre composites subjected to hot water exhibit a reduction in stiffness and strength owing to a combination of matrix plasticisation and fibre/matrix interfacial degradation. If the composite system is subjected to some form of mechanical damage such as cracking from an external impact, the net consequence of water exposure is more difficult to predict.

This paper reports on the effects of water exposure at two temperatures (65 and 93°C) on non-crimp, quadriaxial, glass fabric systems with a polyester matrix. The residual properties are measured using the compression after impact test. It is shown that the residual properties of laminates tend to reach a minimum plateau after extended exposure to water, the value of which is dependent on the temperature of the water. It is also seen that the effects of impact damage vary depending on whether or not the impact is experienced before or after the water exposure. Impacting after conditioning produces a greater density of through thickness damage, which results in a lower compression after impact strength than impacting before conditioning.     

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.     

Tribological behavior of Kevlar fabric composites filled with nanoparticles

The friction and wear characteristics of ZnO‐ or montmorillonite‐nanoparticle‐filled Kevlar fabric composites with different filler proportions when sliding against stainless steel pins under dry friction conditions were studied, with unfilled Kevlar fabric composites used as references. The worn surface and transfer film of Kevlar fabric composites were then examined with a scanning electron microscope. It was found that ZnO and montmorillonite as fillers could improve the tribological behavior of the Kevlar fabric composites with various applied loads, and the best antiwear property was obtained with the composites containing 5 wt % ZnO or montmorillonite. This indicated that these nanoparticles could prevent the destruction of Kevlar fabric composites during the friction process. The transfer film established by these nanoparticles during the sliding wear of the composites against their metallic counterpart made contributions to reducing the friction coefficient and wear rate of the Kevlar fabric composites measured in the test. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Structure–tensile property relationship of knitted fabric composites

This paper reports some further studies on the tensile properties of plain weft knitted DuPont Kevlar fiber fabric reinforced epoxy matrix composites. One aim of this work is to investigate systematically the anisotropy of knitted fabric composites. Tensile tests were conducted at different off‐axial angles (0°, 30°, 45°, 60° and 90°) with respect to the wale direction. Fracture modes corresponding to this off‐axial variation were clearly identified. The elastic modulus and tensile strength were found to be the highest in the wale direction (0°), but decreased gradually towards the course direction (90°). This anisotropic study was carried out on both single layered and multilayered (four layered) knitted fabric composites. Another aim is to study the effect of specimen width (or number of loops per specimen width) on the tensile properties. This study indicated an optimum number of loops per sample width required to obtain meaningful tensile test results. Further, edge effect on the tensile properties of the knitted fabric composites was also investigated in the paper. This was achieved through comparative studies on cut and uncut four layered specimens. In the cut specimens the continuity of the yarns is lost at the cut edges, which show a marginal variation in the properties compared with the uncut specimens where the yarns are continuous throughout the specimen. Finally, a study was also carried out to investigate the effect of loop size (or stitch density) on the tensile strength and stiffness of the single layered composites.     

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     

Model for thermal conductivities in spun yarn carbon fabric composites

A study on the thermal conductivities of spun yarn‐type carbon/phenolic (spun C/P) composites using a thermal‐electrical analogy method is presented. This method is based on the similarity between the partial differential equation that governs the thermal potential and electrical potential distribution. The unit cell of a laminate composite is divided into several conduction elements. By constructing an equivalent thermal resistance network in series, and in parallel based on analogy, we were able to predict the thermal conductivity of the composite. The prediction values obtained from the model are compared with known thermal conductivities on a carbon/epoxy composite with an eight‐harness satin (8HS) texture. It is shown that the model provides a good estimate of the thermal conductivity of the spun yarn fabric‐reinforced composite. With the use of this model, the thermal conductivity of the spun C/P composites with 8HS was validated experimentally. Good agreement was found between the present approach and the experimental results. POLYM. COMPOS., 26:791–798, 2005. © 2005 Society of Plastics Engineers     

Crack growth and fracture behavior of fabric reinforced polymer composites

The objective of this study is to understand and characterize crack deflection and sub-crack growth in fabric laminate composites. The theory of crack digression based on the Cook-Gordon mechanism of crack blunting and the criterion developed by Kendall were used to study the crack propagation phenomenon. A simple approach has been developed to evaluate the cohesive and adhesive fracture energies, which play a vital role in the study of strength and toughness of the fabric laminate composites. The effects of strain rate and quasi-static crack velocity on these energy values were identified. This study explored the possibility of selftoughening in an otherwise brittle composite system. Two competing mechanisms have been identified that control crack propagation in fabric laminate composites.     

Mapping of stress distribution in woven‐fabric composites

Mapping of the stress distribution in composite materials, both at the fiber/matrix interface and in the composite constituents, is important to understand the material mechanical response. Stress mapping can help predict composite behavior under certain stresses especially failure or delamination. In this work, two analytical models were proposed to map the stress distribution at fiber, matrix and fiber/matrix interface utilizing the concept of stress superposition. The first model dealt with the fiber in the longitudinal direction considering axisymmetric conditions. The second model addressed the fiber stress distribution in the transverse direction. Experimental data from four‐point flexural tests of woven fabric composites was processed using the Graphical Integrated Numerical Analysis (pcGINA) to obtain the maximum stress in the target laminate and this value was used as the input for the two analytical models. The value for the maximum interfacial shear stress was calculated using the models and results were compared to pull‐out fiber test values obtained from literature. Good agreement was observed between the model calculations and the literature data. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Erosive wear of carbon fabric reinforced polyetherimide composites: Role of amount of fabric and processing technique

Plain weave carbon fabric (CF) reinforced Polyetherimide (PEI) composites, hereafter referred to as CF‐PEI composites, containing 40, 55, 65, 75, and 85 vol% of CF were developed using impregnation technique and compression moulding. An additional CF‐PEI composite containing 52 vol% of CF was also fabricated using film technique and compression moulding. These composites were developed in order to explore the effect of fabric content and processing technique on strength properties and erosive wear performance of PEI. These six composites along with unfilled PEI were evaluated for their physical and mechanical properties. The erosive wear performance of these materials was evaluated using angular silica particles as erodent at an impingement angle of 30°. It was observed that fabric content strongly influenced the strength properties as well as erosion resistance. Strength performance, however, did not linearly increase with increase in fabric content. Lowest (40%) and highest (85%) amount of fabric proved least effective in this regard. Similar observations were observed in the case of wear resistance (W_R). CF in the range of 55–75 vol% proved optimum for strength properties and wear performance barring PEI, which showed highest W_R. Between the two processing techniques, impregnation technique (I) proved far superior to the film technique (F) in both strength and wear performance. A fairly good correlation was observed between erosion resistance and a product of interlaminar shear strength, resilience, and elongation. SEM studies on worn surfaces supported the wear behavior. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Mechanical and thermal properties of polypropylene/modified basalt fabric composites

Basalt fabric (BF) was first treated with silane coupling agent KH550, modified basalt fabric (MBF) was obtained. Then MBF were molded with polypropylene (PP) matrix, and polypropylene/modified basalt fabrics (PP/MBF) composites were obtained. The influence of concentration and treating time of KH550 on MBF were characterized by hydrophilicity and lipophilicity. The tensile strength and morphology of basalt fabric were tested by single filament strength tester and scanning electron microscopy. The mechanical properties of composites were measured with electronic universal testing machine and impact testing machine, and the thermal properties were tested by thermogravimetric analysis and dynamic mechanical analysis. The results showed that the lipophilicity of MBF is improved significantly by KH550 while the tensile is nearly damaged. The mechanical properties of composites are larger than that of pure PP, among which the impact property was improved the most, showing 194.12% enhancement. The thermal stability and dynamic viscoelasticity were better than pure PP; furthermore, the concentration of KH550 virtually had no effect on the thermal stability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42504.     

Improving the bonding strength of laminated composites by optimizing fabric composition

Delamination is the most common failure mode in laminated composites due to the weaker strength in the through‐the‐thickness direction. Air‐jet texturing is used to produce bulk and loops in the yarn which provides more contact surface between fibers and resin. The development and characterization of core‐and‐effect textured glass yarns and the effect of texturing on the mechanical properties of laminated composites were presented in previous papers. This article describes the optimization of textured composites by varying the type and combination of constituent yarns for improving the mechanical properties. Composites with combinations of various textured yarns and non‐textured yarns were made. It was observed that the composites made from fabrics having non‐textured yarn in the warp and core‐and‐effect textured yarn in the weft had the best combination of mechanical properties. They maintained the tensile and flexure properties of composites with non‐textured yarns but had significantly higher interlaminar shear strength. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Friction and wear behavior of glass fabric/phenolic resin composites with surface‐modified glass fabric

Untreated, air‐plasma‐bombarded, and β‐aminoethyltrimethoxylsilane‐silanized glass fabric (GF) was used to prepare GF/phenolic composites by dip coating in a phenolic adhesive resin and successive curing. The tribo‐performances of these GF/phenolic composites sliding against AISI‐1045 steel were evaluated with a pin‐on‐disc wear tester. The chemical composition of the untreated and surface‐treated GF was analyzed with Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. The interfacial regions between the phenolic resin and GF and the worn surfaces of the composites were analyzed with scanning electron microscopy. The results show that the GF/phenolic composite with β‐aminoethyltrimethoxylsilane‐silanized GF had the highest load‐carrying capacity and best tribo‐performance, and it was followed by the composite with plasma‐treated GF. The improved tribo‐performance of the GF/phenolic composite made of surface‐treated GF was attributed to the strengthened interfacial bonding between the treated GF and the phenolic adhesive resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Green composites from wheat protein isolate and Hildegardia Populifolia natural fabric

Completely biodegradable composites were prepared using modified wheat protein isolate (WPI) as matrix and the uniaxial natural fabric Hildegardia Populifolia as reinforcement. The WPI was cross‐linked with glutaraldehyde in the presence of glycerol plasticizer. These polymer composites were subsequently subjected to evaluation for their mechanical, morphological (SEM), thermal (TGA/DMA) properties, and biodegradation behavior. The mechanical properties such as tensile strength and flexural strength of the composite increased with increase in fabric loading up to 10% and decreased therefore. Further, the alkali treatment of the fabric and use of a coupling agent enhanced the mechanical properties. The scanning electron micrographs of the fractured surface of the composites indicated facilitation of better bonding between the matrix and reinforcement by the coupling agent. In case of thermal behavior, results indicated that the presence of fabric affected the thermal stability of polymer matrix. Biodegradability of the composites was also been studied by soil burial method, and the composites were found to degrade up to 95% in 35 days. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Mechanical performance of woven carbon fabric reinforced pCBT composites with nanosilica particles

The effect of nanosilica content (0, 0.5, and 2 wt%) on mechanical performance of carbon fabric woven cloth reinforced polymerized poly(butylene terephthalate) resin composites (CF/pCBT) is investigated. The catalyst and nanosilica particles are added on the prepreg surface, and hot‐press processing is adopted in order to manufacture CF/pCBT composites. The experimental results reveal that nanosilica could enhance the mechanical performance of CF/pCBT composites. After adding nanosilica in the composites, elastic modulus enhances 23.96%, and Mode‐II fracture toughness increases 380.43%. Scanning electron microscope observation shows that dispersity of nanoparticles in composites plays an important role on the overall mechanical performance of the obtained composites. Furthermore, failure mechanism has been analyzed according to the damage morphology. POLYM. COMPOS., 38:2528–2535, 2017. © 2015 Society of Plastics Engineers     

Influence of solid lubricant reinforcement on wear behavior of Kevlar fabric composites

The friction and wear behavior of Kevlar fabric composites reinforced by PTFE or graphite powders was investigated using a Xuanwu‐III friction and wear tester at dry sliding condition, with the unfilled Kevlar fabric composite as a reference. The worn surfaces were analyzed by means of scanning electron microscope, and X‐ray photoelectron spectroscopy. It was found that PTFE or graphite as fillers could significantly improve the tribological behavior of the Kevlar fabric composites, and the Kevlar fabric composites filled with 20% PTFE exhibited the best antiwear and antifriction ability among all evaluated cases. The transfer films established with two lubricants in sliding wear of composites against metallic counterparts made contributions to reducing friction coefficient and wear rate of Kevlar fabric composites. In particular, FeF₂ generated in the sliding of Kevlar fabric composites filled with PTFE against counterpart pin improved the bonding strength between the transfer film and counterpart surface, which accounted for the lowest friction coefficient and wear rate of the Kevlar fabric composites filled with PTFE measured in the testing. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Tensile properties of natural fabric Hildegardia populifolia/polycarbonate toughened epoxy composites

The environmentally friendly composites of natural fabric Hildegardia populifolia/polycarbonate toughened epoxy were prepared. The effect of fabric content and the orientation of the fibers in the fabric on the tensile properties of the composites was studied. The effect of alkali treatment of the fabric and a silane coupling agent on the tensile properties was also studied. The tensile properties improved with alkali treated fabric content when a coupling agent was used. Polym. Compos. 25:563–568, 2004. © 2004 Society of Plastics Engineers.     

The contribution of thermal stresses to the failure of Kevlar fabric composites

The mismatch in thermoelastic properties between fiber and matrix in Kevlar 49 fabric-epoxy composites is shown to result in significant thermal stresses with cool down from processing temperatures. Cooling generates local transverse tensile stresses that can potentially initiate microcracking at ambient conditions. A temperature reduction also places the curved fiber in the fabric composite in axial compression. This compression adds to the bending strain in the fiber, resulting in significant local reduction of its inherently low compressive load-bearing capability. The combination of thermal stresses and external compressive loads that are below ultimate values can cause local compressive failure of the fiber. The kink bands formed as a result of compressive failure of Kevlar fiber are expected to cause debonding between fiber and matrix and, therefore, are also potential sites for crack initiation. Thus, thermal stresses can contribute to the initiation of at least two damage mechanisms that may severely limit the compressive and flexural fatigue strength of Kevlar fabric composites at and below ambient temperature.