Showing papers in "Journal of Composite Materials in 2012"
TL;DR: The use of hemp fibers as reinforcement in composite materials has increased in recent years as a response to the increasing demand for developing biodegradable, sustainable, and recyclable materia as mentioned in this paper.
Abstract: The use of hemp fibers as reinforcement in composite materials has increased in recent years as a response to the increasing demand for developing biodegradable, sustainable, and recyclable materia...
422 citations
TL;DR: In this paper, the authors describe the input data provided for use in the Second World Wide Failure Exercise (WWFE-II) for benchmarking triaxial failure criteria, including three-dimensional elastes.
Abstract: This article gives details of the input data provided for use in the Second World-Wide Failure Exercise (WWFE-II) for benchmarking triaxial failure criteria. It includes (a) three-dimensional elast...
162 citations
TL;DR: In this article, a pressure-dependent three-dimensional constitutive law is proposed to predict failure for laminated composites, where the nonlinear constitutive response in shear and in the transverse and through-the-thickness directions, which is measured experimentally, is incorporated directly into the model.
Abstract: This paper presents a pressure-dependent three-dimensional constitutive law to predict failure for laminated composites. The nonlinear constitutive response in shear and in the transverse and through-the-thickness directions, which is measured experimentally, is incorporated directly into the model. In addition, secant stiffnesses are dependent on the state of hydrostatic pressure and on the general state of strain. The failure criteria distinguish between matrix failure, fibre kinking and fibre tensile failure. In-situ strengths are used for matrix failure. Propagation of failure takes into consideration the fracture energy associated with each failure mode and, for matrix failure, the accumulation of cracks in the plies. A detailed discussion is undertaken of the mismatch between the available experimental data and the physical properties required to characterise the constitutive response up to final failure. The model is employed to make blind predictions of the triaxial failure envelopes and stress–st...
143 citations
TL;DR: In this article, a durability study of glass fiber reinforced polymer (GFRP) bars within concrete environment and recommendations for effective accelerated ageing methods, data reduction and validation, and formulation of master curves for long-term predictions.
Abstract: This article presents a durability study of glass fiber reinforced polymer (GFRP) bars within concrete environment and provides recommendations for effective accelerated ageing methods, data reduction and validation, and formulation of master curves for long-term predictions. Concrete beams reinforced with GFRP bars were immersed in tap water inside temperature-controlled tanks. Sustained load was applied to beam samples, and elevated temperatures were used to accelerate the ageing of GFRP bars. After exposure, GFRP bars were tested for residual tensile strength, which was considered as a measure of the durability performance of the specimens. Scanning electron microscopy (SEM) images were used to evaluate the microstructural changes of conditioned specimens. Short-term (up to 270 days) results showed that compared to alkalinity and low sustained load, moisture and elevated temperature played much more important roles in accelerating environmental attack to GFRP bars. Based on the short-term test results,...
137 citations
TL;DR: In this article, a computational framework for the simulation of progressive failure in composite laminates is presented, using the phantom-node method (a variation to the XFEM) for a mesh independent representat...
Abstract: A computational framework for the simulation of progressive failure in composite laminates is presented. The phantom-node method (a variation to the XFEM) is used for a mesh-independent representat...
129 citations
TL;DR: In 2004, the First World Wide Failure Exercise dealing with benchmarking recognized failure criteria under two-dimensional, in-plane loadings was completed as mentioned in this paper, which was based on the success and the les...
Abstract: In 2004, the authors completed the First World-Wide Failure Exercise dealing with benchmarking recognised failure criteria under two-dimensional, in-plane loadings. Based on the success and the les...
125 citations
TL;DR: In this article, carbon nanotube (CNT)/cement composites with different concentration levels of multi-walled CNT and water/cement ratios are fabricated by comparing the responses of electrical resistance of the composite.
Abstract: Carbon nanotube (CNT)/cement composites with different concentration levels of multi-walled CNT (MWNT) and water/cement ratios are fabricated. By comparing the responses of electrical resistance of...
121 citations
TL;DR: In this paper, the inter-ply characteristics of polymeric prepreg composites influence their interlaminar fracture toughness and the overall performance, and the interply characteristics are investigated.
Abstract: The inter-ply characteristics of polymeric prepreg composites influence their interlaminar fracture toughness and the overall performance. This article embarks on engineering the inter-ply interfac...
118 citations
TL;DR: In this paper, the water absorption behavior of a glass/jute fiber-reinforced unsaturated polyester hybrid composite was found to follow a non-Fickian behavior.
Abstract: The use of natural fibers in polymer composites has given renewed interest to the development of green composites today. However, the moisture absorption of natural fibers gives serious concern, especially for their potential outdoor applications. This article reports the study results on the water absorption of pultruded jute/glass fiber-reinforced unsaturated polyester hybrid composites, which was subjected to various water conditions and their effects on its mechanical properties. Water absorption tests were performed by immersing composite specimens into three different water conditions, namely: distilled water, sea water, and acidic water, which were at room temperature, for a period of 3 weeks. The characteristic parameter of diffusion coefficient (D) and maximum moisture content (Mm) were determined from the obtained water absorption curves. The water absorption behavior of the glass/jute fiber-reinforced unsaturated polyester hybrid composite was found to follow a non-Fickian behavior. The effects...
116 citations
TL;DR: In this article, epoxy-based laminates of basalt (BFs), E-glass (GFs), and carbon (CFs) fibers with the same areal density were used to produce elastic moduli and strength values.
Abstract: Fabrics of basalt (BFs), E-glass (GFs), and carbon (CFs) fibers with the same areal density were used to prepare epoxy-based laminates. The BF laminates presented elastic moduli and strength values...
103 citations
TL;DR: In this article, the experimental results of the mechanical and tribological properties of Al7075-SiC composites are presented, and it is shown that the density of the composites increase with increased SiC contents and are in line with the values obtained by the rule of mixtures.
Abstract: In this article, the experimental results of the mechanical and tribological properties of Al7075–SiC composites are presented. The composites of Al7075 containing 2–6 wt% SiC were fabricated by liquid metallurgy route. The experimental results showed that the density of the composites increase with increased SiC contents and are in line with the values obtained by the rule of mixtures. The hardness and tensile strength of the Al7075–SiC composites are found to be increased by increased volume percentage of ceramic phase at the cost of reduced ductility. The wear properties of the composites containing SiC exhibited the superior wear-resistance properties.
TL;DR: In this paper, the effects of variation in autoclave pressure, temperature, and vacuum-application time on porosity, hot/wet (H/W) and room temperature/dry (RT/D) were investigated.
Abstract: This article presents results from investigation of the effects of variation in autoclave pressure, temperature, and vacuum-application time on porosity, hot/wet (H/W) and room temperature/dry (RT/...
TL;DR: In this article, the influence of an unidirectional carbon fabric layer on the mechanical performances of bidirectional flax fabric/epoxy composites used for structural applications was studied.
Abstract: In this work, the influence of an unidirectional carbon fabric layer on the mechanical performances of bidirectional flax fabric/epoxy composites used for structural applications was studied. Two d...
TL;DR: In this paper, the pultruded composite rods made from hemp and wool fiber reinforcements were analyzed and the results showed that the composite using polyurethane resin system has higher specific tensile and compressive strength compared with the polyester and vinyl ester composites.
Abstract: Great efforts are being made at Brunel University, UK in attempt to develop natural fiber composites with desired structure and good overall properties for construction. This work focuses on the mechanical and morphological characterization of the pultruded composite rods made from hemp and wool fiber reinforcements. The results showed that the composite using polyurethane resin system has higher specific tensile and compressive strength as well as the Young's and compressive moduli compared with the polyester and vinyl ester composites, while the polyester composite exhibits better flexural strength. The SEM observation of the cross section and layered polyester and polyurethane composites has found defects on the interface of fibers and resin matrix. It is also revealed that fibers are not evenly distributed in the composites and more resin aggregates in areas close to rod surface. Meanwhile, voids have been noticed existing in both composites, but more of them are found in the polyurethane-matrix rod, ...
TL;DR: In this paper, various kinds of organo-modified clays were dispersed at different amounts in an epoxy matrix, and the viscosity of the epoxy resin resulted still acceptable for a possible usage a...
Abstract: Various kinds of organo-modified clays were dispersed at different amounts in an epoxy matrix. After clay addition, the viscosity of the epoxy resin resulted still acceptable for a possible usage a...
TL;DR: In this article, fiber composites with recycled high-density polyethylene matrix were prepared in various compositions ranging from 20 to 40% of fiber volume fraction, and the fiber-matrix interface was improved.
Abstract: Hemp fiber composites with recycled high-density polyethylene matrix were prepared in various compositions ranging from 20 to 40% of fiber volume fraction. The fiber–matrix interface was improved u...
TL;DR: Water absorption behavior and mechanical properties of specimens of an epoxy resin casting and the glass fiber reinforced epoxy matrix composites (GFRP) with two fiber volume fractions (Vf) immerse...
Abstract: Water absorption behavior and mechanical properties of specimens of an epoxy resin casting and the glass fiber reinforced epoxy matrix composites (GFRP) with two fiber volume fractions (Vf) immerse...
TL;DR: In this paper, the physical properties of the recycled laminates are evaluated by means of pulse-echo ultrasound, visual microscopy, and fiber volume content, and the results show that the recycled material offers prom...
Abstract: Solid carbon fiber/epoxy laminates manufactured by liquid resin infusion of twill fabric reinforcement are recycled in a bath of boiling sulfuric acid to separate the fibers from the matrix. The recycled reinforcement consists of long fibers arranged in a random, entangled mat. Using the same epoxy matrix and infusion materials and process, the recycled fibers are reutilized to manufacture solid laminates. The physical properties of the recycled laminates are evaluated by means of pulse-echo ultrasound, visual microscopy, and fiber volume content. The average fiber volume content of the recycled laminates is 33%, compared to the 62% of the twill laminates. The mechanical properties of the recycled composite include tension modulus and strength, compression modulus and strength, three-point bend flexure strength, and short beam shear strength. The properties are compared against the values of the twill reinforcement with quasi-isotropic stacking sequence. Results show that the recycled material offers prom...
TL;DR: In this paper, the development of fabrication techniques and experimental measurements of out-of-plane fiber waviness in a continuous fiber-reinforced polymer composite were presented, along with a detailed characterization of the fabrication process.
Abstract: This study presents the development of fabrication techniques and experimental measurements of out-of-plane fiber waviness in a continuous fiber-reinforced polymer composite. Literature on characte...
TL;DR: A new method for the development (design, fabrication, and characterization) of asbestos-free rubbers for use as rocket motor insulators is presented in this article, which is based on chopped carbon fibbers.
Abstract: A new method for the development (design, fabrication, and characterization) of asbestos-free rubbers for use as rocket motor insulators is presented. Such insulation is based on chopped carbon fib...
TL;DR: In this article, the characterization and modeling of thermoplastic and thermosetting matrix composites under load in fire was discussed and small-scale tests were found to provide a cost-effective means of characterizing loadbearing behavior of composites in fire and a useful framework for materials development.
Abstract: This paper discusses the characterization and modeling of thermoplastic and thermosetting matrix composites under load in fire. Small-scale tests were found to provide a cost-effective means of characterizing load-bearing behavior of composites in fire and a useful framework for materials development. This paper demonstrates the modeling of thermal and decomposition behavior during the test and the extension of this modeling to include mechanical response and failure behavior. The work necessitated measurement of strength and stiffness over a wide temperature range, with interesting results up to the point of resin decomposition. The approach was applied to three 12 mm thick glass reinforced systems: vinyl ester, polyester, and polypropylene. The laminates were subjected to a one-sided 50 kW·m−2 heat flux, using a propane burner. Thermal behavior was modeled using a simplified version of the Henderson equation to predict the evolution of temperature and residual resin content through the thickness. These ...
TL;DR: In this article, different types of surface treatment were used to reinforce concrete in an attempt to overcome the corrosion issue encountered with ordinary steel, using glass fiber-reinforced polymer bars.
Abstract: Glass fiber-reinforced polymer bars are currently used to reinforce concrete in an attempt to overcome the corrosion issue encountered with ordinary steel. Different types of surface treatment were...
TL;DR: In this article, graphite nanoplatelets (GNP) were added to polycarbonate (PC) and polyethylene (PE) to produce electrically conductive composites.
Abstract: Exfoliated graphite nanoplatelets (GNP) can be added polymers to produce electrically conductive composites. In this study, varying amounts (2–15 wt%) GNP were added to polycarbonate (PC) and the r...
TL;DR: In this article, the performance of polydimethylsiloxane (PDMS) nanocomposites with carbon black (CB) and multi-walled carbon nanotube (MWCNT) fillers was studied.
Abstract: In this work, the performance of polydimethylsiloxane (PDMS) nanocomposites with carbon black (CB) and multi-walled carbon nanotube (MWCNT) fillers was studied. The carbon nanofillers were first in...
TL;DR: Rotary ultrasonic machining (RUM) has been successfully employed to drill holes in carbon fiber-reinforced plastic (CFRP) composites as discussed by the authors, which is involved in many applications of CFRP composites.
Abstract: Drilling is involved in many applications of carbon fiber-reinforced plastic (CFRP) composites. Rotary ultrasonic machining (RUM) has been successfully employed to drill holes in CFRP using either ...
TL;DR: In this article, the role of multi-walled carbon nanotubes (MWCNTs) on the tension and in-plane shear behaviors of carbon fiber reinforced polymer composites was examined.
Abstract: This investigation experimentally examines the role of multi-walled carbon nanotubes (MWCNTs) on the tension (on-axis tension test) and in-plane shear (off-axis tension test) behaviors of carbon fiber reinforced polymer composites. Both pristine and chemically functionalized MWCNTs were utilized with four different loadings: 0.1, 0.5, 1.0, and 1.5 wt% of epoxy. Our investigation showed that with 1.5 wt% functionalized MWCNTs, failure strain, ultimate strength, and toughness of the off-axis tension test are improved by 39%, 51%, and 121%, respectively. On the contrary, limited improvements were observed for the on-axis tested samples with functionalized or pristine MWCNTs.
TL;DR: In this article, a hydrothermal method was used to convert graphene oxide to graphene in water and polyvinylpyrrolidone was added to improve dispersion of graphene and form a stable graphene solution with a high concentration.
Abstract: Hydrothermal method was used to convert graphene oxide to graphene in water. Polyvinylpyrrolidone was added to improve dispersion of graphene and form a stable graphene solution with a high concentration. This stable graphene solution was used to mix with waterborne polyurethane (WPU) to prepare WPU/graphene composites. The electrical conductivity of WPU was greatly improved with incorporation of graphene, and when the filling amount of graphene is 4.0 wt%, the conductivity of the composite reaches 8.30 × 10−4 S cm−1, which is a little higher than that of the composite prepared by in situ method.
TL;DR: In this article, a micromechanical approach is adopted to calculate material properties of the tows, which are critical compositions of braided composites, by applying periodical boundary conditions (PBC) in correspondence to the four types of braids.
Abstract: Biaxial and triaxial braided composites are modeled using finite element methods to predict effective material properties: for biaxial braids, diamond pattern (1/1), regular pattern (2/2), and Hercules pattern (3/3) are modeled, while for triaxial braids, a regular pattern (2/2) is modeled. A micromechanical approach is adopted to calculate material properties of the tows, which are critical compositions of braided composites. By applying periodical boundary conditions (PBC), four representative unit cells (RUC) in correspondence to the four types of braids are analyzed and compared. Subsequently, effective material properties are obtained with the braiding angle varying from 15° to 75° with an increment of 5°, from which the variation of the engineering constants with the braiding angle is studied. The prediction results are compared with the experimental values for two material systems, and good agreement is achieved.
TL;DR: In this article, the originators of three-dimensional failure theories applied their methods to 12 carefully selected challenging problems in the Second World Wide Failure Exercise (WWEFLE) in the early 1990s.
Abstract: As a part of the Second World-Wide Failure Exercise, the originators (or their collaborators) of three-dimensional failure theories applied their methods to 12 carefully selected challenging proble...
TL;DR: A biodegradable polymer composite containing lignin from sugarcane bagasse and poly(3-hydroxybutyrate-co-3hydroxyvalerate) (PHBV) was produced and characterized in terms of its thermal, morphological and structural properties as mentioned in this paper.
Abstract: A biodegradable polymer composite containing lignin from sugarcane bagasse and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was produced and characterized in terms of its thermal, morphologi...