Carbon Fiber Reinforced Resin Composites Research Articles

An ultrasound-assisted resin transfer molding to improve the impregnation and dual-scale flow for carbon fiber reinforced resin composites

The imbalance of the dual-scale flow, i.e., microscopic intra-bundles and macroscopic inter-bundles flow, always generates voids in resin transfer molding (RTM) of composites, substantially weakening the mechanical performance. An ultrasound-assisted strategy to improve the impregnation and to balance dual-scale flow is promising to suppress the voids, while, it has still not been explored. Here, an ultrasound-assisted RTM for carbon fiber reinforced resin composites, realized by a self-developed device, is originally proposed. The influences of ultrasound vibration on the carbon fibers, resins, wettability, and impregnation process are systematically explored. Furthermore, the dual-scale flow, affected by the ultrasound vibration, is optimized. It is identified that the ultrasound vibration effectively reduces the viscosity of the resin and increases the roughness and surface activity of the fibers, hence significantly weakening the delayed impregnation in the intra-bundles, and speeding up the impregnation velocity in the inter-bundles. The reduction of the viscosity and the contact angle synergistically lowers the modified capillary number Ca*, hence balancing the dual-scale flow, while the excessively high impregnation velocity in the inter-bundles detrimentally enlarges Ca*, leading to the imbalance of the dual-scale flow. Accordingly, a critical ultrasound energy input (4 min of ultrasound vibration at the power range of 400–600 W) is figured out to achieve an optimal Ca*, providing a promising approach to suppress the flow-induced voids in composites manufacturing by RTM.

The distinctions of the interfacial nanostructures and properties between carbon fiber reinforced fast and conventional curing epoxy composites subjected to hydrothermal treatments

The vital role of the interphase in loading transfer in carbon fiber reinforced resin composites has received considerable critical attention. In this study, to quantitatively distinguish between the effects of hydrothermal aging on the interfacial nanostructures and properties of carbon fiber reinforced fast and conventional curing epoxy composites, peak force quantitative nano-mechanics (PF-QNM) technique by atomic force microscopy (AFM) was utilized to determine the interfacial modulus, adhesion and thickness. In addition, the shear behavior was studied by short-beam strength test, and the water uptake was investigated by water adsorption test. Based on the modulus contrast of the interphase in PF-QNM modulus image, the average interfacial thickness of the fast curing epoxy composites after 18 h of hydrothermal aging was 67 nm, increased 236 % when compared with the unaged composites. It was much higher than the rise of 70 % of the conventional curing epoxy composites after 18 h of hydrothermal aging while the interfacial thickness was 69 nm. Consistently, the average interfacial thickness of the fast and conventional curing epoxy composites determined by the adhesion were 68 nm (widened 247 %) and 68 nm (widened 67 %). In a word, the interfacial thickness of the fast curing epoxy composites was about 4 times than that of the conventional curing epoxy composites after 18 h of hydrothermal aging, because of the fast curing caused microcracks and flaws. Then, after 192 h of hydrothermal aging, the decreasing of short-beam strength of the fast curing epoxy composites were almost 1.6 times than that of the conventional curing epoxy composites, due to the faster growing of microcracks and delamination on the side surface of the fast curing epoxy composites short-beam samples during testing. Lastly, the maximum water absorption and diffusion coefficient of the fast curing epoxy composites were 1.2 % and 5.5 × 10−7 cm2/s respectively, which were both 1.3 times that of the conventional curing epoxy composites. Significantly, all the results proved that, attributing to the fast curing caused microcracks and flaws in the fast curing epoxy composites, through which water preferred to enter a composite along the fibers and interphase, the interphase in the fast curing epoxy composites were more sensitive to the hydrothermal aging than the conventional curing epoxy composites. Therefore, the water uptake, interfacial thickness and short-beam strength of the fast curing epoxy composites changed faster.

Novel stable aqueous emulsion of vinyl sizing agents for strong adhesion force between carbon fiber and vinyl resin

The sizing process is the best surface modification method to improve the interfacial properties of carbon fiber reinforced resin composites. In order to reinforce the interfacial adhesion of carbon fiber(CF)/vinyl resin (VE) composites, one novel emulsifying main slurry (NYDA) and resin (NE) were designed and synthesized from the view of the covalent bond between the CF and VE. The slurry NY-NE (2 wt% emulsion) exhibited excellent storage stability for three months. For introducing abundant active functional groups (C=C) to the NY-NE sized carbon fibers (NCF) surface, the interlaminar shear strength (ILSS) of NCF/VE composites (62.44 MPa) has increased by 69.31 % compared with unsizing carbon fiber (UCF)/VE composites (36.88 MPa). Moreover, the interfacial adhesion between CF and VE was also enhanced by the formation of C=C groups on the CFs surface to react with the VE effectively, which reinforced the interfacial layer to well transfer the load among the composite resin.

Evaluation of conductive smart composite polymeric materials for potential applicationsin structural health monitoring and strain detection

The presented work collects results from the evaluation of electrical response to mechanical deformation and formation of defects presented by different polymeric based composite materials with potential for applications in Structural Health Monitoring and Strain Detection. With the aim of showing the variety of key materials in sectors like civil aviation, wind energy, automotive or railway that present this ability, specimens of very different nature have been analyzed: a) thermoplastic commercial 3D printing filaments loaded with carbonic fillers; b) epoxy resin loaded with Carbon Nanotubes and c) long carbon fiber reinforced resin composite. Measurements of electrical properties of these materials were taken to evaluate their capability to detect the presence of structural defects of different sizes as well as its spatial location. On the other hand, simultaneous measurements of electrical resistivity and mechanical strain during tensile tests were performed to analyze the potential of materials as strain detectors. All composites studied have shown a positive response (modification of electrical performance) to external mechanical stimulus: induced damage and deformations.Graphical

Review of curing deformation control methods for carbon fiber reinforced resin composites

AbstractUnder the influence of extrinsic curing conditions and intrinsic properties of carbon fiber reinforced resin composites, the formation of curing deformation is inevitable, which makes the shape of the manufactured components differ from the designed structure, and even exceeds the assembly tolerance, resulting in the scrap of parts. Therefore, it is very urgent and important to optimize the curing deformation of carbon fiber reinforced resin composites. In this paper, the mechanism of stress and curing deformation is reviewed firstly, and then the factors affecting the curing deformation are summarized. In particular, from the point of view of materials in curing process, three curing deformation control strategies, including (i) reinforcement structure optimization, (ii) resin modification and process optimization, (iii) die surface compensation and tool‐part contact optimization, were proposed. And with the development of curing deformation simulation technology, the (iv) inverse design strategy before curing and (v) hot sizing method from the view of after cured were further put forward, respectively. By analyzing the link between processing details and curing deformation, it is found that the dominant factor affecting deformation may change under different conditions, so the interaction between factors needs to be further discussed. Subsequently, the effect of these distortion control methods on curing deformation was analyzed and evaluated, and the shortcomings were pointed out. Finally, the challenges existed in curing deformation research were identified, in order to contribute to the development of curing deformation research.

Integration 3D printing of bionic continuous carbon fiber reinforced resin composite

Inspired by microstructure characteristics of mantis shrimp propodus with high mechanical strength, the bionic continuous carbon fiber (CF) reinforced acrylonitrile butadiene styrene (ABS) resin composite with layered spiral structure was prepared successfully via self-built integration 3D printing. Combined with integration 3D printing demands of continuous carbon fiber reinforced ABS resin, bionic structure model was divided into 10 layers with cylindrical entities which spiralled from 0° to 45°. The 3D printed continuous carbon fibers realized designed specific arrangement direction in ABS matrix, which reappeared the layered spiral structure of mantis shrimp propodus. The existence of bionic layered spiral structure led to the higher tensile strength and impact toughness of bionic composite than that of ABS matrix and ABS/CF composite with unidirectional continuous carbon fiber arrangement via the mechanisms of fracture and pull-out of continuous carbon fibers. The high mechanical properties of integration 3D printed bionic composite proved the effectiveness and feasibility of 3D printing method and bionic layered spiral structure design, which extended the preparation method and application fields of carbon fiber reinforced thermoplastic resin composite in engineering materials.

Improvements of mechanical and tribological properties of carbon fiber reinforced composites via chemically grafting MA onto MnO2 nanosheets as interphase

To intensify the interfacial properties between carbon fiber (CF) and resin without sacrificing fiber, a new type of carbon fiber reinforced resin composite was designed and fabricated with MnO2 nanosheets and melamine (MA) as interphase. The MnO2 nanosheets were uniformly grown on the carbon fiber via hydrothermal method. And then MA was grafted on the MnO2 nanosheets to from chemical bond with resin by a simple bath shock method. The experiment results show that the flexural and tensile strength of the composite reinforced by CF-MnO2-MA increased by 24.1% and 14.5% compared to that of CF, respectively. And the wear rate is reduced by about 29.6%. In summary, the improvement of mechanical and frictional properties of the composite is related to the synergetic reinforcement in mechanical interlocking and chemical bonding of MnO2 nanosheets and MA.

Effects of key thermophysical properties on the curing uniformity of carbon fiber reinforced resin composites

AbstractKey thermophysical properties of the thermosetting resin, including density, conductivity coefficient and specific heat that evolve with resin curing, are related to temperature and curing degree fields of the fiber/resin composite material. However, their effects on heat transfer inside composite materials, consequently on the curing non-uniformity in thick-section laminates, are not well understood. The focus of this study is on the effects of key thermophysical properties of resin on the curing uniformity of AS4/3501-6 composite by means of the coupled thermochemical analysis with the method of numerical simulation. The results clearly indicate that the conductivity coefficient and specific heat of resin have obvious influence on curing uniformity, especially for thick laminates, while the density of resin has no noticeable effect on the curing uniformity. The simulation results can help to guide the material preparation of industrial production.

A new numerical model for the analysis on low‐velocity impact damage evolution of carbon fiber reinforced resin composites

ABSTRACTA new numerical simulation method was proposed to predict the mechanical behavior of carbon fiber reinforced resin composites under low‐velocity impact load. The impact damage evolution can be characterized in the form of energy dissipation which can be calculated through the new numerical model. The evolution mechanism of delamination was analyzed through distinguishing between the normal induced delamination and tangential slip induced delamination. The drop weight tests were conducted on composite laminates with five kinds of stacking sequence. Experimental analysis was also presented in this article. The damage area and distribution was investigated through ultrasonic C‐scan. The prediction had a good agreement with the experimental results through the comparison of impact response. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44374.

Integrated analysis on cure–microstructure–property–deformation correlation of carbon fiber reinforced resin composites

Curing process-induced deformation is one of the major problems that restrict the widespread use of carbon fiber/epoxy composites in aerospace industry. The principles involved in the generation of cure-induced stress in carbon fiber reinforced epoxy matrix laminates have received much interest in published literatures. A new analysis methodology that integrates the thermodynamic model, the curing kinetic model, the microstructural model and the stress–strain model is presented for simulating the curing process induced internal stress and deformation. By analyzing the curing behavior of carbon fiber/epoxy composites, the cure–microstructure–property–deformation correlation can be revealed, which does help in optimally designing the processing conditions in accordance with the specific needs for composite structures or properties. The simulation results of internal stress and deformation were in good agreement with the existing ones.

Flexural properties of polyethylene, glass and carbon fiber-reinforced resin composites for prosthetic frameworks

Objective. High flexural properties are needed for fixed partial denture or implant prosthesis to resist susceptibility to failures caused by occlusal overload. The aim of this investigation was to clarify the effects of four different kinds of fibers on the flexural properties of fiber-reinforced composites. Materials and methods. Polyethylene fiber, glass fiber and two types of carbon fibers were used for reinforcement. Seven groups of specimens, 2 × 2 × 25 mm, were prepared (n = 10 per group). Four groups of resin composite specimens were reinforced with polyethylene, glass or one type of carbon fiber. The remaining three groups served as controls, with each group comprising one brand of resin composite without any fiber. After 24-h water storage in 37°C distilled water, the flexural properties of each specimen were examined with static three-point flexural test at a crosshead speed of 0.5 mm/min. Results. Compared to the control without any fiber, glass and carbon fibers significantly increased the flexural strength (p < 0.05). On the contrary, the polyethylene fiber decreased the flexural strength (p < 0.05). Among the fibers, carbon fiber exhibited higher flexural strength than glass fiber (p < 0.05). Similar trends were observed for flexural modulus and fracture energy. However, there was no significant difference in fracture energy between carbon and glass fibers (p > 0.05). Conclusion. Fibers could, therefore, improve the flexural properties of resin composite and carbon fibers in longitudinal form yielded the better effects for reinforcement.

Chemical recycling of carbon fibers reinforced epoxy resin composites in oxygen in supercritical water

The carbon fibers in carbon fibers reinforced epoxy resin composites were recovered in oxygen in supercritical water at 30 ± 1 MPa and 440 ± 10 °C. The microstructure of the recovered carbon fibers was observed using scanning electron microscopy (SEM) and atom force microscopy (AFM). The results revealed that the clean carbon fibers were recovered and had higher tensile strength relative to the virgin carbon fibers when the decomposition rate was above 85 wt.%, although the recovered carbon fibers have clean surface, the epoxy resin on the surface of the recovered carbon fibers was readily observed. As the decomposition rate increased to above 96 wt.%, no epoxy resin was observed on the surface of the carbon fibers and the oxidation of the recovered carbon fibers was readily measured by X-ray photoelectron spectroscopy (XPS) analysis. The carbon fibers were ideally recovered and have original strength when the decomposition rates were between 94 and 97 wt.%. This study clearly showed the oxygen in supercritical water is a promising way for recycling the carbon fibers in carbon fibers reinforced resin composites.

Carbon fibre reinforced metals — a review of the current technology

The matrix of carbon-fibre reinforced resin composites limits their useful temperature of application to a maximum of about 300°C. Efforts have been made to increase the usable temperature of carbon-fibre composites by incorporating the fibres into metal matrices. This review describes the work in this area and covers aspects such as chemical compatibility between fibres and matrix, oxidation resistance, composite fabrication technology, mechanical properties and corrosion. At present, the results indicate that aluminium and aluminium alloys are the most promising metal matrices for structural applications. However, the poor impact resistance and corrosion resistance of the corresponding composites may be major limitations.