Properties Of Carbon Fiber Reinforced Composites Research Articles

Effect of Different Dielectric and Magnetic Nanoparticles on the Electrical, Mechanical, and Thermal Properties of Unidirectional Carbon Fiber-Reinforced Composites

Carbon fiber-reinforced particulate composites are immensely used in commercial and military applications due to their excellent functional and mechanical performance. Several studies have been reported to use nanofiller in carbon fiber-reinforced composites to improve their functional and mechanical performance. However, a comparative study was required to depict the best dielectric and magnetic nanofillers with excellent functional and mechanical performance. The current research was performed to compare the effect of different dielectric and magnetic nanoparticles on the electrical, mechanical, and thermal properties of carbon fiber-reinforced composites. The objective was to identify a nanofiller with excellent electrical, mechanical, and thermal properties with the same weight ratio and a potential candidate for EMI shielding application. Unidirectional composite prepregs containing 2% (by weight) of each magnetic and dielectric nanofillers were fabricated on an in-house developed lab-scale UD prepreg manufacturing setup. Among the dielectric nanofillers, the composite samples containing MWCNT nanofiller showed the highest electrical, thermal, and mechanical properties. The composite samples containing titanium oxide nanofillers showed better flexural, electrical, and thermal properties among magnetic nanofillers.

Infill Density Influence on Mechanical and Thermal Properties of Short Carbon Fiber-Reinforced Polyamide Composites Manufactured by FFF Process.

In three-dimensional (3D) printing, one of the main parameters influencing the properties of 3D-printed materials is the infill density (ID). This paper presents the influence of ID on the microstructure, mechanical, and thermal properties of carbon fiber-reinforced composites, commercially available, manufactured by the Fused Filament Fabrication (FFF) process. The samples were manufactured using FFF by varying the infill density (25%, 50%, 75%, and 100%) and were subjected to tensile tests, three-point bending, and thermal analyses by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). It was shown that the samples with 100% ID had the highest values of both tensile, 90.8 MPa, and flexural strengths, 114 MPa, while those with 25% ID had the lowest values of 56.4 MPa and 62.2 MPa, respectively. For samples with infill densities of 25% and 50%, the differences between the maximum tensile and flexural strengths were small; therefore, if the operating conditions of the components allow, a 25% infill density could be used instead of 50%. After DSC analysis, it was found that the variation in the ID percentage determined the change in the glass transition temperature from 49.6 °C, for the samples with 25% ID, to 32.9 °C, for those with 100% ID. TGA results showed that the samples with IDs of 75% and 100% recorded lower temperatures of onset degradation (approximately 344.75 °C) than those with infill densities of 25% and 50% (348.5 °C, and 349.6 °C, respectively).

Interfacial reinforced carbon fiber composites inspired by biological interlocking structure

SummaryWeak interfacial activity and poor wettability between fiber and matrix are known to be the two main factors that restrict the mechanical properties of carbon fiber-reinforced composites (CFRCs). Herein, inspired by high strength and toughness characteristics of wing feathers of Black Kite (Milvus migrans), natural hook-groove microstructure system (HGMS) and underlying mechanical interlocking mechanism were carefully investigated. Biomimetic HGMS based on dopamine-functionalized carbon fibers and ZnO nanorods were constructed successfully by a two-step modification method to enhance interfacial adhesion. Further, CFRCs featured with biomimetic HGMS were prepared by a vacuum-assisted contact molding method. Experimental results confirmed that flexural strength and interlaminar shear strength of the bioinspired CFRCs were effectively improved by 40.02 and 101.63%, respectively. The proposed bioinspired design strategy was proved to be flexible and effective and it was anticipated to provide a promising design approach and facile fabrication method for desirable CFRCs with excellent mechanical properties.

Magnetic graphene oxide/carbon fiber composites with improved interfacial properties and electromagnetic interference shielding performance

The poor interfacial properties of carbon fiber reinforced composites (CFRPs) limit their important applications in the aerospace industry. To address the shortcoming, magnetic graphene oxide (MGO) was prepared and encapsulated on the surface of carbon fibers to improve the interfacial properties of CFRPs. The existence of Fe3O4 on MGO reduced the agglomeration of graphene oxide, which made rapid and controlled sizing possible while still maintaining a good level of dispersion of MGO in the magnetic field. Results showed that the interlaminar shear strength, the interfacial shear strength, and the transverse fiber bundle tensile strength of the MGO treated CFRPs were 56.04%, 46.73%, and 82.00% higher than the untreated CFRPs, respectively. Meanwhile, MGO treated CFRPs achieved an electromagnetic interference (EMI) shielding effectiveness as high as 46.33 dB in X-band. This work provided insights into preparing structural–functional integrated CFRPs, which showed potential applications in the fields of aerospace, aeronautics, automotive among others.

Recovery of impact-damaged carbon fiber–reinforced composites using induction heating

Carbon fiber–reinforced composites (CFRCs) have been used extensively in structural applications within the aerospace and automotive manufacturing industries. However, several other applications have been recognized. These take advantage of the additional properties of CFRCs, which lead to providing better performance for structures. However, in their service environment, these CFRCs are inevitably susceptible to impact damage from multiple sources, and they must be able to recover from impacts to meet structural requirements. This study directs an experimental investigation of using induction heating (IH) for an impact-damaged CFRC. Here, IH process parameters, including the effects of electromagnetic frequency and generator power on the recovery of impact-damaged CFRC, have been analyzed. The anisotropic conductivity characteristics and the relationship between the drop-weight impact depth and conductivity of CFRC garnered much attention. This paper also offers the electromagnetic properties of CFRC for various applications. In this study, CFRC cured samples were obtained from Cetex® TC1200 PEEK, AS4 145 gsm, 16 unidirectional plies. Three variants of CFRC samples were tested: undamaged samples; samples with impact damage introduced in the center by a drop-weight impact test, according to the ASTM D7136/7136M standard; and samples with drop-weight impact damage recovered using the IH system. This work presents the results of the tensile strength of CFRC samples to assess the comparison of undamaged samples, samples damaged after the drop-weight impact test, and samples recovered after the drop-weight impact test. IH is appropriate for the recovery of impact-damaged CFRC samples, aiding in the conversion of electromagnetic energy to heat in order to generate mechanisms on components to recover the impact-damaged CFRC samples. Experimental results show that the impact-damaged area of the recovered CFRC samples is 37.0% less than that of damaged CFRC samples, and tensile strength results also improved after the impact-damaged CFRC samples were recovered. These results show that the IH method can effectively improve the impact damage performance of CFRC. The outcome of this study is promising for use in many applications, especially in the aerospace and automotive industries.

Biochar as an Effective Filler of Carbon Fiber Reinforced Bio-Epoxy Composites

The goal of this work was to investigate the effect of the biochar additive (2.5; 5; 10 wt.%) on the properties of carbon fiber-reinforced bio-epoxy composites. The morphology of the composites was monitored by scanning electron microscopy (SEM), and the thermomechanical properties by dynamic mechanical thermal analysis (DMTA). Additionally, mechanical properties such as impact strength, flexural strength andtensile strength, as well as the thermal stability and degradation kinetics of these composites were evaluated. It was found that the introduction of biochar into the epoxy matrix improved the mechanical and thermal properties of carbon fiber-reinforced composites.

Vibration Damping Mechanism of Fiber-Reinforced Composites with Integrated Piezoelectric Nanowires.

Here, both piezoelectric and nonpiezoelectric nanostructures are used within fiber-reinforced composites to improve the damping capabilities of the host material. This work investigates and isolates the role of both piezoelectricity and the mechanical redistribution of strain on the damping properties of fiber-reinforced composites through the integration of a nanowire interphase between the fiber and matrix. Prior works have successfully studied and reported the effectiveness of modifying the surface of the reinforcing fibers in a composite material using nanowires and other nanostructured interfaces to increase mechanical damping, however, have yet to fully investigate the mechanism dictating the observed behavior. This study analyzes the effects of nonpiezoelectric nanowire interfaces in comparison to piezoelectric nanowire interfaces of the same microscale morphology. The damping properties of carbon fiber-reinforced composites containing both sets of nanowires are investigated via dynamic mechanical analysis over a range of temperatures as well as modal analysis at the first resonant frequency. The results conclusively indicate that a combination of both mechanical and piezoelectric effects contributes to the significant increase in damping properties of fiber-reinforced composites and quantifies the individual contributions.

Influence of Carbon Roving Strain Sensory Elements on the Mechanical Properties of Carbon Fibre-Reinforced Composites

Over the last decade, carbon fibre-reinforced composites (CFRP) are increasingly used as lightweight material for various industrial applications. Due to the anisotropic material structure and its corresponding properties, novel design concepts and processing technologies were developed to further harness the material inherent lightweight potential. However, the material degradation in long-term use and failure behaviour is still considered a challenging issue for material scientists and engineers in particular. Therefore, concepts for structural health monitoring and their suitable implementation is still a major research topic. Among others, one solution uses the conductivity of carbon fibre yarns and their suitability to act as in-situ strain sensors. In the present work, the measurement principle bases on the usage of the piezo-resistive effect, meaning that every mechanical strain of the roving filaments causes a correlative change of the measurable electrical resistance. Since, these sensory elements need shielding from their surrounding carbon filaments of the composite structure, suitable fibre-based dielectric jackets have been developed with a wide range of suitable materials and textile processing technologies. In this contribution, the influence of the integrated carbon fibre sensors on the resulting mechanical performance of the composite structure is evaluated using an analysis of variances approach. Beyond that, the local composite morphology is analysed to evaluate the composite microstructure.

Effects of polycarbosilane interface on oxidation, mechanical, and ablation properties of carbon fiber-reinforced composites

Polycarbosilane (PCS) was introduced onto carbon fibers as an interface layer to meet requirements for using carbon fiber-reinforced phenolic resin composites (CPR) at high temperatures. Bending strength of as-received CPR with PCS (CPRS) was 541 ± 16 MPa, which is lower than that of pure CPR. However, because of protective PCS interlayer, the strength of CPRS after oxidation at 800 °C for 0.5 h was 112 ± 4.3 MPa, which is about 60% higher than residual strength of pure CPR after oxidation under the same conditions. Resulting protective interlayer of PCS at high temperatures leads to fracture toughness improvement of approximately 40% for CPRS. CPRS showed better ablation resistance under oxyacetylene flame than did pure CPR. Comprehensive protective effects from PCS interlayer and resulting improved thermal conductivity of CPRS account for enhanced ablation resistance.

Preparation and Characterization of Carbon Nanotubes/Carbon Fiber/Phenolic Composites on Mechanical and Thermal Conductivity Properties

The properties of fiber-matrix interface pay an important effect on the mechanical properties of carbon fiber-reinforced composites. To improve the interfacial properties in carbon fiber/phenolic resin (CF/PF) composites, CF adhered CNTs (CNTs-CF) were prepared by CVD method. The surface of treated CF and the distribution of CNTs in the interfacial region of CF were detected by scanning electron microscopy (SEM). SEM images identified 700[Formula: see text]C being the optimum growth temperature to obtain CNTs-CF, in which CNTs randomly dispersed surrounding the individual fiber surfaces. Compared to crude CF/PF composites, the tensile strength, bending strength, shear strength, impact strength, thermal conductivity at 25[Formula: see text]C of CNTs-CF/PF composites increase by 144.5%, 59.2%, 129.0%, 75.9% and 41.7%. The improvement of mechanical properties is due to that the homogenously dispersed CNTs serve as a supplementary reinforcement to the interface and further reduce inter-laminar stress concentration. This represents an important step toward CNT-reinforced polymers with high mechanical properties.

Effect of crystal morphology transition of polypropylene on interfacial properties of carbon fiber-reinforced composites through AlOOH surface treatment

Carbon fiber reinforced thermoplastics (CFRTPs) have many advantages, such as short processing cycle times, recyclability and design flexibility. However, CFRTPs have weak interfacial properties due to the non-polarity of carbon fibers. In this study, AlOOH surface treatment was applied on carbon fibers to improve the interfacial properties between the fiber and the matrix. The effect of the surface treatment on the crystal morphology of isotactic polypropylene (i-PP) at the interface was investigated by polarized optical microscopy (POM). The mechanical properties of fabricated CFRTPs were evaluated by measuring the interlaminar shear strength (ILSS). The ILSS of the AlOOH treated specimens after epoxy desizing increased by 106.8% compared with that of the untreated specimens.

Measurement and analysis of fiber-matrix interface strength of carbon fiber-reinforced phenolic resin matrix composites

Since fiber-matrix interface strength is critical to properties of carbon fiber-reinforced composites, measurement and analysis of interface strength are crucial steps in tailored design of composites. In the present work, the single fiber push-out test and the short-beam shear test were applied to measure the fiber-matrix interface strength in uni-directionally and two-directionally carbon fiber-reinforced phenolic resin matrix composites. The technical difficulties in processing the specimen and in realizing the fiber push-out were also discussed and clarified. For obtaining the successful test, typically, the thickness of the specimen should be smaller than 100 mm. During the fiber push-out, the de-bonding and fiber sliding at the interface were analyzed from the load-displacement curve features. The results indicated that both methods could be applied to determine the interface strength. The single fiber push-out and the short-beam shear tests resulted in a similar phenomenon in regard to the interface strength of uni-directionally and two-directionally carbon fiber-reinforced phenolic resin matrix composites, but expressed different values. The low interface strength measured from the short-beam shear test could be associated with multiple interlaminar shear failures. Furthermore, it was found that the interface strength of uni-directionally carbon fiber-reinforced phenolic resin matrix composites is somewhat higher than that of two-directionally carbon fiber-reinforced phenolic resin matrix composites. The difference in the interface strength could be attributed to the thermally induced residual stresses caused by the coefficient of thermal expansion mismatch of fiber and matrix. The approaches applied in the current work can be used for the evaluation of the interface strength of carbon fiber-reinforced phenolic resin matrix composites with different fiber-matrix bonding properties.

Dry fiber automated placement of carbon fibrous preforms

The superior material properties of carbon fiber-reinforced composites make them especially attractive for applications in aeronautics and aerospace industries. Cost reduction and time saving are continuously driving industry, leading to new industrial challenges which include manufacturing composite structures with optimal mechanical performances using the potential of advanced processes using robotics.To produce complex part shapes, technologies implying fabric draping in a mold imply large waste amount, fabric structure variability and uncertainties concerning local fiber volume fraction amount and thus final mechanical properties. To overcome such issues and comply with cost and time efficiency, automated dry fiber placement for preform manufacturing is proposed. This approach allows to integrate many functions in a complex part thank to the ability of the robot to steer fiber tows at specific locations. The final composite part is obtained by injecting the produced preform with resin using RTM (Resin Transfer Molding) or infusion process.The presented project aims to define the influence of the process driving parameters during fiber placement on the final preform properties range. Preforms were produced using a lab-scale automated placement demonstrator. Three preforms configurations were tested to highlight the influence of the preform structure on permeability and mechanical parameters through characterization of the compression behavior and permeability of the produced preforms. Choice of configuration will affect mechanical properties on the manufactured preforms, whereas creation of open channels to enhance the flow propagation during manufacturing does not necessarily increase the preform permeability.

Fatigue damage behaviors of carbon fiber-reinforced epoxy composites containing nanoclay

The effects of nanoclay inclusion on cyclic fatigue behavior and residual properties of carbon fiber-reinforced composites (CFRPs) after fatigue have been studied. The tension–tension cyclic fatigue tests are conducted at various load levels to establish the S-N curve. The residual strength and modulus are measured at different stages of fatigue cycles. The scanning electron microscopy (SEM) and scanning acoustic microscopy (SAM) are employed to characterize the underlying fatigue damage mechanisms and progressive damage growth. The incorporation of nanoclay into CFRP composites not only improves the mechanical properties of the composite in static loading, but also the fatigue life for a given cyclic load level and the residual mechanical properties after a given period of cyclic fatigue. The corresponding fatigue damage area is significantly reduced due to nanoclay. Nanoclay serves to suppress and delay delamination damage growth and eventual failure by improving the fiber/matrix interfacial bond and through the formation of nanoclay-induced dimples.

Hybrid composites based on polyethylene and carbon fibres Part IV Influence of hybrid design on impact strength

Hybrid composites possess unique features that can be used to meet different design requirements with respect to strength, stiffness and impact resistance. A key parameter in hybrid composite structures is the arrangement of fibres within the hybrid, as demonstrated by studies on hybrid systems based on carbon, glass or aramid fibres. It was shown that the hybrid design strongly affects a variety of flexural properties such as the modulus [1], strength [2], fracture energy [3-6] and fatigue behaviour [7]. Hybridization of relatively brittle carbon fibres with tough, high-performance polyethylene (HP-PE) fibres has proven to be highly effective in improving the impact properties of carbon fibre-reinforced composites [8-10]. By varying the HP-PE/carbon fibre ratio, laminate design and adhesion level of the HP-PE fibres, impact properties of such hybrid composites can be tailored to a specific application requiring either improved energy absorption or damage tolerance. Previous studies on layered HPPE/carbon hybrids were directed towards optimizing impact properties with respect to improved elastic energy absorption and enhanced damage tolerance [8, 10]. Related studies showed that intermingled hybrids, incorporating HP-PE fibres possessing low levels of adhesion exhibited a strong positive hybrid effect, i.e. a positive deviation from the properties predicted by the rule of mixtures, with reference to the total energy absorption under Charpy impact conditions [9]. These type of hybrids, exhibiting synergistic effects with respect to energy absorption, are quite promising for applications requiring kinetic energy dissipation such as crash-impacts. In this letter the influence of the fibre arrangement within the hybrid on this positive synergistic effect is discussed.

Strategic reinforcement of hybrid carbon fibre-reinforced polymer composites

A secondary fibre has been used to improve the impact properties of carbon fibre-reinforced composites. Steel wires possessing similar elastic properties to Type III carbon fibres have been added strategically to the composite cross-section. This has resulted in a 100% improvement in the fracture energy provided that the wires were placed in close proximity to the compressive or impacted face. Such a result is achieved with small increases in longitudinal and interlaminar shear strength. Only minor changes in specific properties occurred through the introduction of the high-density wires. The increase in fracture energy occurs because of the elimination of a compressive failure mode, believed to be brought about by the steel wires increasing the resistance to buckling at the impacted face. Hence, more energy-intensive processes, such as multiple delamination, fibre and wire pull out, are permitted to take place over larger areas of the fracture face.