Recent advances of interphases in carbon fiber-reinforced polymer composites: A review

Excellent characteristics of carbon fiber-reinforced polymer (CFRP) include light weight, high strength, high modulus, and high temperature resistance. CFRP has a wide range of potential applications in the domains of public safety, aviation, and high-end non-military people products. Different methods have been used to modify the CFRP in order to increase surface action, harshness, and wettability, improving the interfacial binding between the fiber and network for better mechanical properties. Finally, a few CFRP-related difficulties are looked at, and future directions in interfacial support research are predicted. In this day and age, innovation-focused applications are becoming more significant, and the use of mechanical cycles is progressing swiftly and steadily. Due to their exceptional performance, such as low weight, high specific strength, and high specific stiffness, carbon fiber-reinforced polymer (CFRP) composites have a wide application viewpoint in the aerospace, military, and wind power sector high-quality civilian products. Currently, there is still a significant discrepancy between the theoretical calculation of the CFRP and the actual force. Improving the interface rationally is the key to solving this fundamental issue. The development, properties, and contemporary applications of CFRP composite materials, as well as their processing and boring activities, are discussed in this overview along with recent innovations and potential future applications.

In civil engineering, carbon fibre-reinforced polymer (CFRP) composites have emerged as a promising alternative to conventional materials. The article provides a comprehensive overview of the application of CFRP composites in various building structural elements and their characteristics and properties, such as their fatigue and corrosion resistance, stiffness and high strength, and incorporation of temperature factors. The advantages and disadvantages of CFRP composites and the current trends and prospects for CFRP composites in the construction sector are discussed. In addition, the article compares various studies on CFRP composites to shed light on their performance and potential limitations. This paper aims to provide useful information to researchers and practitioners interested in using CFRP composites in civil engineering applications. In addition, the article discusses emerging materials in CFRP, such as nanostructured carbon fibres, hybrid fibre reinforcement, and self-sensing CFRP. Additionally, the paper outlines how CFRP composites promote sustainability by increasing structural durability and longevity.

There are two major problems with fiber-reinforced polymer (FRP) composites during their machining that need to be addressed. The first concern is the delamination and formation of burrs at machined edges, and the second is the effects of aging leading to mechanical deterioration. In this study, carbon FRP (CFRP) and aramid FRP (AFRP) composites were manufactured by vacuum infusion method and aged for 2 years under natural environmental conditions. Piercing with three different clearances (1%, 5%, and 10% of sheet thickness) and speed of 4 m/s were performed. Additionally, conventional drilling was carried out at a feed rate of 0.2 m/min. The highest delamination factor difference between piercing and drilling processes was calculated as 7.3% and 13.9% for CFRP and AFRP, respectively. The highest burr amounts for AFRP and CFRP composites were obtained as 91.5% and 39% at 10% clearance for piercing process and 123% and 32.1% for drilling process, respectively. Compared with drilling, piercing generates less burr formation except for CFRP composites in the case of 10% clearance and more precise hole production. It is understood that piercing results significantly improve when smaller clearances up to 5% of the sheet thickness are utilized.

Carbon fiber-reinforced polymer (CFRP) composites are used in aerospace applications because of their superior mechanical properties and light weight. Avoiding damage in the machining of CFRP composites is difficult using traditional methods. Abrasive water jet (AWJ) has recently become one of the preferred machining methods for CFRP composites. This study evaluated the AWJ machinability of CFRP composites having three different fiber orientation angles (M1: [0°/90°]s, M2: [+ 45°/− 45°]s, and M3: [0°/45°/90°/− 45°]s) according to the delamination factor (Df), and the average surface roughness (Ra) as quality characteristics of the drilled holes. The aim of the study was to investigate the effects of different levels of AWJ drilling parameters on the delamination factor and surface roughness and to determine the optimum drilling parameter levels that provide minimum delamination formation and surface roughness values. For this purpose, AWJ drilling experiments were carried out using the Taguchi L16 (44) orthogonal array. Water pressure (WP), stand-off distance (L), traverse feed rate (F), and hole diameter (D) were chosen as process parameters. Analysis of variance was used to determine the percentage effects of the AWJ drilling process parameters. The microscopic surface roughness and delamination formation properties of the machined surfaces were revealed using a scanning electron microscope and an optical microscope, respectively. The most effective parameters on Df and Ra in the AWJ drilling of M1, M2 and M3 CFRP materials were determined to be water pressure, and stand-off distance. Minimum Df and Ra values were obtained when AWJ drilling the M3 CFRP composite with a fiber orientation angle of [0°/45°/90°/− 45°]s. Minimum delamination formation and very good surface quality can be obtained when the optimum process parameters determined in this study are used in the planning process for the AWJ drilling of CFRP composites having different fiber orientation angles.

CFRP (Carbon fiber reinforced polymer) composites are widely used in manufacturing industries since it offers attractive mechanical and physical properties like high strength, high modulus, and low density. Conventional drilling is an inevitable machining operation which is mostly performed for making hole in composites. In this study, CFRP composite was fabricated as a plate structure of 4 mm in thickness to investigate its drilling behavior. The drilling behavior was experimentally investigated through different drilling parameters. The effect of different drilling parameters namely axial feed (45, 63, and 90 mm/min), rotational speed for the spindle (250, 710, 2000 RPM), and three various geometries of the drill bits are analyzed on two machining characteristics one is torque other one is radial force and the last one is highest temperature during drilling of CFRP composites. The drilling parameters were also optimized through Taguchi technique. The relative significance of the drilling parameters was obtained by analysis of variance (ANOVA).

In the present work, first an attempt has been made to prepare carbon, glass and carbon-glass fibre-reinforced polymer composites, and later, machining of these composites is done on abrasive water jet machine (AWJM) to compare and optimize the machining parameters. Actually, the carbon fibre-reinforced polymer (CFRP) composites, glass fibre-reinforced polymer (GFRP) composites and carbon-glass fibre-reinforced polymer (CGFRP) composites are prepared through vacuum bagging process by using epoxy resin as the polymer matrix. The machining experiments are conducted to analyse the effects of the predominant machining parameters, i.e. cutting speed rate, feed rate and stand-off distance on the required machining characteristics, i.e. surface roughness (Ra), kerf top width (kw) and material removal rate (MRR). The range of values of each parameter is set at three different levels, and Taguchi’s L9 orthogonal array is used to design factors so that all the interactions between the response variables and machining variables can be investigated. Based on the experimental values, second-order regression equations are fitted between each of the response parameters and the machining parameters using Minitab 18 software. The equations are then optimized by defining the three equations of Ra, kw and MRR as the three objectives of a multi-objective optimization problem (MOOP) using a multi-objective optimization algorithm called Elitist Non-dominated Sorting Genetic Algorithm (NSGA-II). Single best compromise solutions with respect to the MOOPs of GFRP, CFRP and CGFRP composites are also determined from the Pareto optimal solutions obtained by NSGA-II. Finally, confirmation tests are conducted on specimens of GFRP, CFRP and CGFRP composites machined at their corresponding optimum parameters given by the GA. It is observed that the optimum values of Ra, kw and MRR of all the optimization problems are closer to the corresponding experimental values of confirmation tests.

Los polímeros reforzados con fibra de carbono (CFRP) son ampliamente utilizados en la industria aeroespacial debido a su excelente relación resistencia-peso. Sin embargo, la región interlaminar relativamente débil de la estructura laminada puede ocasionar fallos catastróficas y delaminación. Ante esto, la biomimética ha surgido como un nuevo enfoque para mejorar la tolerancia al daño de los CFRP. Entre los diferentes materiales biológicos, el nácar destaca por su balance entre tenacidad y resistencia. La razón detrás del rendimiento mecánico del nácar es su estructura discontinua jerárquica y multiescalar (conocida como "pared de ladrillo"). En este trabajo se implementan dos enfoques biomiméticos en materiales compuestos. En primer lugar, la introducción de una estructura de "pared de ladrillo" mediante la realización de cortes en los pre-impregnados que forman los laminados, dando como resultado "CFRP jerárquicos". En segundo lugar, la introducción de una escala adicional mediante la adición de nano-refuerzos (materiales relacionados con el grafeno, GRM), produciendo “CFRP multiescalares”. Finalmente, se desarrollaron “CFRP jerárquicos y multiescalares” mediante la combinación de ambos enfoques. Con el fin de evaluar la posible aplicabilidad y escalabilidad de dichas estructuras, los composites bioinspirados se han desarrollado utilizando procedimientos de fabricación y equipos ya existentes en la industria y usando materiales comerciales. En este trabajo se presenta una evaluación de dichos procesos de fabricación. Para los "CFRP jerárquicos", se ha investigado la influencia de la estructura de "pared de ladrillo" en el rendimiento mecánico de los materiales en términos de resistencia a la fractura y comportamiento a tracción. Asimismo, para los “CFRP multiescalares” se ha estudiado la influencia de la adición de GRM en sus propiedades físico-químicas y mecánicas. Finalmente, se evaluó la combinación de ambas estrategias para los “CFRP jerárquicos y multiescalares”. Los resultados mostraron una mejora en la tenacidad a la fractura y un cambio en el comportamiento de fractura de los compuestos mediante la implementación de tales estrategias. ----------ABSTRACT---------- Carbon fibre-reinforced polymers (CFRPs) are widely used in the aerospace industry because of their outstanding strength-to-weight ratios. They present high stiffness and low density for their high strength. Nevertheless, due to the relatively weak interlaminar region of the laminated structure, these materials present poor mechanical properties in the direction perpendicular to the fibres, leading to catastrophic failure and delamination. Biomimetics has arisen as an interesting approach to improve damage tolerance of CFRPs. Among the different biological materials, nacre stands out due to its toughness and strength balance. The reason behind the nacre’s mechanical performance is its hierarchical and multiscale discontinuous staggered structure (known as ‘brick-and-mortar’). In this work two biomimetics approaches are implemented into CFRP composites. First, the introduction of a ‘brick-and-mortar’ structure by performing specific cuts into the prepregs forming the composites, resulting in “hierarchical CFRPs”. Second, the introduction of an additional scale by the addition of nanoreinforcements (graphene-related materials, GRMs), producing “multiscale CFRPs”. Finally, “hierarchical and multiscale CFRPs” were developed by the combination of both approaches. In order to evaluate the potential applicability and scalability of such structures, the bio-inspired composites have been developed using manufacturing procedures and equipment already existing in the industry while using commercial materials. An evaluation of such manufacturing processes is presented in this work. For the “hierarchical CFRPs” the influence of the ‘brick-and-mortar’ structure in the mechanical performance of the composites has been investigated in terms of fracture toughness and behaviour under tensile loading. Similarly, for the “multiscale CFRPs” it has been studied the influence of the addition of GRMs on its physical-chemical and mechanical properties. Finally, the combination of both strategies was evaluated for the “hierarchical and multiscale CFRPs”. An enhancement in the fracture toughness and a change in the fracture behaviour of composites was obtained by implementing such strategies.

The use of carbon fiber-reinforced polymer (CFRP) composites having low weight and high strength provides the substantial energy savings in space and aerospace industry. The disadvantage of these composites is that the carbon fiber is not firmly bonded to the epoxy resin and the toughness of the produced materials is low. Graphene (G) and Graphene Oxide (GO) nanoparticles are used to functionalize CFRP composites. The CFRP composites functionalized with G and GO improve the strength of these composites by improving the fiber/matrix interface bond. In this study, the effect of type of nanoparticles, feed rate, cutting speed and number of flutes on machinability (cutting force, delamination factor and surface roughness) were experimentally investigated in the milling of CFRP composites, G-CFRP (CFRP functionalized with G) and GO-CFRP (CFRP functionalized with GO) nanocomposites. Cutting force, delamination factor, and surface roughness were found to be strongly impacted by feed rate, cutting speed, number of flutes, and type of nanoparticles. The increase in the number of flutes contributed to decrease of cutting force, delamination factor and surface roughness, while the increase in the feed rate caused to increase of them. By increasing cutting speed, surface roughness reduced, delamination factor and cutting force increased. In addition, compared to the CFRP composite, the cutting forces and surface roughness were higher, and delamination factor was lower in the CFRP composites functionalized with G and GO.

Composite materials have been extensively used in different fields due to their excellent properties, among which carbon fiber-reinforced polymer (CFRP) is the representative. Especially in high-precision fields, such as aerospace, CFRP has become the main structural material for some core components instead of metal. The particularity of such materials and their components in terms of structure, material properties, and required detection conditions puts forward more stringent and targeted detection requirements for detection technology. Ultrasonic testing technology as one of the important means of composite defect detection, which is derived from advanced nondestructive testing (NDT), has also been a rapid development. The propagation behavior and variation of ultrasonic waves in CFRP composites can reveal defects and damages in CFRP composites. Moreover, by constructing reasonable defect identification technology and detection technology, not only the qualitative and quantitative positioning analysis of defects and damages in CFRP composites can be realized but also the automatic, visual and intelligent NDT, and evaluation of CFRP composites can be realized. This paper mainly reviews the innovative nondestructive ultrasonic testing technology for CFRP composites and briefly introduces the research progress and application of this technology in CFRP defect detection. Finally, advanced nondestructive ultrasonic testing technology is summarized, and the problems and development direction of this kind of testing technology are put forward.

Carbon fibre-reinforced polymer (CFRP) composites have exceptional mechanical advantages such as high specific strength and stiffness, lightweight, and high damping capacity, making them very attractive for aircraft, aerospace, automotive, marine, and sporting applications. However, various defects such as delamination, burr formation, and surface roughness are observed during the drilling of CFRP composites, which are influenced by various drilling process parameters. In this work, the drilling quality of uni-directional CFRP composites. and the hybrid Al2O3 and hybrid SiC nano-composites are investigated experimentally using different types of drills such as step drill, core drill, and twist drill, as there is a limited study done on the comparative analysis of the impact of the above drills on the delamination factor and burr area on the above CFRP and hybrid nano-composites. The design of the experiment table was developed using response surface methodology (RSM) for input process parameters of spindle speed, feed, drill diameter, and drill type. The output surface characteristics (delamination factor and burr area) of the hole were measured quantitatively using the stereo zoom optical microscope. The main effect plots, contour plots, and analysis of variance (ANOVA) were used to examine the effect of spindle speed, feed, drill diameter, and drill type on exit delamination and burr formation. The analysis of main effect plots, contour plots, and analysis of variance showcased the optimum process parameters, such as a high spindle speed of 5500 rpm, low feed of 0.01 mm/rev, and drill diameter of 4 mm. The step drill demonstrated the least damage mechanism among drill geometries, followed by the twist and core drills. The minimum drilling damage was observed for the Al2O3 hybrid nano-composite compared to the neat CFRP composites.

Evaluation of hole quality to explore the influence of graphene nanoplatelets embedded in epoxy/carbon composite during abrasive water jet drilling

In this work, the effects of ZnO nanostructure‐surface functionalized carbon fibers has been examined along with their impacts on mechanical attributes of resulting hybrid carbon fiber reinforced polymer (CFRP) composites. The procedure involves hydrothermally generating ZnO nanostructures on carbon fibers. To generate hybrid composites, the modified carbon fiber fabric is then utilized as reinforcement in a matrix made of bisphenol‐A epoxy resin and polymer. The electron microscopy technique was employed to study development phenomenon of nanostructures on the fiber. According to the findings, lengthening the growth treatment and increasing seeding cycles improves the rate of ZnO formation. However, the results are not significantly impacted by the growth solution's concentration. The weight change analysis, X‐ray diffraction, Fourier transform infrared spectroscopy, UV‐spectroscopy, and energy dispersive spectroscopy all provide additional support for these conclusions. In comparison to plain CFRP composites, the developed hybrid CFRP composites tensile properties and impact resistance are significantly better. The ZnO‐modified CFRP composites exhibit improvements in elastic modulus, tensile strength, and in‐plane shear strength of up to 46.44%, 48.63%, and 20.79%, respectively. The hybrid composites' capacity to absorb impact energy also rises by 76%. Based on these results, the developed hybrid composites exhibit promising properties for applications in industries such as aircraft and automobile manufacturing. They offer high impact strength, high modulus, lightweight characteristics, and low void content, making them desirable materials for these industries.Highlights Controlled growth of vertically aligned ZnO nanostructures on fiber surface has been accomplished using hydrothermal method. Characteristics of CFRP composites such as tensile strength, elastic modulus, in‐plane shear strength, and impact energy absorption, were significantly enhanced on inclusion of ZnO. The developed hybrid composites offer cost‐effective solutions with improved mechanical properties. High impact strength and modulus make them suitable for applications in aircraft and automobile industries. Achieved exceptional morphological structure and enhanced surface‐to‐volume ratio.

In the current study, the low-velocity impact (LVI) characteristics of carbon fiber-reinforced polymer (CFRP), glass fiber-reinforced polymer (GFRP), and hybrid composites before and after the corrosive environment exposure were investigated. In this regard, CFRP, GFRP, and hybrid composites were subjected to LVI and tensile loadings after being kept in a 10% diluted HCl environment for 1 week and 1 month, and the impacts of the corrosive environment on the composites’ dynamic and mechanical responses were determined by comparing the outcomes of the control and aged specimens. LVI tests for CFRP, GFRP, and hybrid composites were carried out by transferring 25.2 and 11.2 J impact energy to the specimens with two impact velocities of 3 and 2 m/s, respectively, and thus, the effects of impact energy and hybridization were investigated. Moreover, tensile tests were conducted for the control and aged specimens with 2 mm/min crosshead speed, and thus, the effects of fiber material, hybridization, and corrosive environment on the mechanical properties were determined. The study found that CFRP composites had higher stiffness than GFRPs, whereas hybrid composites exhibited dynamic responses between CFRP and GFRP, as expected. On the other hand, it turned out that the composites absorbed most of the impact energy, which was interpreted as being absorbed by the damage of fiber-reinforced composites, which stand out with their brittle characteristics. Furthermore, it was discovered that the damage severity elevated as expected with a longer aging time, which was attributed to the corrosive liquid attacking the fibers, matrix, and fiber/matrix interfaces and reducing strength. It was also observed that, as predicted, the corrosive effects generally resulted in a reduction in tensile responses, including ultimate strain and tensile strength.

Carbon fiber-reinforced polymer (CFRP) is favored as the primary material for thin-walled components in fields such as aerospace due to its excellent properties, including light weight, high specific strength, high specific stiffness, and ease of integrated manufacturing. These thin-walled parts require assembly and connection with other components using rivets or bolts, necessitating the drilling of a large number of holes in CFRP. However, owing to its macroscopic heterogeneity, anisotropy, and low interlaminar bonding strength, CFRP is prone to defects during drilling, such as delamination, burrs, tearing, fiber pull-out, and surface voids. These defects can significantly compromise the connection quality and fatigue life of the components and may even lead to part rejection. To avoid drilling defects and achieve high-quality machining of CFRP, it is essential to fundamentally understand the intrinsic relationship between its material characteristics, such as anisotropy and interlaminar properties, and machining-induced damage. This paper systematically reviews the primary defects in CFRP drilling and their formation mechanisms, identifying drilling forces, drilling heat, and tool wear as the core contributing factors. Based on this analysis, various process optimization methods from different perspectives are proposed to mitigate these drilling defects and improve surface quality, including the optimization of cutting parameters, tool improvement, enhancement of the drilling environment, optimization of drilling process strategies, and the application of advanced drilling technologies. Finally, the paper summarizes the research on CFRP drilling and provides an outlook on future developments.

Effect of nanomaterial on mode I and mode II interlaminar fracture toughness of woven carbon fabric reinforced polymer composites