Carbon Fiber Reinforced Plastic Composites Research Articles

Investigation of Fiber Orientation of Fused Filament Fabricated CFRP Composites via an External Magnetic Field

Abstract For carbon fiber-reinforced plastic (CFRP) composites, controlling the interior fiber distribution and orientation during the manufacturing process is a common approach to optize the structural performance of fabricated parts. However, few studies have been conducted to investigate fiber alignment during the additive manufacturing of CFRP composites. This study proposes a magnetic field controlled (MFC) method to control the fiber orientation during the fused filament fabrication (FFF) of nickel-coated carbon fiber (NCF) reinforced polymer composites. Firstly, a theoretical analysis model is established to explore the suitable magnetic field intensity for fiber rotation. Secondly, a customized FFF system with MFC components is implemented, and a polylactic acid matrix composite containing 10 wt% NCF is printed to validate the feasibility of the proposed approach. The microstructure of the printed samples is examined to assess the effectiveness of the method. Finally, uniaxial tensile tests are performed to investigate the impact of fiber orientation adjustment on mechanical properties. The experimental results reveal that the MFC method can effectively align the interior fiber orientation of CFRP composites, leading to a significant increase in the tensile strength (approximately 8.8%) and Young's modulus (around 10.5%) of the printed samples.

Barely visible impact damage detection in CFRP composite using vibrothermography with narrowband sweep excitation

The extensive use of carbon fiber-reinforced plastic (CFRP) composite materials in various industries has posed new challenges for conducting effective structural health monitoring and nondestructive evaluation techniques. Based on local defect resonance (LDR), the vibrothermography with narrowband sweep excitation is proposed to detect BVIDs in the CFRP composite. The response spectrum of displacement at the impact crater was collected by a laser Doppler vibrometer, which was used to determine the frequency range of narrowband sweep excitation. The frequency range was further validated by the analysis of local defect resonance for thermal responses, and the sweep duration was also optimized. Subsequently, the proposed vibrothermography was employed to detect BVIDs with varying severity. The impact damage could be efficiently activated and a significant temperature rise was generated in the defective areas, which enhances the temperature contrast of the thermal images and facilitates the quantification of defects.

Tensile strength prediction of unidirectional polyacrylonitrile (PAN)-based carbon fiber reinforced plastic composites considering stress distribution around fiber break points

Recent advancements in enhancing the mechanical characteristics of carbon fibers open up new application possibilities for carbon fibre-reinforced plastic (CFRP) composites. Particularly in unidirectional CFRPs, which form the basal structure of CFRP laminates, developing a micromechanics model capable of predicting the tensile strength of unidirectional CFRPs based on carbon fiber mechanical characteristics is a current aspiration. This study conducted a stress distribution analysis around the fiber fracture point to predict the tensile strengths of unidirectional CFRPs prepared with five types of polyacrylonitrile (PAN)-based carbon fibers, each with unique mechanical characteristics. Numerical simulation results obtained using a unidirectional CFRP model that considered the stress concentration, fiber axial stress, and bimodal Weibull distribution were reasonably consistent with the experimental results for the tensile strengths of unidirectional CFRP composites, regardless of the differences in the mechanical characteristics of the fiber. Our findings can provide guidance for designing further enhanced high-performance CFRP materials.

Multi optimization in slot milling of CFRP composites through grey relational- based Taguchi analysis

Carbon fiber-reinforced plastic (CFRP) composite materials are challenging to machine due to their anisotropy and heterogeneity. Thus, the experimental study of milling CFRP composite material is very crucial. In the current study, based on Taguchi’s L9 orthogonal array, slot milling experiments were performed on CFRP composite samples to make a decision on a parametric optimization of multiple responses such as material removal rate (MRR), delamination factor (Fd) and surface roughness (Ra) using grey relational-based Taguchi analysis. The selected milling parameters are cutting speed (A), feed (B), and depth of cut (C). Based on Grey Relational Grade (GRG), Analysis of Variance (ANOVA) was used to determine the parameters' significant contributions and the parameters' optimal levels. The results showed, with a 95% confidence level, that all of the chosen cutting parameters have a substantial impact on all of the measured responses. Based on a confirmatory test performed under ideal milling conditions, MRR has been increased with an improvement of 31.25 %, Fd has been decreased with an improvement of 1.66% and Ra has been decreased with an improvement of 28.3%. These improvements in all measured responses are equivalent to an improvement of GRG by 3%.

Effect of temperature and moisture composite environments on the mechanical properties and mechanisms of woven carbon fiber composites

AbstractTemperature and moisture are important environmental conditions governing the usage of carbon fiber‐reinforced plastics (CFRP). In this study, tensile, compression, and shear tests of woven CFRP composites were conducted in four composite environments: cold‐temperature dry state, room‐temperature dry state, elevated‐temperature dry state, and elevated‐temperature wet state. Fourier transform infrared (FTIR) spectroscopy was used to analyze the molecular composition and structure under these environments. The fracture morphology was also analyzed using scanning electron microscopy (SEM) to understand the deterioration mechanism of the material properties at the macro and micro scales. Finally, a two‐parameter Weibull statistical model was used to evaluate the scattering of the composites. The results demonstrate that the tensile, compressive, and shear properties of the material decrease under harsh conditions, and the degradation effect on the ultimate strength is much greater than that of the modulus. Cold‐temperature dry and elevated‐temperature wet conditions are particularly severe. Composite environments significantly affect the macroscopic failure process and ultimate failure mode of materials. In general, the temperature and humidity of the matrix system acts at the core of the deterioration mechanism of composites, affecting the properties of the fiber/matrix and orthogonal woven fiber interfaces, and eventually resulting in a loss of their constitutive strength and bearing capacity. The theoretical ultimate strength were consistent with the experimental values.Highlights Comprehensive mechanical property testing in multiple composite environments. Degradation mechanisms were revealed from multiscale morphology analysis. Scattering of composites were evaluated using statistical analyses. Cold temperature dry and elevated temperature wet were the worst states. Deterioration effect of environment on matrix and interface is the core failure mechanism.

Adaptive Machining Method for Helical Milling of Carbon Fiber-Reinforced Plastic/Titanium Alloy Stacks Based on Interface Identification.

CFRP/Ti stacks composed of carbon fiber-reinforced plastic composites (CFRP) and titanium alloys (Ti) are widely used in aerospace fields. However, in the integrated hole-making process of CFRP/Ti stacks, the machining characteristics of various materials are significantly different, and constant machining parameters cannot simultaneously meet the high-quality machining requirements of two materials. In addition, errors exist between the actual thickness of each material layer and the theoretical value, which causes an impediment to the monitoring of the machining interface and the corresponding adjustment of parameters. An adaptive machining method for the helical milling of CFRP/Ti stacks based on interface identification is proposed in this paper. The machining characteristics of the pneumatic spindle and the interface state in the helical milling of CFRP/Ti stacks are analyzed using self-developed portable helical milling equipment, and a new algorithm for the real-time monitoring of the machining interface position and adaptive adjustment of the machining parameters according to the interface identification result is proposed. Helical milling experiments were carried out, the results show that the proposed method can effectively identify the position of the machining interface with good identification accuracy. Moreover, the proposed parameter-adaptive optimized machining method for CFRP/Ti stacks can significantly improve hole diameter accuracy and machining quality.

Comparative performance evaluation between ta-C and TiAlCrN coated tools during milling of additively manufactured CFRP composite

Due to the excellent strength-to-weight ratio and corrosion resistance properties, the application of carbon fibre-reinforced plastic (CFRP) composites is rising among various industries day-by-day. This research addresses the performance evaluation of tetrahedral amorphous hard carbon (ta-C) and TiAlCrN coated carbide tools during milling of additively manufactured CFRP composite under dry environment. Tool rotational (spindle) speed, feed and depth of cut are considered as the variable factors in order to evaluate the machining performance characteristics in milling operation concerning surface roughness (Ra), cutting force (Fc) and cutting temperature (T). Taguchi's L16 orthogonal array design of experiments was adopted to conduct the machining trials under various settings of process variables. The relative influence of the different types of coatings and different operating parameters on machined surface morphology in milling was analysed by scanning electron microscope. From the experimental results, a promising machining performance is noticed for TiAlCrN coated carbide end milling tool accomplished by physical vapour deposition technique in terms of all machining attributes compared to ta-C coated end milling tool due to superior wear resistance, surface hardness and bonding strength of coating material. Among the tools used, TiAlCrN coated carbide tools for CFRP milling application promises excellent machinability performances in terms of reduced cutting force, enhanced machined surface morphology as well as surface finish, and minimum cutting temperature. The mean value ratios for Ra ta-C/RaTiAlCrN, Fc ta-C/FcTiAlCrN and T ta-C/TTiAlCrN are 1.44, 1.24 and 1.21, respectively.

Effects of Graphene Oxide Nanoparticles on Delamination in CFRP and Optimization Using Response Surface Modeling

AbstractCarbon fiber composites recently have captured the attention of many for their wide array of properties surpassing those of traditional metals. Carbon fiber‐reinforced plastic (CFRP) has several excellent properties like a high strength‐to‐weight ratio, better chemical resistance, and other strength characteristics. But one problem affecting the use of CFRP is its delamination. This occurs during drilling holes for various operations. It is a known fact that the aircraft industry is one such industry very much dependent on such drilling operations. Failures such as fiber rupture, surface irregularities, micro‐crack formation, and deformations around drilling regions are commonly encountered during the machining of CFRP composite. This research has studied the effects of graphene oxide nanoparticles on delamination in the drilling of CFRP composite. Carbon fiber is manufactured using a vacuum bag process. The optimum conditions for the drilling process are found by using response surface modeling (RSM) which leads to minimum delamination in CFRP fabricated.

The effects of support plate thickness on the drilling machinability of CFRP

When carbon fiber reinforced plastics (CFRP) are drilled, delamination damage occurs at the hole entry and exit. An important method to reduce delamination at the hole exit is using a support plate. Therefore, sustainable drilling of CFRP to reduce the delamination damage is promising for modern industries. In this study, the effect of drilling CFRP composite plates using support plates of different thicknesses on thrust force, delamination, and borehole surface quality was experimentally investigated. The results showed that the thrust force increased as the support plate thickness increased at low spindle speed, but the support plate thickness did not significantly affect the thrust force at high spindle speed. While severe delamination damage occurred at the hole exit in the tests without the use of support, delamination damage was significantly reduced in the case of using a support plate. On the other hand, the severity of the damages decreased as the support plate thickness increased, especially unless very high feed rates were chosen. Consequently, the thickness of the support plate considerably influences the damage formation and severeness of the damages is significantly reduced when a support plate with sufficient thickness is used.

Experimental investigations of impact behavior and milling performance of T700-CFRP under cryogenic conditions

The carbon fiber reinforced plastic (CFRP) composite is a reliable body material for modern airplanes, and extremely difficult to cut owing to its complex structure and special mechanical characteristics. In cutting CFRP, fiber breakage and delamination defects very frequently appear on the machined surface. The use of cryogenic cooling in CFRP cutting has proven to be an advanced approach to improving the machined surface quality of CFRP composites. To reveal the mechanism of milling CFRP under cryogenic conditions, this study investigates the impact behavior and cutting performance of T700-CFRP at low temperatures. The impact test of T700-CFRP unidirectional laminates with 0°, 45°, and 90° fiber directions was performed at various temperatures ranging from 20 °C to −196 °C, to analyze the impact toughness and the fracture morphology. Side milling experiments of CFRP laminates of 0°, 45°, and 90° fiber directions with the PCD endmill were conducted at the same temperatures used in the impact test. Experimental findings revealed that for 0° specimens, the impact toughness increased at lower temperatures, and the impact damage worsened as the temperature dropped from −120 °C to −196 °C. There were no evident changes in the impact toughness or impact damage of 45° and 90° specimens with the decrease in temperature. The feed force and radial force increased as the cooling medium temperature lowered during milling CFRP. The machined surface of 45° workpieces was the roughest among all the workpieces and covered with numerous pits and craters. The machined surface roughness Ra of 0° workpieces decreased as the cooling medium temperature was lowered from 20 °C to −160 °C and then increased at −196 °C, while the Ra value of both 45° and 90° workpieces rose as the temperature dropped from 0 °C to −196 °C.

Axial quasi-static crushing of composite tubes: An investigation on the influence of the modeling techniques

Carbon fiber-reinforced plastic (CFRP) composites perform remarkably as crashworthy structures in transport vehicles. They promise to improve the crashworthiness of vehicles in addition to weight savings thanks to their superior strength-to-weight ratio. However, designing composite crashworthy structures is challenging since predicting the energy absorption values and crushing behavior are not straightforward. Finite element modeling is a very effective numerical technique to predict energy absorption values and shorten the design process of composite structures, yet it is also quite hard to simulate the crushing of composite structures due to their complex damage mechanisms. This paper presents an investigation of the axial crushing behavior of composite tubes made of woven fabric CFRP and the influence of the different modeling techniques. Macro-scale stacked shell modeling approach is adopted to model the composite tubes. Various virtual debris wedge models are incorporated to obtain realistic failure modes in simulations. Simulated crushing morphologies and energy absorption values are compared with the experimental test results. Furthermore, the prediction capability of the models and the influence of mesh geometry used for rigid flat platen crushers are examined. It is found that the geometry of the virtual debris wedge and mesh geometry of the flat platen crusher affect the simulated crushing modes and level of the absorbed energy predicted.

Taguchi analysis of the tensile behaviour of unaged and hygrothermally aged asymmetric helicoidally stacked CFRP composites

Taguchi method was used to predict and optimize the effects of hygrothermal aging on the tensile behavior of asymmetric helicoidally stacked Carbon Fiber Reinforced Plastic (CFRP) composites. This research is in furtherance to the previous work, which dealt purely with experiments. MR70 12P carbon fiber epoxy prepreg sheets were manufactured into laminated composites comprising constant inter-ply pitch angles ranging from 0o to 30o. The composites were tested in tension as either dry unaged specimens or following hygrothermal aging in seawater at the constant temperatures of 40 oC and 60 oC for 2000 hrs. Optimizations were conducted based on Taguchi L18 orthogonal array considering two design parameters viz. inter-ply stacking angles and hygrothermal aging temperature. The result depicted that the combination of aging temperature (C) and stacking angles are major factors in determining the tensile behavior of composite materials (p = 0.011). The model explains 86.6% of tensile strength variability, with a predicted R-squared value of 93.04%. The model’s robustness is supported by the adjusted R-squared value of 77.6%. Analysis of variance shows that inter-ply stacking angles are the main significant factor affecting the tensile behaviors at a 95% confidence level. A confirmation test was carried out to validate the optimized results and it was found that there were improvements in S/N ratios from initial to optimal setting.

Optimization of viscoelastic behaviors of bioinspired asymmetric helicoidal CFRP composites using Taguchi Method

The dynamic mechanical properties play an important role in the selection of suitable materials in the manufacturing wing of aircraft and wind turbine blades. In this paper, the standard Taguchi method was used to examine the effect of inter-ply stacking angles of 0° (UD), 0/90° (cross-ply), 5°, 15°, 10°, 20°, 25° 30° and aging temperature (ambient temperature, 40o, 60o) on the dynamic mechanical properties of bioinspired asymmetric helicoidal Carbon Fiber Reinforced Plastic (CFRP) composites. The standard Taguchi’s L18 was used. The signal-to-noise ratio and analysis of variance were introduced to analyze and estimate the optimal combination parameters. The results show the dynamic mechanical properties are linearly correlated to the fiber architecture and aging temperature. Analysis of variance (ANOVA) indicates that inter-ply stacking angles (15°, and 20°) and aging temperature (40o, 60o) are the main significant factors affecting the dynamic mechanical values at a 95% confidence level. Inter-ply stacking angles are finally noted as critical factors affecting the extent of macromolecular mobility within helicoidally stacked continuous fiber CFRP composites. A confirmation test validated the optimized results and it was found that there were improvements in S/N ratios from initial to optimal setting. The experimental and expected results are very close, with an error ratio not exceeding 5%.

SiO nanoparticle modified CFRP composites effecting on mechanical and vibration damping properties

AbstractSiO nanoparticle inclusion effects on vibration‐damping and mechanical properties of carbon fiber reinforced plastic composites (CFRP) were experimentally investigated by incorporating the NS particles into the epoxy resin system. The nanoparticles in the SiO form were incorporated into the epoxy resin at different ratios (0.5%, 1%, 1.5%, 2%, and 3%) in weight to produce the modified CFRP samples. In addition, the effects of cutout with two different types (edgewise semicircular and central circular) on the vibration response of SiO modified CFRP test samples were determined for different SiO particle incorporation ratios. In this way, variation of both mechanical and vibration properties was experimentally determined in terms of cutout weakening of the composite in the middle while incorporating the SiO particle modification of the CFRP composites. It was seen from this study that the incorporation SiO nanoparticles into CFRP composites were provided the increasing trend in the vibration‐damping and mechanical properties and the highest mechanical and vibration properties were obtained for the addition of 1.5 wt% SiO nanoparticles. On the other hand, further SiO nanoparticle addition, more than 1.5–2 wt%, decreased in mechanical and vibration properties of the composite test samples.Highlights SiO nanoparticle effects on mechanical properties of CFRP composite laminates. SiO nanoparticle effects on vibration damping of CFRP composite laminates. Central cutout effects on vibration characteristics of CFRP composite laminates. Fracture characteristics of CFRP composite laminates with SiO nanoparticle incorporation.

Effects of fiber orientations on fracture mechanisms in rotary ultrasonic drilling of carbon fiber reinforced plastic laminates

The fracture mechanisms of the carbon fibers seriously depend on fiber orientations which significantly influence the surface quality of carbon fiber reinforced plastics (CFRPs). Rotary ultrasonic drilling (RUD), possessing some excellent characteristics including the superior sidewall quality and high cylindricity error, offers a possibility for the efficient drilling of the CFRP components. In contrast, the effects of fiber orientations on fiber fracture mechanisms are still not fully recognized in RUD of CFRP composites. Incorporated with kinematic characteristics of the abrasive, a novel theoretical model was developed to quantitatively describe the effective orientation of the fiber. Afterwards, the drilling experiments with and without ultrasonic were conducted under the same parameters. The surface topographies of the hole sidewalls at various orientations were comparatively characterized to explore the fiber fracture mechanisms. Subsequently, the influences of these mechanisms and the drilling parameters the surface qualities were also investigated. Moreover, the bending failure mechanisms of the carbon fibers were explored through theoretical analysis. As a result, another fiber fracture mechanism, bending failure, was identified with the smooth fracture and micro-fragmentation topographies at upwind and leeward parts of the fiber cross-section, respectively. Ultrasonic superimposition by means of the immense inertia force of the abrasive promoted the micro-fracture of the carbon fiber. The weaker sustainment from the back-up materials brought about the serious bending failure of fiber oriented at 135°, while the axial load component aggravated the tensile fracture of the carbon fiber with the effective orientation of 45°. The critical moment of the fiber bending failure was also established, by incorporating the beam theory and linear elastic fracture mechanics. The fundamental investigation provided a favorable foundation for further optimizing the parameters to improve the drilling quality and efficiency in formal RUD of CFRP composites.

Influences of Main Machining Process Parameters and Tool Wear on The Machining Damage Generated During Edge Milling CFRP Composites

Machining Carbon Fibre Reinforced Plastics (CFRPs) composites are typically accompanied by the appearance of machining damage which strongly impacts the structural integrity of composite parts during their service lives. Studying the correlation between machining damage and its affected factors has still been an open issue. Hence, it is necessary to do more research. This study focuses on investigating the influences of main process parameters and tool wear phenomenon in terms of machining length on the machining quality which was characterized by the surface roughness criterion, the ten-point max, Rz. A full factorial design of experiments was conducted including three levels of feed speed and two degrees of spindle speed. The results revealed that machining damage was mainly influenced by process parameters at a small machining distance, whereas at a longer machining distance, tool wear had a dominant effect on the machining quality than machining parameters. These findings could provide guidelines for selecting suitable machining parameters to enhance the machining quality of CFRP.

An anti-wear tool structure with integrated-micro hybrid cutting edges for milling of carbon fiber–reinforced plastics composites

An anti-wear tool structure with integrated-micro hybrid cutting edges for milling of carbon fiber–reinforced plastics composites

Effect of printing parameters on 3D-printed carbon fiber-reinforced polymer composites under magnetic field control

Magnetic field controlled (MFC) 3D printing is a promising method for realizing the intelligent control of the structural performance of carbon fiber-reinforced plastic (CFRP) composites by adjusting the fiber orientation during the printing process. However, few studies have focused on the influence of the printing parameters on the magnetic control of the fiber direction. Therefore, in this study, the mechanical properties and internal fiber distributions of MFC 3D-printed samples of CFRP composites with 10 wt% fiber content, which were printed at different speeds and layer thicknesses, were investigated. Subsequently, the effects of the fiber content on the mechanical properties and fiber distribution of the MFC 3D-printed samples were studied. The origin of fiber fracture was evaluated through observation and analysis of the fracture section using scanning electron microscopy. The fiber orientation could be well adjusted under the action of a magnetic field and adjustment of printing parameters, thereby improving the tensile strength, young's modulus significantly with slightly decrease of fracture elongation. The recommended parameter combinations (printing speed and layer thickness) were 40 mm/s and 0.2 mm for 10 wt% fiber content CFRP composites.

An Application of Data Envelopment Analysis in the Selection of the Best Response for the Drilling of Carbon Fiber-reinforced Plastic Composites

In the drilling operation, defects such as delamination at exit and entry are very disturbing responses that impact the efficiency of the drilling process. Without control, an exponential growth in the amount of drilled components with defect quantities may result. Thus, the process engineer has input in attaining the desired production levels for components in the drilling process. Consequently, this article deploys a novel method of data envelopment analysis to evaluate the relative efficiency of the drilling process in reducing the defects possible in the producing components from the CFRP composites. The high-speed steel drill bits were utilized to process the CFPs, while the responses considered are the entry and exit determination, thrust force, and torque, among others. Literature experimental data in twenty-seven experimental counts were summarized into fewer groups and processed through the data envelopment analysis method. The results show that capturing the CFRP composite responses is feasible, providing an opportunity for enhanced efficiency and a situation where undesirable defects in the CFRP composite production process may be eradicated. The article’s uniqueness and primary value are in being the foremost article in offering an updated vast representation of the comparative efficiency of CFRP composite parameters within the literature for the composite area. The work adds value to the CFRP composite literature by envisaging and understanding the comparative efficiency for the parameters, identifying and separating the best from the worst decision-making unit. It also reveals how the parameters are linked by their relative placements. The article's novelty is that using data envelopment to compare the efficiency in reducing drilling defects such as entry and exit determination, among others. The method’s utility is to provide information for cost-effective drilling operations during the planning and control phases of the operation.

High performance drilling of T800 CFRP composites by combining ultrasonic vibration and optimized drill structure

Drilling of high-strength T800 carbon fiber reinforced plastic (CFRP) are widely employed in current aviation industry. Drilling-induced damages frequently occur and affect not only the load carrying capacity of components but also the reliability. As one of effective methods to reduce the drilling-induced damages, advanced tool structures have been widely used. Nevertheless, it is still difficult to realize high machining accuracy and efficiency by this method. This paper compared three different drill bits to evaluate the drilling performance of T800 CFRP composites and the results showed that the dagger drill was a good choice to drill T800 CFRP considering the lowest thrust force and damages. On this basis, ultrasonic vibration was successfully imposed on dagger drill to further improve the drilling performance. The experimental results showed that ultrasonic vibration reduced the thrust force and surface roughness with a maximum decrease of 14.1 % and 62.2 % respectively. Moreover, the maximum hole diameter errors were decreased from 30 μm in CD to 6 μm in UAD. Besides, the mechanisms of force reduction and hole quality improvement by ultrasonic vibration were also revealed. The results suggest that the combination of ultrasonic vibration and dagger drill is a promising strategy for high performance drilling CFRP.