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.

An Experimental Procedure to Study the High-Speed Orthogonal Cutting of Unidirectional GFRP

The aim of this paper is to establish a valid procedure for better understanding all of the phenomena associated with the high-speed machining of glass fiber-reinforced plastic (GFRP) composites. Both rectangular and circular specimens were machined at high cutting speeds (up to 50 m/min) in order to understand what occurred for all values of fiber orientation angles during machining operations. An innovative testing methodology was proposed and studied to investigate the phenomenon of burr formation and thus understand how to avoid it during machining operations. To this end, the forces arising during the machining process and the roughness of the resulting surface were carefully studied and correlated with the cutting angle. Additionally, the cutting surface and chip morphology formed during cutting tests were examined using a high-speed camera. Close correlations were found between the variations in the cutting forces’ signals and the trends of the surface roughness and the morphology of the machined surface.

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.

Micromechanical Analysis of GFRP Composite with Micro-Level Defects

Fiber-reinforced plastic (FRP) composites are subjected to micro-level defects such as fiber-matrix debond and/or matrix cracks after a period of their service due to the increasing brittleness of matrix material. Prediction of the degraded elastic properties of a lamina through micromechanical studies by incorporating micro-level defects gives an idea of the health condition of such structures. Due to the limitations of classical mathematical approaches in solving complex structures, numerical mathematical methods like the finite element method (FEM) can be employed. The present investigation deals with the micromechanical analysis of Glass fiber-reinforced plastic (GFRP) composite with micro-level defects to predict some of the elastic properties. The composite is idealized as an array of square unit cells, and the micromechanical behavior of one such unit cell is simulated in ANSYS software using the three-dimensional finite element method to predict Young’s moduli and Poisson’s ratios in principal material directions. The converged finite element solution for longitudinal modulus is validated by the rule of mixtures and the other properties using the Maxwell–Betti reciprocal theorem. Variations of Young’s moduli and Poisson’s ratios due to an incremental internal failure of composite such as low-level, medium-level, and high-level defects at an expected range of fiber volume fractions (50% - 60%) are evaluated and estimated the percentage degradation with respect to a corresponding defect-free composite.

Mechanical and electrical performance of glass fiber reinforced plastic insulation for cryogenic application in fusion magnet irradiated in fast breeder reactor

In a superconducting (SC) magnet fusion reactor, the insulation material used has to withstand significant fluxes of neutrons and neutron-induced gamma radiation. Epoxy-based glass fiber-reinforced plastic (GFRP) composites are the insulation system for fusion magnets and are highly demanding. This insulation system requires excellent mechanical and electrical performance under mixed neutron and gamma radiation at cryogenic temperatures. The insulation material developed consists of boron-free S-glass fiber impregnated with a two-component modified Diglycidyl ether of Bisphenol-A (DGEBA) epoxy resin. An anhydride-cured DGEBA resin system is not suitable for cryogenic temperatures. Therefore, to overcome this thermal stress issue in cryogenic components of SC magnets, a high-toughness, flexible, aromatic amine-cured epoxy resin system was developed for the insulation system. In order to assess the radiation resistance for mechanical and electrical properties, the composite samples were irradiated in the fast breeder test reactor (FBTR) at IGCAR, Kalpakkam, India. The irradiation experiment was carried out for a neutron fluence of 1.0E+21 n/m2 and a gamma dose of 0.4 MGy at a full reactor power of 32 MWt. The tensile strength, interlaminar shear strength, and breakdown strength measurements were investigated before and after irradiation at room temperature and 77 K. The test results indicate that no significant degradation was observed in the properties of the irradiated samples up to the above-mentioned radiation doses.

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 on hybridization of interlayer composites and self-reinforced polypropylene

In recent years, there has been increasing attention to develop a high-strength, lightweight composite as a potential substitution for conventional materials in various sectors, whereby most studies have focused on the mechanical performances of fibre-reinforced plastic (FRP) such as carbon, glass and aramid. In contrast, the hybrid composites are less common, though are viewed to have substantial potential in terms of flexibility and capability to merge the benefits of different composites. In this study, five composite designs consisting of several types of woven fibres and self-reinforced polypropylene (SRPP) sheets have been fabricated using the hand lay-up procedure. Several designs are arranged based on the interlayer hybridization mode. The static mechanical properties of the composite designs were examined through the standard tensile and three-point flexural tests. The outcomes attained from the experimental works revealed that carbon fibre-reinforced plastic (CFRP) produced the best tensile characteristics. The CFRP structure displayed 46% higher tensile strength and a 33% greater elastic modulus compared to the CAFRP specimen. Meanwhile, hybrid carbon/aramid fibre-reinforced plastic (CAFRP) pointedly enhanced flexural properties in comparison with single type and other hybrid composites, whereby CAFRP structure outperformed the CFRP structure, exhibiting superior results with variations of 50% and 19% in flexural strength and modulus, respectively. Though the inclusion of SRPP layers in-between the hybrid setup exhibited a decrease in both tensile and flexural strength, but improved the total strain level. The evidence from this study suggests that FRP composites indicate structures of high strength and stiffness but low elongation, whereas SRPP-based composites improve toughness but reduce stiffness characteristics.

Textile-based piezoelectric impact sensors for fibre-reinforced plastic composites

Abstract Bird strikes on wind turbine rotor blades have long-term impacts on fibre reinforced plastic composites. To monitor and document these impacts, integrating sensors into the composite structure is necessary. However, conventional sensors introduce foreign objects that deflect the fibre orientation, weakening the composite and potentially causing damage like delamination. To address this, silver-coated glass fibre sensors have been developed and integrated into the composite structure. Impact tests confirmed the functionality of the developed sensors. These sensors seamlessly integrate into the reinforcing structure due to their textile nature and multi-layered fibre structure. Unlike conventional sensors, they do not introduce foreign objects or create mechanical weak spots. Instead, they are expected to contribute to the overall stability of the component. In summary, integrating impact sensors into fibre reinforced plastic composites is crucial for documenting bird strike damage. Conventional sensors weaken the composite, but silver-coated glass fibre sensors resolve this issue by seamlessly integrating into the structure, enhancing stability and durability.

Effect of Microstructure on the Machinability of Natural Fiber Reinforced Plastic Composites: A Novel Explainable Machine Learning (XML) Approach

Abstract Natural fiber-reinforced plastic (NFRP) composites are ecofriendly and biodegradable materials that offer tremendous ecological advantages while preserving unique structures and properties. Studies on using these natural fibers as alternatives to conventional synthetic fibers in fiber-reinforced materials have opened up possibilities for industrial applications, especially for sustainable manufacturing. However, critical issues reside in the machinability of such materials because of their multiscale structure and the randomness of the reinforcing elements distributed within the matrix basis. This paper reports a comprehensive investigation of the effect of microstructure heterogeneity on the resultant behaviors of cutting forces for NFRP machining. A convolutional neural network (CNN) links the microstructural reinforcing fibers and their impacts on changing the cutting forces (with an estimated R-squared value over 90%). Next, a model-agnostic explainable machine learning approach is implemented to decipher this CNN black-box model by discovering the underlying mechanisms of relating the reinforcing elements/fibers’ microstructures. The presented xml approach extracts physical descriptors from the in-process monitoring microscopic images and finds the causality of the fibrous structures’ heterogeneity to the resultant machining forces. The results suggest that, for the heterogeneous fibers, the tightly and evenly bounded fiber elements (i.e., with lower aspect ratio, lower eccentricity, and higher compactness) strengthen the material and thereafter play a significant role in increasing the cutting forces during NFRP machining. Therefore, the presented framework of the explainable machine learning approach opens an opportunity to discover the causality of material microstructures on the resultant process dynamics and accurately predict the cutting behaviors during material removal processes.

Towards understanding the material removal mechanism on the effect of ultrasonic vibration and anisotropy for unidirectional CFRP by scratching

Rotary Ultrasonic Machining (RUM) is a well-known non-traditional machining method for hole-making and surface grinding of Carbon Fiber Reinforced Plastics (CFRP). However, the complicated material removal behavior of CFRP is difficult to understand due to its heterogeneity and anisotropy resulting from components and the nature of laminated structures. In this concern, we conducted ultrasonic vibration-assisted scratching (UVAS) to understand the material removal mechanisms with the effect of ultrasonic vibration and fiber anisotropy. Based on scratching morphology, the removal behavior of unidirectional CFRP (UD-CFRP) varied in different scratching directions. Meanwhile, the addition of ultrasonic vibration could suppress machining damage generated by the scratching process. The motion trajectory analysis and experimental results show that the ultrasonic vibration-assisted scratching load is smaller under the same machining parameters. Discussions on the material removal mechanism of UD-CFRP during the effect of ultrasonic vibration and fiber anisotropy were also provided. This research will contribute towards an in-depth understanding of the material removal mechanism for fiber reinforced plastics composites in RUM, which will be useful in optimizing the application of ultrasonic vibration assisted processes for advanced composites machining.

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.

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

Mechanical properties and failure mechanism analysis of basalt-glass fibers hybrid FRP composite bars

In order to solve the defect of insufficient performance of the single fiber reinforced plastic (FRP) bars. The basalt fibers and glass fibers are prepared into the basalt-glass fibers hybrid FRP composite bars (B/G hybrid FRP bars) in this paper. The failure mechanism of basalt-glass fibers hybrid FRP composite bars is analyzed by the finite element method. The main failure factors include not only fiber breakage but also the separation of the interface between the two fibers. The mechanical properties of basalt-glass fibers hybrid FRP composite bars in the alkaline environment are predicted by simulation. The tensile properties, elongation properties, pseudo ductility stage length, and yield stress reduction of basalt-glass fibers hybrid FRP composite bars under different fiber volume ratios are investigated by tensile tests. The results show that when the volume ratio of glass fiber to basalt fiber is 7:3, the ultimate strain reaches 2.57%. When the volume ratio of glass fiber to basalt fiber is 9:1, the ultimate strain reaches 3.06%, with a difference of 0.49%. In addition, the yield stress reduction stage in basalt-glass fibers hybrid FRP composite bars is also affected by the volume ratio of hybrid fibers. When the volume ratio of glass fibers to basalt fibers is 9:1 and 7:3, the difference in ultimate tensile strength and the difference in yield stress reduction stage of the two are 185.85 MPa and 145.09 MPa, respectively. In addition, the optimal volume ratio range suitable for different situations is summarized in the study. When glass fiber accounts for 68.9–100% of the total integral number of basalt-glass fibers hybrid FRP composite bars, the tensile and extension properties of basalt-glass fibers hybrid FRP composite bars have different degrees of change.

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.

Additively manufactured cure tools for composites manufacture

This research presents a novel framework for the design of additively manufactured (AM) composite tooling for the manufacture of carbon fibre-reinforced plastic composites. Through the rigorous design and manufacture of 30 unique AM tools, the viability of a design for AM framework was evaluated through measuring the performance with respect to geometrical accuracy and thermal responsiveness, and simulating the tool specific stiffness. The AM components consisted of a thin layup facesheet, stiffened by a low density lattice geometry. These tools were successfully used to layup and cure small composite components. The tooling was highly thermally responsive, reaching above 93% of the applied oven heating rate and up to 17% faster heating rates compared to similar mass monolithic tools. The results indicate that thermal overshoot has a greater dependence on the lattice density while the heating rate was more sensitive to the facesheet thickness. Lattice densities of as little as 5% were manufactured and the best overall geometry was a graded gyroid lattice with thicker walls near the surface and thinner walls at the base, attached to a 0.7 mm thick facesheet. The outputs from this research can provide a new route to the design and manufacture of mould tools, which could have significant impacts in the composites sector with new, lighter, more energy efficient tooling.

KEKUATAN LENTUR KOMPOSIT MENGGUNAKAN MATRIKS EPOXY DENGAN REINFORCEMENT BAMBU, CARBON, PALF DAN SERAT BUNGA MALVA

The flexural strength comparasion of epoxy matrix composite with diferent reinforcement . Composite is a combination of two or more materials that have good physical properties and good mechanical properties. Reinforcement materials commonly used in polymer composites are fibers and strips material, bamboo fiber,carbon, PALF and malva fiber are  used as reinforcement materials and epoxy resin polymer used as matrix. The research phase began with finding the journal which explain about flexural strength in a composite that using epoxy resin as matrix. The composite manufacturing process uses the hand lay-up method. The flexural strengths data will be compare and analized. The mechanical properties tested used flexural test with ISO 14125:1998 Fibre-reinforced plastic composites – Determination of flexural properties and ASTM D790/D790M-17 “Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials”.The strongest reinforcement is carbon with 475,27 MPa, second is malva’s fiber 214,00 MPa, third is PALF 103,25 MPa, the last one is bamboo 80,30 MPa.

Joining of Composites with Metals using Graded Metal Fabric Interfaces

A major challenge in the implementation of fibre-reinforced plastics (FRPs) is the provision of stress-appropriate joints with other materials. Establishing a high-strength, graded metal fabric interface using industrially established joining methods is a target-oriented approach in this context. For this purpose, a novel solution based on a textile transition structure in combination with the evaluation of different joining methods is presented in this article. A process chain was developed that depicts both the design and production of textile transition structure as reinforcement material of the FRP component and the further processing to metal FRP composites. Within the textile transition structure, the hybrid fabrics combine glass fibre yarns and metal flat wires, where the latter enable the joining process and transfer loads into the reinforcing glass fibres. The manufacturing implementation of this new joining interface from the textile to the hybrid component is described in detail within the paper. Furthermore, results of mechanical load tests of the graded metal fabric interface are presented. The research results make a significant contribution to the development of innovative graded metal fabric interface with a benign failure behaviour and a great potential especially with regard to the efficient joining of mixed material constructions in large-scale applications.