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The purpose of this paper is to investigate the effect of thermal‐oxidative aging at 150°C on the mechanical properties of carbon fibre reinforced bismaleimide composites.

Composites specimens after thermo‐oxidative aging at 150°C for various times (up to 1,000 h) were investigated by scanning electron microscopy (SEM) for fracture morphology, Fourier transform infrared (FTIR) spectroscopy for chemical structures, and flexural strength test and inter‐laminar shear strength (ILSS) test for mechanical properties.

The results indicated that the mechanical properties of carbon fibre/BMI composites were affected significantly by testing temperature rather than by aging time. SEM results showed that the good adhesion of fibre and matrix resulted in the better mechanical properties. The composites showed lower flexural strength and ILSS at 150°C due to the viscoelastic behaviour of matrix resin. The FTIR spectra confirmed the decomposition of crosslinked maleimide occurred just on the surface of composites during various aging times.

Results indicated that carbon fibre/BMI composites had excellent heat resistance and aging resistance.

Due to their excellent thermal and mechanical properties, the carbon fibre/BMI composites show greater potential for their applications in some extreme fields such as aerospace and machine.

The paper investigates the relationships of the fracture morphologies of composites and chemical structures of matrix resin to the mechanical properties after thermo‐oxidative aging.

In the recent years, the industries show interest in natural and synthetic fibre-reinforced hybrid composites due to weight reduction and environmental reasons. The purpose of this experimental study is to investigate the properties of the hybrid composites fabricated by using carbon, untreated and alkaline-treated hemp fibres.

The composites were tested for strengths under tensile, flexural, impact and shear loadings, and the water absorption characteristics were also observed. The finite element analysis (FEA) was carried out to analyse the elastic behaviour of the composites and predict the strength by using ANSYS 15.0.

From the experimental results, it is observed that the hybrid composites can withstand the maximum tensile strength of 61.4 MPa, flexural strength of 122.4 MPa, impact strength of 4.2 J/mm² and shear strength of 25.5 MPa. From the FEA results, it is found that the maximum stress during tensile, flexural and impact loading is 47.5, 2.1 and 1.03 MPa, respectively.

The results of the untreated and alkaline-treated hemp-carbon fibre composites were compared and found that the alkaline-treated composites perform better in terms of mechanical properties. Then, the ANSYS-predicted values were compared with the experimental results, and it was found that there is a high correlation occurs between the untreated and alkali-treated hemp-carbon fibre composites. The internal structure of the broken surfaces of the composite samples was analysed using a scanning electron microscopy (SEM) analysis.

The main idea is the comparison between composites including natural fibres (such as the linoleum fibres) and typical composites including carbon fibres or glass fibres. The comparison is proposed for different structures (plates, cylinders, cylindrical and spherical shells), lamination sequences (cross-ply laminates and sandwiches with composite skins) and thickness ratios. The purpose of this paper is to understand if linoleum fibres could be useful for some specific aerospace applications.

A general exact three-dimensional shell model is used for the static analysis of the proposed structures to obtain displacements and stresses through the thickness. The shell model is based on a layer-wise approach and the differential equations of equilibrium are solved by means of the exponential matrix method.

In qualitative terms, composites including linoleum fibres have a mechanical behaviour similar to composites including glass or carbon fibres. In terms of stress and displacement values, composites including linoleum fibres can be used in aerospace applications with limited loads. They are comparable with composites including glass fibres. In general, they are not competitive with respect to composites including carbon fibres. Such conclusions have been verified for different structure geometries, lamination sequences and thickness ratios.

The proposed general exact 3D shell model allows the analysis of different geometries (plates and shells), materials and laminations in a unified manner using the differential equilibrium equations written in general orthogonal curvilinear coordinates. These equations written for spherical shells degenerate in those for cylinders, cylindrical shell panels and plates by means of opportune considerations about the radii of curvature. The proposed shell model allows an exhaustive comparison between different laminated and sandwich composite structures considering the typical zigzag form of displacements and the correct imposition of compatibility conditions for displacements and equilibrium conditions for transverse stresses.

Composites 3D printing has the potential to replace the conventional manufacturing processes for engineering applications because it allows for the manufacturing of complex shapes with the possibility of reducing the manufacturing cost. This paper aims to analyse the performance of 3D printed fibre reinforced polymer composites to investigate the energy absorption capabilities and the residual properties before and after impact.

Various composites composed of carbon fibres and Kevlar fibres embedded into both Onyx and nylon matrix were printed using Markforged-Two 3D printers. Specimens with different fibre orientations and fibre volume fractions (Vf) were printed. A drop-weight impact test was performed at energies of 2, 5, 8 and 10 J. Flexural testing was performed to evaluate the flexural strength, flexural modulus and absorbed energy under bending (AEUB) before and after impact. Additionally, 3D printed carbon fibre composites were tested at two different temperatures to study their behaviour under room and sub-ambient temperatures. Failure modes were investigated using optical and high depth of field microscopes for all 3D printed composite samples.

Kevlar/nylon composites with a unidirectional lay-up and 50% Vf exhibited the most prominent results for AEUB at room temperature. The high-Vf carbon fibre composite showed the highest ultimate strength and modulus and performed best at both temperature regimes.

The work, findings and testing produced in this paper are entirely original with the objective to provide further understanding of 3D printed composites and its potential for use in many applications.

Fused filament fabrication (FFF) is one of the most popular additive manufacturing (AM) technologies due to its ability to build thermoplastic parts with complex geometries at low cost. The FFF technique has been mainly used for rapid prototyping owing to the poor mechanical and geometrical properties of pure thermoplastic parts. However, both the development of new fibre-reinforced filaments with improved mechanical properties, and more accurate composite 3D printers have broadened the scope of FFF applications to functional components. FFF is a complex process with a large number of parameters influencing product quality and mechanical properties, and the effects of the combined parameters are usually difficult to evaluate. An array of parameter combinations has been analysed for improving the mechanical performance of thermoplastic parts such as layer thickness, build orientation, raster angle, raster width, air gap, infill density and pattern, fibre volume fraction, fibre layer location, fibre orientation and feed rate. This study aims to assess the effects of nozzle diameter on the mechanical performance and the geometric properties of 3D printed short carbon fibre-reinforced composites processed by the FFF technique.

Tensile and three-point bending tests were performed to characterise the mechanical response of the 3D printed composite samples. The dimensional accuracy, the flatness error and surface roughness of the printed specimens were also evaluated. Moreover, manufacturing costs, which are related to printing time, were evaluated. Finally, scanning electron microscopy images of the printed samples were analysed to estimate the porosity as a function of the nozzle diameter and to justify the effect of nozzle diameter on dimensional accuracy and surface roughness.

The effect of nozzle diameter on the mechanical and geometric quality of 3D printed composite samples was significant. In addition, large nozzle diameters tended to increase mechanical performance and enhance surface roughness, with a reduction in manufacturing costs. In contrast, 3D printed composite samples with small nozzle diameter exhibited higher geometric accuracy. However, the effect of nozzle diameter on the flatness error and surface roughness was of slight significance. Finally, some print guidelines are included.

The effect of nozzle diameter, which is directly related to product quality and manufacturing costs, has not been extensively studied. The presented study provides more information regarding the dependence of the mechanical, microstructural and geometric properties of short carbon fibre-reinforced nylon composite components on nozzle diameter.

The purpose of this study is to bring out the machining characteristics of abrasive jet machining on carbon fibre reinforced thermoplastic composites utilized in aerospace and biomedical applications. Biocompatibility materials such as carbon fibres and polyether thermoplastics, like polyether ether ketone (PEEK) are widely used in trauma and orthopaedic surgery. Due to the heterogeneity, layered construction of reinforcing phase bonds with a resin matrix and abrasiveness of the reinforcing fibre, traditional drilling of carbon fibre-reinforced composites (CFRPs) are always challenging task.

An investigation is carried out using abrasive jet machine for drilling PEEK filled with 30 Wt.% carbon fibre (CF 30) using threaded and unthreaded nozzle to study the effect of abrasive jet process variables on surface roughness (R_a) and delamination factor (D_F). Pressure (P) and stand-off distance (SOD) as important technological abrasive jet factors were evaluated. It is found that higher abrasive jet pressure and minimum SOD maybe selected to achieve minimum delamination.

The study further reported that the threaded nozzle minimized the surface roughness by 43% and delamination factor up to 12%.

This study of experimenting and observing the machining characteristics of CF30 by using a threaded nozzle is being tried for the first time and the results are deliberated.

In industry, fused filament fabrication (FFF) offers flexibility and agility by promoting a reduction in costs and in the lead-time (i.e. time-to-market). Nevertheless, FFF parts exhibit some limitations such as lack of accuracy and/or lower mechanical performance. As a result, some alternatives have been developed to overcome some of these restrictions, namely, the formulation of high performance polymers, the creation of fibre-reinforced materials by FFF process and/or the design of new FFF-based technologies for printing composite materials. This work aims to analyze these technologies.

This work aims to study and understand the advances in the behaviour of 3D printed parts with enhanced performance by its reinforcement with several shapes and types of fibres from nanoparticles to continuous fibre roving. Thus, a comprehensive survey of significant research studies carried out regarding FFF of fibre-reinforced thermoplastics is provided, giving emphasis to the most relevant and innovative developments or adaptations undergone at hardware level and/or on the production process of the feedstock.

It is shown that the different types of reinforcement present different challenges for the printing process with different outcomes in the part performance.

This review is focused on joining the most important researches dedicated to the process of FFF-printed parts with different types reinforcing materials. By dividing the reinforcements in categories by shape/geometry and method of processing, it is possible to better quantify performance improvements.

3D printing of composites has a high degree of design freedom, which allows for the manufacture of complex shapes that cannot be achieved with conventional manufacturing processes. This paper aims to assess the design variables that might affect the mechanical properties of 3D-printed fibre-reinforced composites.

Markforged Mark-Two printers were used to manufacture samples using nylon 6 and carbon fibres. The effect of fibre volume fraction, fibre layer location and fibre orientation has been studied using three-point flexural testing.

The flexural strength and stiffness of the 3D-printed composites increased with increasing the fibre volume fraction. The flexural properties were altered by the position of the fibre layers. The highest strength and stiffness were observed with the reinforcement evenly distributed about the neutral axis of the sample. Moreover, unidirectional fibres provided the best flexural performance compared to the other orientations. 3D printed composites also showed various failure modes under bending loads.

Despite multiple studies available on 3D-printed composites, there does not seem to be a clear understanding and consensus on how the location of the fibre layers can affect the mechanical properties and printing versatility. Therefore, this study covered this design parameter and evaluated different locations in terms of mechanical properties and printing characteristics. This is to draw final conclusions on how 3D printing may be used to manufacture cost-effective, high-quality parts with excellent mechanical performance.

A review of CFRP dealing with its processing, properties and some of the ways in which it could be used in conjunction with conventional materials. The importance of the utilization of carbon fibres in commercially useful as well as experimental structures is discussed. This may be achieved by using the fibres in conjunction with conventional sheet metal components, as a preliminary step toward the 100 per cent reinforced plastic structure. A few such applications are described, together with a brief summary of the fibre processing and properties as an aid to preliminary design studies.

The purpose of this paper is to investigate the deposition of uniform, adherent and crack‐free Ni‐P thin films on carbon fibres using the electroless deposition technique.

Before applying the electroless process, the carbon fibre surfaces must be subjected to several treatment processes to remove the organic binder, etching and surface metallization. The surface morphology of the Ni‐P coatings was assessed using a scanning electron microscope (SEM). The chemical compositions of Ni‐P layers were identified by energy dispersive X‐ray analysis (EDS). The bond strength of the coated layer was determined by measuring the electrical resistance at the fibre/coating interface. The magnetic properties of the fibres were estimated using a hysteresis diagram. The tensile performance of single fibres coated by Ni‐P has been investigated with respect to coating thickness.

Pre‐treatment processes are used to improve the adhesion of Ni‐P layers and to obtain homogeneous coatings. The influence of plating parameters (temperature, pH and time) on the coating thickness of the Ni‐P layer was investigated. It was found that the coating thickness increased as the pH value, plating time and the temperature of the bath increased. The results revealed that a complete and uniform Ni‐P coating on fibre could be obtained at optimum conditions 85°C, pH 6, for 60 min, and the results indicated that the P content in the electroless deposit is approximately 3.4 wt%. The tensile strength values are improved significantly after coating and increased by 3‐5 times with increasing of coating thickness from 0.3 to 2 μm.

The results presented in this work are an insight into understanding of the deposition and adherence of Ni‐P thin films on carbon fibre using the electroless technique and behaviour of the coated fibre.