Fabrication and preliminary assessment of aramid reinforced polymer composite material

A knowledge of the material constituents and fabrication process is generally required for easing the composite material properties study and characterization. This paper presents the methodology of aramid reinforced polymer composite material preliminary assessment and fabrication. The demonstration is carried out through the development of mechanical properties characterization specimen. The composite material specimen is fabricated by utilizing the open mould with hand lay-up method, where three types of laminates include of unidirectional, orthotropic, quasi-isotropic cross plies are demonstrated. A template is applied for preparing specific fibre orientation 45°angle. Plies are lay accordingly with guided by a square guide for minimizing the off-orientation angle defect. Preliminary assessment is included of verification of unidirectional aramid fabric quality, cured specimen physical defect, internal defect through micrography analysis and material volume fraction prediction. Average specimen fibre volume fraction of 0.64 is predicted by determined the fibre filament geometry detail through micrography analysis. There are several fabrication defects had been identified. The defect identification findings shall be referred for further improvement of material preparation and fabrication method.

Effects of compressing parameters and Mg(OH)2 content on mechanical properties and flame retardancy of rice straw-fibre reinforced composites

Rice straw fibre was utilized for unidirectional (UD) composites. In this study, the effects of compression temperature, duration, pressure, and fibre volume fraction on the mechanical properties of composites were investigated, respectively. The composite with optimal mechanical properties was prepared at a temperature of 180oC, pressure of 125 kg.cm-2 for 10 min, and at a fibre volume fraction of 40%. Mg(OH)2 was found to be an appropriate additive to enhance the flame retardancy of the composite. Interestingly, this agent also improved the mechanical and thermal insulation properties of the obtained composite.

Determination of Single Parameter for Serviceability Requirements of Fibre Reinforced Concrete: Study of Fracture Characteristics

This The influence of fibre reinforcement on crack propagation in concrete was studied . Thirty-five double torsion specimens, made with three types of fibres (fibre glass , straight steel fibres and deformed steel fibres ) were tested . The variables were the fibre volume and size of the fibres. The test results indicated that the resistance to rapid crack growth increased somewhat with increasing fibre content up to about 1.25% - 1.5% by volume. The degree of compaction had an enormous effect on the fracture properties .The fracture toughness increased with fibre content up to about 1.25% by volume, and then decreased , due to incomplete compaction. It was found that in this test geometry, fibres did not significantly restrain crack growth. It was also observed that once the crack had propagated down the full length of the specimen, the system changed from a continuous system to a discontinuous system, consisting of two separate plates held together by the fibre reinforcement. Different types of fibres did not significantly affect the fracture toughness. Keywords: Fibre glass, straight steel fibers, deformed steel fibers, fracture toughness.

Assessment of Water Permeability Test on Polypropylene based Self-Compacted Fibre Reinforced Concrete (PSCFRC)

An investigation conducted to study the effect of water permeability and strength characteristics such as compressive strength of Polypropylene self-compacted fibre reinforced concrete (PSCFRC) is presented. Polypropylene fibres of lengths, 35 mm with a diameter of 0.44 mm, were systematically combined in different mix proportions to combinations of 0.2%, 0.4%, and 0.6% Polypropylene fibre volume fraction. For comparison, a concrete mix with no fibres was also mixed. A total of 72 cube specimens of 150 mm were tested, 36 each for compressive strength and water permeability at 28 and 56 days of curing. According to the findings of this study, a fibre combination of SCFRC 0.6 percent is the most acceptable fibre composition to use in Polypropylene self-compacted fibre reinforced concrete (PSCFRC) for maximum performance in terms of compressive strength and water permeability requirements together.

Strength and flexural toughness of hybrid fibre reinforced fly ash based concrete

To overcome concrete brittleness and to provide toughness, fibre reinforcement is commonly utilized. Fibre reinforcement to concrete in the form of hybrid fibre is a new concept to achieve individual fibre benefits. In this paper, the effect of polypropylene fibre (PF) and steel fibre (SF) either individually or with different combinations at 1% fibre volume fraction on the strength, flexural toughness, and Ultrasonic pulse velocity (UPV) value of FIBRE-reinforced fly ash (FA) based concrete has been presented. For this purpose, one control mix having 25% FA and 0% fibre and five mixes with different hybrid fibre combinations of 1%PF-0%SF, 0.75%PF-0.25%SF%, 0.50%PF-0.50%SF, 0.25%PF-0.75%SF, and 0%PF-1%SF were cast. ASTM C 1609 method was utilized to evaluate the flexural toughness. Experimental results have shown an improvement in all the above-said properties (expect UPV) by the addition of fibre, but improvement is more significant in mixes with a higher percentage of SF when compared with mixes at a higher percentage of PF. Mix with a hybrid fibre combination of 0.25% PF and 0.75% SF gave the best result among all the fibre-reinforced fly ash-based mixes.

3D printed continuous glass fibre-reinforced polyamide composites: Fabrication and mechanical characterisation

Fused Filament Fabrication is a very common additive manufacturing technology and several manufacturers have developed commercial 3D-printers that enable the use of fibre-reinforced filaments in order to improve the mechanical properties of the printed parts. The obtained material is a composite that exhibits complex mechanical properties. The aim of this study is to characterize the mechanical behaviour of 3D-printed continuous glass fibre-reinforced polyamide composites. In a first step, we focus on the reinforced filament: the heterogeneity of its microstructure is evidenced as well as its brittle elastic tensile behaviour. In a second step, parts of different fibre orientations and fibre volume contents are manufactured using a Mark Two 3D-printer (MarkForged®), their microstructure is analysed and tensile, flexural and short beam bending tests are performed. As expected, the results show a significant influence of fibre volume content and fibre orientation. Standard homogenization methods are used to compare the predicted mechanical behaviour to the experimental results. Regarding the elastic stiffness, a good correlation is observed when the material is loaded in the direction of the fibres. Regarding the tensile strength, the results show that no benefit is obtained above a fibre volume content of about 11%. These results highlight the importance of choosing an optimised stacking sequence prior to the printing process, in order to obtain composites with the desired mechanical properties. The mechanical results are analysed in the light of Scanning Electron Microscopy observations of specimen cross-sections before and after testing.

Review on Manufacture of Military Composite Helmet

Despite of the fact that more and more accessory devices are integrated to functionalize a ballistic helmet system, its core ballistic protective function needs to be improved with weight reduction was and still is the main course in engineering design. The two major generic classes of synthetic fibres for ballistic composites are Ultra High Molecular Weight Polyethylene (UHMWPE) fibre (0.97 g/cm3) and aramid fibre (1.44 g/cm3). In the area of military helmets, these fibres are constructed into different topologies, draping/forming into double-curvature geometric shape in multiple plies, serving as reinforcement for composite shell. The preforming ways influence the subsequent impregnation / solidification and curing step in manufacture, in terms of the fibre orientation and fibre volume fraction. The inherent structural heterogeneity thus leads to scatter in permeability and composite thickness, and have further impact in generating process-induced defects. During the processing, the fibre continuity without wrinkles, together with voids-free are determinative factors to a quality final part. The aim of this paper is to review the manufacturing technologies characterised by thermo-mechanical forming and Liquid Composite Moulding (LCM), relating their processing parameters respectively to the properties of reinforcements in one dimension (1D), two dimensions (2D) and three dimensions (3D), along with that of the matrix in dry or wet phase, interdependency of them are sought.

Method for the Microstructural Characterisation of Unidirectional Composite Tapes

The outstanding properties of carbon fibre-reinforced polymer composites are affected by the development of its microstructure during processing. This work presents a novel approach to identify microstructural features both along the tape thickness and through the thickness. Voronoi tessellation-based evaluation of the fibre volume content on cross-sectional micrographs, with consideration of the matrix boundary, is performed. The method is shown to be robust and is suitable to be automated. It has the potential to discriminate specific microstructural features and to relate them to processing behaviour removing the need for manufacturing trials.