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.

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.

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.

Wear behaviour of polymeric materials reinforced with man-made fibres: A comprehensive review about fibre volume fraction influence on wear performance

In the mineral processing, mining, oil and gas industries, it is not uncommon to find mechanical components exposed to degradation and wear from slurries. Polymeric matrix composites (PMCs) are considered as potential alternatives to replace metallic materials in such severe environments because of their high strength to weight ratio, ease of production, high wear resistance and good corrosion/chemical resistance. Often, seemingly erratic wear behaviour is observed making preventive maintenance and time-to-failure difficult to manage. A major culprit is the complex physical and chemical interaction with the slurry, such as exposure to high temperatures, high alkalinity, high slurry density, insoluble inorganic contents, high hardness of suspended particles and humidity. It is well understood that the addition of reinforcing fibres greatly improves the stiffness and strength of polymeric matrix composites. However, the effect the reinforcement has on the wear performance is far less established and a framework to analyse the effect of fibre volume fraction is yet to be established. The difficulties in establishing such a framework lay in the multi-factorial contributions and the potential trade-offs with mechanical performance. This makes it much more difficult to isolate clear trends. The objective of the present work is to present a comprehensive review on the influence reinforcing fibres play on wear behaviour of PMCs. The influence of fibre volume fraction on wear performance of polymeric composites reinforced with man-made fibres is presented. The applied load, fibre length, coefficient of friction and chemical treatment of fibres are analysed with respect to wear performance of PMCs. Future trends in the use of fibre-reinforced polymeric composites in wear critical applications are identified. Research gaps in designing composites for wear applications are explained, aiming at motivating future research to address these gaps.

Thermoplastic RTM: Impact Properties of Anionically Polymerised Polyamide 6 Composites for Structural Automotive Parts

This study investigates the impact behaviour and post-impact performance of polyamide-6 glass fibre reinforced composites, manufactured by thermoplastic resin transfer moulding. Impact test samples were extracted from quasi-isotropic laminates using two different glass fibre sizings, both with a fibre volume fraction of approximately 52%. A previous study showed that one of these sizings enhanced the interfacial strength and Mode I fracture toughness; however, the effects of the sizing on out-of-plane impact is of greater significance in terms of automotive applications. A drop-weight impact tester was used to determine out-of-plane impact performance for both sizings in terms of impact load-induced and energy returned from the striker. High-speed video of the impact response was simultaneously captured. Testing was carried out at three impact energy levels: two sub-penetration and one full penetration. The impact damage area was observed, and the post-damage compression properties of samples were measured to determine the reduction in their strength and stiffness. Results showed that the use of different sizing technologies had little effect on the post-impact compressive properties and that penetration led to only a 29% drop in compression strength. Overall, the outcomes of this work demonstrate the potential of these materials in automotive applications.

Fibre bridging and nozzle clogging in 3D printing of discontinuous carbon fibre-reinforced polymer composites: coupled CFD-DEM modelling

A coupled multiphase model based on computational fluid dynamics (CFD) and discrete element method (DEM) is developed to numerically investigate the extrusion-based 3D printing process of discontinuous carbon fibre-reinforced polymer composites. Short carbon fibres are modelled as rigid bodies by clumping discrete spheres in DEM, while polymer matrix is treated as an incompressible Newtonian fluid in CFD. A fluid-particle interaction model is adopted to couple DEM and CFD and represent the dynamic fibre/matrix interaction. Collisions between fibres are considered naturally in DEM by using the Hertz-Mindlin contact law. The coupled CFD-DEM is validated, both qualitatively and quantitatively, against X-ray microtomography (μCT) experimental results for the T300/PA6 composite. Parametric study on various fibre lengths, fibre volume fraction and resin viscosity using the CFD-DEM model shows that the nozzle clogging tends to occur when the fibre length and/or the fibre volume fraction are increased. Use of a polymer matrix with a lower viscosity can be effective to eliminate the clogging issue when printing composites with relatively short fibres. The fibre length is dominating when long fibres are used and the clogging is largely independent on the viscosity of the polymer matrix. Finally, a potential solution of using a cone sleeve insert located above the shrinking region to address the nozzle clogging issue is proposed and numerically assessed.

Investigation of Thermal, Mechanical and Transport Properties of Ultra-Lightweight Foamed Concrete (ULFC) Strengthened with Alkali Treated Banana Fibre

Traditionally, Ultralightweight Foam Concrete (ULFC) is primarily used to replace filling excavations, ditch restoration and underground channels, because of their high porosity, water absorption and low strength. Yet, ULFC is characterized by excellent thermal properties and could be an alternative for sustainable energy-efficient building material. This study investigates the properties of an ULFC strengthened with alkali-treated banana fibre. The low density ULFC of 600kg/m3 was fabricated and strengthened with alkali-treated banana fibre. Fibre volume fraction of 0.25%, 0.35%, 0.45% and 0.55% were compared to the unreinforced specimens, serving as the control specimen (no fibre addition). Mix proportioning of 1:1.5:0.45 of cement, sand, and water was respectively adopted throughout the mix. The alkali treated banana fibre strengthened ULFC was tested for compressive strength, sorptivity and thermal properties. Morphology of the treated fibre and ULFC composites was studied using SEM micrograph. The result depicts that ULFC exhibited the optimum compressive strength of 1.1604N/mm2 with the fibre volume fraction of 0.35%. Sorptivity or rate of water absorption was testified to upsurge, after 24 hours duration at fibre volume fraction of 0.55%, recording a 56.12% increment compared to the control specimen. The finding displays that at the highest-fibre volume fraction of 0.55%, thermal conductivity and diffusivity decrease by 13.17% and 28.16%, correspondingly, whiles the specific heat capacity increases to 37.17% all compared with unreinforced specimens. SEM images reveal that the presence of lumen and the nature of porous and fibrous alkali-treated banana fibre. Hence, it is endorsed that ULFC produced with alkali-treated banana fibre should be utilized as an infill material for composite system.