Selection of natural fibre for hybrid laminated composites vehicle spall liners using analytical hierarchy process (AHP)

Natural fibres with variable properties are found in many engineering applications because of its low cost and biodegradability .The selection of suitable fibres involves the evaluation of a number of alternatives based on certain criteria. The purpose of this study is to suggest the use of analytical hierarchy process (AHP) in the selection of natural fibres for hybrid laminated composites. It was found that the most suitable natural fibre to be used with Kevlar 29 in hybrid laminated composites is kenaf fibre. It is expected that this finding will significantly contribute to the development of hybrid laminated composites for vehicle ballistic protection

Mechanical performance of woven kenaf-Kevlar hybrid composites

Hybrid composites offer a combination of advantages of constituent components to produce a material with determined properties. In the present work, woven hybrid composite was prepared by hand lay-up method in laminate configuration. Kevlar/kenaf hybrid composites were fabricated with total fibre content of 30% and the ratio of Kevlar/kenaf varies in weight fraction of 78/22, 60/40, 50/50, 26/74, and 32/68, respectively. The Kevlar/epoxy and kenaf/epoxy were also prepared for comparison. The mechanical properties of hybrid, kenaf/epoxy, and Kevlar/epoxy composites were tested. Morphological properties of tensile fracture surface of hybrid composites were studied by scanning electron microscopy. Results have established that the mechanical properties of kenaf-Kevlar hybrid composites are a function of fibre content. The hybrid composites with Kevlar/kenaf (78/22) ratio exhibited better mechanical properties compared to other hybrid composites. This result indicates the potential of Kevlar-kenaf hybrid composite for impact applications

Investigating ballistic impact properties of woven kenaf-aramid hybrid composites

In this study, the ballistic impact performance of woven kenaf-Kevlar hybrid and non-hybrid composites against fragment simulating projectiles (FSPs) was investigated. All the composites were prepared using the hand lay-up technique, method, followed by static load compression. The hybrid composites consist of Kevlar fabric and woven kenaf layers. The results obtained indicate that the energy absorption, ballistic limit velocity (V 50) and failure behaviour of the composites during the impact event were affected by the woven kenaf hybridisation. The additional kenaf layers in hybrid composites resulted in the increase in composites thickness and areal density, thus increased the energy absorption (14.46 % to 41.30 %) and V 50 (5.5 % to 8.44 %). It was observed that the hybrid composites failed through a combination of fibre shear, delamination and fibre fracture in the impacted surface, woven kenaf-Kevlar interface and rear surface respectively. Although the specific energy absorption was lower for the hybrid composites, further investigations need to be carried out to utilise the great potential natural fibres

Effect of post curing, fibre content and resin-hardener mixing ratio on the properties of kenaf-aramid hybrid composites

Polymer composites reinforced with high strength synthetic fibres have been used for many engineering applications. Environmental and economic issues, encourage the exploration on the introduction natural-synthetic fibre hybrid composites. Mechanical properties are critical to composite performance and may due to the manufacturing process conditions. This study investigates the effect of post curing temperature, natural fibre content and resin-hardener mixing ratio on mechanical properties of kenaf-Kevlar hybrid composites. A full factorial design (23) was carried out to determine the effect these factors on the responses: flexural strength, flexural modulus and impact strength. A statistical study has been performed in order to determine the how the factors affect the responses. The study showed that post-curing temperature, kenaf content and resin-hardener mixing ratio gives significant effects on the mechanical properties of kenaf-Kevlar hybrid composites

Effect of fibre orientations on the mechanical properties of kenaf–aramid hybrid composites for spall-liner application

This paper presents the effect of kenaf fibre orientation on the mechanical properties of kenaf–aramid hybrid composites for military vehicle's spall liner application. It was observed that the tensile strength of woven kenaf hybrid composite is almost 20.78% and 43.55% higher than that of UD and mat samples respectively. Charpy impact strength of woven kenaf composites is 19.78% and 52.07% higher than that of UD and mat kenaf hybrid composites respectively. Morphological examinations were carried out using scanning electron microscopy. The results of this study indicate that using kenaf in the form of woven structure could produce a hybrid composite material with high tensile strength and impact resistance properties

Water absorption behaviour and impact strength of kenaf-Kevlar reinforced epoxy hybrid composites

Fibre reinforced polymer composites has been used in a variety of applications. Recently, there is increasing interest in the research on natural-synthetic fibre hybrid composite. In this study, physical properties, water absorption and impact properties of woven kenaf-Kevlar hybrid composite was evaluated. In all samples, Kevlar (aramid fibres) was kept as the skin layers and kenaf as the core material. The experimental results revealed that the hybrid composites with high kenaf content show a low in density and contains a high content of the voids. Similar finding observed in water absorption and thickness swelling test as the hybrid composite with higher kenaf content absorb more water and dimensional changes. Water absorption of hybrid composite increased with the increase of kenaf content. Water absorption affects the impact strength of the composites. The result of this study is important for the further utilisation of woven kenaf in hybrid laminate composites

Review of kenaf reinforced hybrid biocomposites: potential for defence applications

Background: The present review deals with the recent development of kenaf hybrid composites. Kenaf reinforced polymer composites are made up of either thermoplastic or thermoset matrix, depending on their applications. The combination of kenaf fibre with more than two fibres in hybrid composites enhances the potential uses of kenaf in many applications. The well-known limitations of natural fibres, such as lack of thermal stability, strength degradation, water absorption and poor impact properties, encourage the exploration of hybridisation with high performance fibres. Methods: We review the researches on kenaf reinforced composites and kenaf reinforced hybrid biocomposites. This review covers the types of matrix used, methods applied in manufacturing the hybrid composites and the potential application of the hybrid composites. Results: Kenaf fibres are widely used in fibre reinforced composites. There are limitations in the use of kenaf in polymeric composites, including high moisture absorption, non-uniformity and poor mechanical properties. Hybridisation of kenaf fibre with other fibres resulted in the hybrid composites with comparable strength, stiffness, strength to weight ratio, resistance and other physical and mechanical properties. The selection of matrix materials also plays an important role in fibre reinforced composites materials. There will be an increase in the use of natural fibre hybrid composites in areas such as household products and automotives. Conclusion: Kenaf fibres play an important role in multi-application composites. This fibre is used solely in polymer matrix or in combination either with other natural fibres or with synthetic fibres. Kenaf hybrid composites are being developed as a potential alternative to reduce the use of synthetic fibres such as aramid or glass fibres

Quasi-static penetration and ballistic properties of kenaf-aramid hybrid composites

In this research, quasi-static penetration and ballistic properties of non-woven kenaf fibres/Kevlar epoxy hybrid laminates with thicknesses ranging from 3.1 mm to 10.8 mm by hard projectile at normal incidence have been experimentally investigated. Hybrid composites were fabricated by hand lay-up technique in a mould and cured at room temperature for 24 h by static load. Hybrid composites consist of Kevlar layers and non-woven kenaf layers at three different configurations, i.e. kenaf at the innermost layers, outermost layers and at the alternating layers. Kevlar/epoxy and kenaf/epoxy composites were also fabricated for comparison purpose. Quasi-static experiments were conducted using a tensile testing machine at the speed of 1.27 mm/min and 2.54 mm/min. Ballistic tests were conducted using 9 mm full metal jacket bullet using a powder gun at speeds varying from 172 to 339 m/s, with the initial and a residual velocity of the projectiles is measured. The tested sample was carefully examined with respect to failure modes. Results showed the effect of hybridization in term of force–displacement curves, energy dissipation and damage mechanisms for quasi-static test. Maximum force to initiate penetration is higher in hybrid composites compared to kenaf/epoxy and Kevlar/epoxy composites. Hybridization of kenaf–Kevlar resulted in a positive effect in terms of energy absorbed (penetration) and maximum load. In the case of ballistic tests, hybrid composites recorded lower ballistic limit (V50) and energy absorption than the Kevlar/epoxy composite. The V50 of hybrid composites with kenaf at the outermost layers is superior to other hybrid composites. These finding inspired further exploration of hybrid composite for ballistic armour spall-liner application

Mechanical and morphological properties of bio-phenolic/epoxy polymer blends

Polymer blends is a well-established and suitable method to produced new polymeric materials as compared to synthesis of a new polymer. The combination of two different types of polymers will produce a new and unique material, which has the attribute of both polymers. The aim of this work is to analyze mechanical and morphological properties of bio-phenolic/epoxy polymer blends to find the best formulation for future study. Bio-phenolic/epoxy polymer blends were fabricated using the hand lay-up method at different loading of bio-phenolic (5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%) in the epoxy matrix whereas neat bio-phenolic and epoxy samples were also fabricated for comparison. Results indicated that mechanical properties were improved for bio-phenolic/epoxy polymer blends compared to neat epoxy and phenolic. In addition, there is no sign of phase separation in polymer blends. The highest tensile, flexural, and impact strength was shown by P-20(biophenolic-20 wt% and Epoxy-80 wt%) whereas P-25 (biophenolic-25 wt% and Epoxy-75 wt%) has the highest tensile and flexural modulus. Based on the finding, it is concluded that P-20 shows better overall mechanical properties among the polymer blends. Based on this finding, the bio-phenolic/epoxy blend with 20 wt% will be used for further study on flax-reinforced bio-phenolic/epoxy polymer blends

Thermal degradation and viscoelastic properties of Kevlar/Cocos nucifera sheath reinforced epoxy hybrid composites

The aim of this research work is to develop high performance structural composites using Kevlar 29 (K) and Cocos nucifera sheath (CNS). The Kevlar and CNS laminates were fabricated by using hand lay-up method followed by hot pressing. The weight ratios of Kevlar/CNS are as follows 100/0 (S1), 75/25(S2), 50/50 (S3), 25/75 (S4), 0/100(S5). Thermal and viscoelastic properties of laminated composites were investigated as a function of temperature using thermogravimetric (TGA) and dynamic mechanical analyzer (DMA). The obtained results revealed that the thermal stability, char residue of S2 laminate was higher compared S3, S4 and S5 laminates. Moreover, S2 laminates showed comparable thermal stability with Kevlar/epoxy composites (S1). Differential scanning calorimetry (DSC) results revealed that hybrid composite (S2) offers a virtuous resistance or stability towards heat in the epoxy composites. Viscoelastic analysis results showed that the storage modulus (E’) and loss modulus (E”) of S2 composites were higher among the laminates due to improved interfacial interactions and effective stress transfer rate. Moreover, the damping of hybrid laminates (S2) almost closer to Kevlar/epoxy laminates (S1). Hence, it was observed that hybrid Kevlar/CNS composites (S2) can be efficiently utilized for advanced structural applications where rigidity, thermal stability along with renewability are prime requirements