Mechanical properties of fibre-metal laminates made of natural/synthetic fibre composites

Mechanical properties are among the properties to be considered in designing and fabricating any composite to be used as a firewall blanket in the designated fire zone of an aircraft engine. The main focus of this work was to study the tensile, compression, and flexural strengths of the combination of natural/synthetic fibres with metal laminates as reinforcement in a polymer matrix. The materials included flax fibres, kenaf fibres, carbon fibres, aluminium alloy 2024, and epoxy. The two-hybrid fibre metal laminate composites were made from different layers of natural/synthetic fibres with aluminium alloy of the same thickness. The composites were made from carbon and flax fibre-reinforced aluminium alloy (CAFRALL) and carbon and kenaf fibre-reinforced aluminium alloy (CAKRALL). Based on the results obtained from the mechanical tests, the CAFRALL produced better mechanical properties, where it had the highest modulus of elasticity of 4.4 GPa. Furthermore, the CAFRALL was 14.8% and 20.4% greater than the CAKRALL in terms of the tensile and compressive strengths, respectively, and it had a 33.7% lower flexural strength. The results obtained in the study shows that both composites met the minimum characteristics required for use in the fire-designated zone of an aircraft engine due to their suitable mechanical properties

Thermomechanical and dynamic mechanical properties of bamboo/woven kenaf mat reinforced epoxy hybrid composites

The dimensional stability and dynamic mechanical properties on bamboo (non woven mat)/kenaf (woven mat) hybrid composites was carried out in this study. The hybridization effect of bamboo (B) and kenaf (K) fibers at different weight ratio were studied at B:K:70:30, and B:K:30:70 while maintaining total fiber loading of 40% by weight. The coefficient of thermal expansion (CTE) and dynamic mechanical properties of composites were analyzed by thermomechanical anlayzer (TMA), and dynamic mechanical analyzer (DMA), respectively. Positive hybridization effects were observed on B:K:50:50 hybrid composite with lowest CTE and highest dynamic mechanical properties among all composites. The dimensional stability were strongly influence by the fiber orientation where all composites shows prominent expansion in the transverse fibers direction but relatively low expansion in longitudinal fibers direction. Dynamic mechanical properties in term of complex modulus (E*), storage modulus (E′), loss modulus (E″), Tan delta and Cole-Cole plot were studied. DMA results reveal that B:K:50:50 hybrid composite possess the highest complex modulus due to the strong fiber/matrix interfacial bonding which supported by the coefficient of effectiveness and Cole-Cole plot. Hence, it is concluded that 50:50 weight ratio of bamboo and kenaf fibers is the optimum mixing ratio to enhance both dimensional and dynamic mechanical properties of hybrid composites, and it can be utilized for automotive or building materials applications which demand high dimensional stability and dynamic mechanical properties

Fire behavioural and mechanical properties of carbon fibre reinforced aluminium laminate composites for aero-engine

Two different properties of fibre-metal laminate composites (FML), including the fire behaviour and mechanical properties, were experimentally studied in this paper. The fibre-metal laminate composites studied were made of aluminium alloy 2024-T3, carbon fibre, flax, kenaf and epoxy resin/hardener arranged in different forms. The aims of the study are to assess the fire behaviour of the composites using ISO2685 standard and mechanical properties of the composite after withstanding the burn-through according to the standard. The fire test was carried out using ISO2685 standard using a propane-air burner, whereby the propane gas and air serves as the fluid to the system. The universal testing machine of the 100 kN load cell and gun tunnel were used for the mechanical properties test according to each test standard. The fire results showed that three of the FML composites considered in the study are fireproof composites while carbon fibre kenaf reinforced aluminium laminate (CARALL4) is a fire resistant composite. Carbon fibre reinforced aluminium laminate with aluminium alloy at the front and the rear face (CARALL2) withstood higher flame temperature than the other FML composites with 14.4%, 49.0% and 82.8% greater than CARALL1, CARALL3 and CARALL4 in terms of thermal conductivity. In terms of mechanical properties, it was also CARALL2 that has higher tensile, compressive, flexural and impact strength. Therefore, the study showed that carbon fibre flax reinforced aluminium laminate (CARALL3) which is the hybrid composite with green fibre can compete with fibre-metal laminate composites of pure synthetic fibre in terms of their properties

Effect of corrugated wall combined with backward-facing step channel on fluid flow and heat transfer

The turbulent fluid flow and heat transfer were numerically studied through backward-facing step combined with various corrugated walls. The governing equation was solved using Finite Volume Method (FVM) and the SIMPLE algorithm was applied to investigate the effect of backward-facing step with corrugated downstream on heat transfer characteristics. A constant heat flux was applied on the downstream wall, while the other walls were considered as adiabatic surfaces. Parameters such as corrugated design, amplitude height (1, 2, 3, 4 and 5 mm) and Reynolds number (Re) in the range of 5000 to 20,000 were used. The performance evaluation criteria (PEC) were estimated to show the heat transfer augmentation. The results indicated that using a corrugated wall with a backward-facing step increased significantly the heat transfer accompanied by a slight increase in the skin friction coefficient simultaneously. The best heat transfer augmentation was observed for the trapezoidal corrugation at 4 mm amplitude height and 20 mm pitch diameter. Combining the corrugated wall with backward-facing step enhanced the Nusselt number (Nu) up to 62% at Re = 5000. The performance evaluation criteria increased with the increase of amplitude height until it reached 4 mm and then decreased steeply

Thermal properties of HL002-TA/B epoxy resin/hardener in fibre metal laminates composites for aero-engine

Fibre metal laminates (FML) composite are now widely used in many industries such as aerospace and automobile industries among others due to their superior properties compared to those of traditional materials; therefore the thermal stability and viscoelastic properties of the composite play important roles in high temperature application. The main purpose of this study is to evaluate the performance of the composites at high temperature application in fire designated zone of an aircraft engine. The composites were fabricated in a mold using hand lay-up method, compressed using a compression machine and then cured for 24 hours. The composites were heated from ambient temperature to a certain higher temperature at different heating rates using nitrogen and air gas for mass loss during thermogravimetric analysis (TGA), storage modulus, loss modulus and tan delta for dynamics mechanical analysis (DMA). The TGA result indicated a remarkable improvement in the thermal stability of all the fibre metal laminate composites where carbon fibre reinforced aluminium laminate with aluminium alloy at front and rear face had the highest percentage of residue which was 58.85%, while the smallest percentage was shown by the composite that was hybridized with natural fibre (kenaf). Dynamic mechanical results showed an increase in the storage modulus and an average glass transition temperature in the presence of polymer used; higher increment was observed on carbon fibre reinforced aluminium alloy with aluminium alloy at front and rear face. This investigation confirmed that fibre metal laminates of aluminium alloy 2024-T3, carbon fibre, epoxy and some other types of natural fibres composites possess excellent features that can be used in fire designated zone of an aircraft engine nacelle in the near future

Experimental study of nanofluids flow and heat transfer over a backward-facing step channel

The forced convective heat transfer and friction factor of nanofluidsflow over a backward-facing step (BFS) in achannel with the base wall dissipating a uniform heatflux are experimentally investigated in this paper. Nano-particles such as CuO and MgO dispersed in pure ethylene glycol (EG) with average diameters of 40 nm, and vol-ume concentrations of 0, 1, 3, and 5% are considered as the working nanofluids. The results indicate that the heattransfer rate increases as the volume concentration of nanoparticles increased. The Nusselt number is enhancedup to 11% at 0.05 volume concentration compared to pure EG. The friction factor increases up to approximately 15% at Reynolds number (Re) of 5000 and volume concentrations of 0.01 and 0.03. The maximum value ofthe PEC in a BFS channel is 1.5 for the CuO-EG and 1.2 for the MgO-EG at a volume concentrations of 0.03 and Re=20,000