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Composite laminate design is an important procedure in defining the mechanical properties of laminated composite structure to be used in multi-directional service loading application. Composite technologies or manufacturers who is lack of knowledge regarding the importance of laminate design, tend to develop a composite structure that will collapse or fail below the service requirement. The purpose of this study is to determine the effect of fiber orientation on flexural properties of the designed glass fiber reinforced epoxy laminated composite. Six sets of laminates with different fiber orientation and sequence were simulated using CompositeStar© software to determine its flexural properties. Samples were fabricated to verify the simulated data and were tested in accordance to ASTM D2344. Moreover, crack pattern within the samples after the flexural test is studied. From the simulated results, it shows that laminates which have fiber in tri-direction and quasi-direction display a higher flexural modulus and strength compared to laminates with fiber in uni-directional and bi-directional. In addition, data from tested fabricated laminates samples displayed the same modulus patterns against the simulated data, with variants from 8% to 35%. Additionally, it is found that samples with fiber in ±45 direction shows a transverse and shear cracking which prolonged the cracking propagation before the samples show a complete failure.

This work was carried out as a preliminary study of electrospun LiFePO4/CA fibers. Cellulose acetate (CA) and LiFePO4 solutions were prepared separately using mixed solvent of acetone and water, prior to the electrospinning process. Then, electrospinning parameters including solution concentration, distance tip to collector, pump rate, and needle diameter size were optimized. Brunauer Emmett Teller (BET) was used to determine the surface area of CA fibers. Viscosity of CA solution was obtained by viscometer. LiFePO4/CA fibers were stabilized and carbonized at different temperature. The surface morphology and microstructure of the obtained LiFePO4/ CA fibers were then characterized using scanning electron microscope (SEM). In this work, it is shown that different electrospinning parameter, solution concentration and solution viscosity gives different fibers diameter and distribution. Moreover, the stabilization and carbonization temperature of LiFePO4/CA fibers may also affect the fibers microstructure.

The limited shelf life of carbon prepreg waste (CPW) from component manufacturing restricts its use as a composite reinforcement fibre on its own. However, CPW can be recycled with glass fibre (GF) reinforcement to develop a unique remediate material. Therefore, this study fabricated (1) a glass fibre-carbon prepreg waste reinforced polymer hybrid composite (GF-CPW-PP), (2) a polypropylene composite (PP), (3) a carbon prepreg waste reinforced composite (CPW-PP), and (4) a glass fibre reinforced composite (GF-PP) and reported their degradation and residual tension properties after immersion in water. The polymer hybrid composites were fabricated via extrusion technique with minimum reinforce glass-carbon prepreg waste content of 10 wt%. The immersion test was conducted at room temperature using distilled water. Moisture content and diffusion coefficient (DC) were determined based on water adsorption values recorded at 24-h intervals over a one-week period. The results indicated that GF-PP reinforced composites retained the most moisture post-168 h of immersion. However, hardness and tensile strength were found to decrease with increased water adsorption. Tensile strength was found to be compromised since pores produced during hydrolysis reduced interfacial bonding between glass fibre and prepreg carbon reinforcements and the PP matrix.

This study investigated the effects of water ageing and low-velocity impact loadings on E-glass fibre/epoxy composite pipes subjected to monotonic internal pressure. The pipes, which consisted of six antisymmetric layers with (±55°)3 winding angles, were manufactured by the filament winding process. The specimens were cut from the pipes to the required test length. The specimens were then subjected to the ageing process by being immersed in 80 °C tap water for time intervals of 500, 1000, and 1500 h. Impact loadings of three different energy levels (5 J, 7.5 J, and 10 J) were applied, which were followed by monotonic burst tests. Scanning electron microscopy images were captured and the correlation between the ageing time and the level of impact energy on the pipes' burst strength was identified. The results indicated that the peak force and displacement increased as the impact energy increased. The monotonic burst test results revealed that the specimens that had been aged and were impacted by higher energy yielded lower burst strength. Weepage and eruption failures were observed depending on the applied impact energies. Keywords: Filament winding, GRE composite pipe, Ageing, Impact loading, Monotonic burst test

Transmission structures such as transmission towers or transmission poles were designed to endure multiple combinations of acting force. However, these current structures that were made from concrete and metal are heavyweight materials that cause difficulties in handling during assembly, maintenance and reinstallation purposes. The other problem is vandalism issues on the metallic bracing of the transmission towers. Glass fiber reinforced polymer, (GFRP) is a type of fiber reinforced composites that combine the continuous high strength reinforcing fiber material and lightweight properties of polymeric matrix, thus offers an alternative solution for those problems. In this paper, a laminate design of GFRP samples were simulated using CompositeStar© software to determine the mechanical strength and its reserve factor. The composite panels were varied in term of fiber direction and it was designed to withstand a distributed load of 5 kN service load in longitudinal (x-axis) and transverse (y-axis) direction on samples with thickness range between 4.00 to 4.20 mm. From the simulated results, it shows that the panels with fiber orientation in bi-direction and quasi-direction display a balance strength and acceptable reserve factor in both x-direction and y-direction. Therefore the properties and reserve factors of laminate design simulated from this software can be used as a benchmark in designing a laminated composite.

The effects of winding angle on the behaviour of glass/epoxy composite tubes under multiaxial cyclic loading were investigated. The performance of such composite tubes was studied using an indigenous automated test procedure that is compatible with the internal qualification requirements of the composite pipe manufacturers. Glass fibre reinforced epoxy (GRE) composite pipes with three winding angles, namely, [±45°]4, [±55°]4, and [±63°]4, were tested. A novel automated test rig was fabricated to accommodate five stress ratios, ranging from pure axial to pure hoop loadings. The cyclic pressure test was conducted until droplets of water were seen on the outer surface of the pipe. Failure envelopes were then constructed based on the first ply failure (FPF) points determined from the axial stress to hoop strain response at five stress ratios. Three functional failure modes, namely, tensile axial, weepage, and local leakage failures, were observed during the tests. The results indicate that each winding angle dominates a different optimum pressure loading condition, namely, [±55°]4 for pure hydrostatic loading, [±45°]4 for hoop to axial loading, and [±63°]4 for quad hoop to axial loading. The envelopes show a strong dependence on the stress ratio and winding angle. Keywords: Glass fibre reinforced epoxy (GRE), Ultimate Elastic Wall Stress (UEWS), First ply failure (FPF), Multiaxial stress ratio, Cyclic loading

This study investigates the effect of winding angle on the mechanical properties of kenaf fiber reinforced epoxy composite which is produced by filament winding technique. This study investigates the effect of 45° and 63° angle variations of fiber winding placement fixed by 2 layers using kenaf fiber and glass fiber as raw materials. Mechanical properties of the sample were determined by using tensile test (ASTM D3036), compressive test (ASTM D695) and 3-point flexural bending (ASTM D790). Both mechanical properties of kenaf fiber and glass fiber were compared to determine the possibility of kenaf fiber to replace glass fiber in composite industries in the future. From this study, all result showed that treated kenaf fiber has higher mechanical properties compared to untreated kenaf due to improvement of NaOH treatment on kenaf fiber. Result also has showed that higher winding angle, which is 63° has higher mechanical properties as compared to lower angle placement of 45° of the winding composites.

This paper discusses the the development of an automated pressure testing rig to perform a short term test; Ultimate Elastic Wall Stress (UEWS) for ±55 ̊ glass fibre reinforced epoxy (GRE) composite pipe under various stress ratios. The prototype is capable of determining the stress-strain response caused by the static and cyclic pressure. This developed rig is to provide an alternative solution for the current qualification procedure explained in ISO14692 through ASTM 2992. As part of the work, an automated testing rig powered by labview program is developed with the aid of pressure sensors, solenoid valves and strain gauges which are interfaced through hardware modules from National Instruments. The UEWS test for the five stress ratios namely pure hydrostatic (2H:1A), pure hoop (1H:0A), pure axial (0H:1A), hoop to axial (1H:1A) and quad hoop to axial loading (4H:1A) were performed upon the ±55° filament wound glass-reinforced epoxy pipes. The changes in the stress strain response are captured from the strain gauge measurements and the UEWS failure points are calculated for all the loading conditions. The failure envelope developed from the failure points can be used to predict the long term performance of the GRE pipes and provide the benchmark for the design of composite pipes under various stress ratios.

Fiber Metal laminates, FML, is a combination of metal with fiber/resin laminates and it is a well-known application in composite laminates due to its dimension stability and properties consistency. Generally, the strength of these laminates systems is much depends on the mechanical interlocking mechanism between the metal surface and the composite laminates. Therefore, surface treatment is needed to enhance the laminates strength. In this research, aluminum plates with different surface roughness were laminated with carbon-fiber/epoxy laminates. The strength of these hybrid systems was then characterized to study the effect of surface roughness on the interfacial strength. It shows that the higher surface roughness will result in better interfacial interaction between the metal surface and the fiber laminates.

Fibre-metal-laminated composites that consist of aluminium and carbon fibre/epoxy was widely use in engineering fields such as in aerospace and civil application. An issue arise for this laminate systems is that aluminium surfaces must be treated to ensure the effectiveness of load transfer mechanism in the interfacial region. In this research, the effect of anodized layer on the aluminium surface towards strength of the carbon fibre-aluminium-laminated composites was studied. Aluminium 6061-T6 was anodized using phosphoric acid as electrolyte and different anodizing voltage to produce different surface morphology. The surface roughness and morphology were determined via Atomic Force Microscopy and its wettability was determined by Static Contact Angle. Then, anodized aluminium was laminated with carbon fibre/epoxy system via vacuum bagging techniques. It shows that the strength of laminated composite with anodized surface increases up to 26% compared to laminates without anodized surfaces. Furthermore, the failure mechanism of laminated composite with anodized surface resulted in partial adhered failure instead of adhesive failure. These show that anodized surfaces contributes to the effectiveness of load transfer mechanism in fibre-metal-laminates composites.

The cure process and the mechanical properties of liquid polymethylmethacrylate grafted natural rubber (LMG30) modified epoxy have been studied. Addition of LMG30 significantly increased the fracture toughness and the impact strength of the epoxy resin. The fracture toughness increased up to 22 fold (17.3 MNm-3/2) when modified with 5 phr LMG30. The glass transition temperature however, decreases as the rubber content increases. The SEM analysis shows uniform dispersion of rubber particles within the epoxy matrix with average particle size between 0.4 to 0.8 0m in diameter.