Faculty of Engineering and Built Environment
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Item An investigation into a magnetic compaction technique for composite manufacturing(2023-09) Salot, Yazid; Gilpin, MarkFiber reinforced polymer composites are an aerospace and defense material. These materials are widely used in the production of components and parts which require high weight to strength ratios or corrosion resistance. The automotive, aero, marine as well as sporting industries are increasingly requiring components with such characteristics. This has led to an increase in demand in the composite industry. A composite is a material made from a combination of fiber reinforcement and resin. The reinforcement is generally made of Glass, Carbon or Aramid fiber which is woven in a fabric. While resins are typically thermoplastic such as polyester, vinyl ester, phenolic and epoxy. The fiber and resin are combined and compacted together in order to manufacture an item. There are various manufacturing techniques which are utilized to produce fiber reinforced composite components. Many items are manufactured using closed moulding techniques. The process involves the combining of fabric preform with a liquid resin within the mould cavity. After a certain period the component is removed from the mould. The strength, stiffness (mechanical properties) and strength to weight ratio of a composite material are affected by voids (air pockets) and the component’s thickness. Both the air voids and thickness are influenced by compaction during the manufacturing process. Increasing compaction during moulding improves the material properties and ultimately the final product, component or part. This research is aimed at investigating the possibility of utilizing magnetic compaction in fiber reinforced composite manufacturing. The desired technique will be intended to offer improved compaction without requiring any tooling modifications. The proposed technique would fall into the category of the light closed mould compression techniques which utilizes Glass Reinforced Plastic (GRP) tooling. This technique will also attempt to address certain issues experienced in light closed mould techniques. The magnetic compaction technique would be investigated in an effort to offer a scalable technique which has an improved fiber volume fraction and mechanical properties. Currently no closed mould techniques implement magnetic compaction. The research will review the combination of light closed moulding techniques and the working principles of magnetism.Item Performance of nanoclay infused plant fibre-reinforced hybrid biocomposites under impact loading(2023-05) Moyo, Mufaro; Kanny, Krishnan; Mohan, Turup PanduranganThis study focused on developing sustainable and lightweight plant fibre-reinforced hybrid bionanocomposites with enhanced impact properties. Such biocomposites are envisaged as potential replacements for the non-sustainable conventional synthetic fibre-reinforced polymer composites in applications requiring resistance to impact loading. In this work, the hybrid bionanocomposites were fabricated using polylactic acid (PLA) as the biopolymer, kenaf fibre nonwoven mat as the biofibre and clay nanoparticles of different loadings as fillers. Clay nanoparticle loading of 0, 3, 5, and 7 wt% were used. The resultant kenaf/nanoclay/PLA hybrid bionanocomposites were tested for thermal decomposition, tensile properties, flexural properties, dynamic mechanical properties and impact properties. The medium velocity impact resistance was tested using a high speed gas gun. The structure-property relationships were characterised using a scanning electron microscopy (SEM), energy dispersive x-ray (EDX), fourier transform infrared (FTIR) spectroscopy and x-ray diffraction (XRD) techniques. The resultant kenaf/nanoclay/PLA hybrid bionanocomposites were found to be considerably lightweight with a positive buoyancy. Clay nanoparticle loading of 5 wt% was found to be the optimum. The results showed that the thermal stability and dynamic mechanical properties of the hybrid bionanocomposites improved with the addition of clay nanoparticles. The tensile strength and the flexural strength of the hybrid bionanocomposites improved by 19.1% and 9.8%, respectively, when clay nanoparticles were added. Infusion with clay nanoparticles improved the Young’s modulus and flexural modulus by 41.5% and 34%, respectively. Addition of clay nanoparticles improved the energy absorption capability and impact strength of the hybrid bionanocomposites under low velocity impact loading by 92.9% and 98.7%, respectively. The clay nanoparticles also considerably enhanced the medium velocity impact resistance of the hybrid bionanocomposites as evidenced by improvement of the perforation threshold limit, energy absorption capability and damage resistance. The perforation threshold limit improved to 37 m/s which was equivalent to 42.3% increase, the energy absorption capability improved by 109% and the resistance to damage improved by 26.5%. The dominating damage mechanisms for the kenaf/nanoclay/PLA hybrid bionanocomposites were observed to be shear, matrix cracking, matrix crushing, fibre fracture, fibre/matrix debonding, shear plugging, bulging, interface debonding and delamination. Since the resistance to impact loading was established to be in the medium velocity impact range, the novel hybrid bionanocomposites have a potential to replace the non-biodegradable synthetic fibre-reinforced polymer composites in cushioning against secondary debris or blasts in the medium velocity impact range. They are also suitable for lightweight applications such as in the transportation sector for lightweight mass transit systems and unmanned aerial vehicles (UAV). The novel biodegradable kenaf/nanoclay/PLA hybrid bionanocomposite materials developed in this work are potential materials for the future which can positively contribute to sustainability and attainment of Sustainable Development Goals (SDG’s).Item Hybrid syntactic foam core cased natural-glass fibre sandwich composite(2023-05) Afolabi, Olusegun Adigun; Kanny, Krishnan; Mohan, Turup PanduranganComposite materials comprised of two separates with different properties to form a single material that reflect the properties of the combined materials. Syntactic foam composites (SFC) are made from the combination of hollow glass microspheres and epoxy resin. They are lightweight and used as a core in the hybrid sandwich composite. Hollow glass microspheres (HGM) are high strength microballoons that provide closed cell porosity and help to reduce material weight. SFCs made of HGM, and resin matrix are used as the core in sandwich composite material and reinforced with natural or synthetic fiber materials. The sandwich syntactic foam composite (SSFC) has a wide range of applications in the marine, aerospace, structural, and automobile industry. Therefore, it is important to investigate their physical, mechanical, thermal, and morphological properties to achieve high strength and low density. Most of the previous work in literature employed the use of different fillers and core materials in sandwich composite but are limited in strength because of their high density. In this study, a single HGM filler was employed as heterogeneous and homogenous by varying into four different particle sizes to investigate the effect of these particle sizes on the mechanical and physio-mechanical properties of the SFC used as the core in the SSFC. The effect of wall thickness and radius ratio of the HGM on the microstructural properties of SFC was also determined. The heterogeneous and homogeneous SFC was fabricated by degassing method mixing the epoxy matrix with HGM filler, the filler was varied into five-volume fractions of 5, 10, 15, 20, and 25%. The functional group of the HGM filler and the neat epoxy was determined and compared with that of the SFCs fabricated using Fourier Transform Infrared Spectroscopy (FTIR). The results showed that the filler contain various functional groups such as hydroxyl group, phenol-OH, aldehyde C-H group, aromatic proton, epoxy group, which enhanced the bonding process. It was determined that the intensity of the SFCs for all the volume fractions increased more than the neat epoxy due to the shifts in the peaks representing the filler and the matrix groups. The physical (density, water absorption, buoyancy) properties and the mechanical (hardness, tensile, flexural, and impact) properties of the SFCs improved significantly compared with the neat epoxy. The Scanning Electron Microscopy (SEM), Dynamic Mechanical Analysis (DMA), and Thermo-gravimetric Analysis (TGA) were also used to determine the morphological structure, the viscoelastic properties, and degradation temperature of the HGM and the neat epoxy and compared with the fabricated SFCs. The surface of the HGM showed the microballoons in their different sizes before separation. The surface of the SFCs showed the epoxy matrix, matrix porosity, microballoons porosity, and microballoons structure in their mixed state. It was an indication of good interaction between the epoxy matrix and the HGM filler using degassing processing method. The DMA showed improved storage and loss modulus values by 9% and above 100% respectively compared to the neat epoxy and the TGA showed better glass transition Tg values of 4.5% and 2.7% at 20% and 55% weight loss respectively compared to the neat epoxy. This indicated that good interaction and interfacial bonding existed between HGM and the epoxy matrix and because of lower density and void content. The SFC was used as the core to fabricate a lightweight sandwich syntactic foam composite (SSFC). The SSFC was made into four different orientations (kenaf-SFC-kenaf, as KK; glass –SFCglass, as GG; glass/kenaf – SFC – kenaf/glass, as GK; and kenaf/glass –SFC- glass/kenaf, as KG) using kenaf and glass fibers as reinforcement. The physical properties (density, water absorption capacity, and buoyancy), mechanical properties (hardness, tensile, compression, and flexural), morphological properties (SEM), and acoustic properties were determined. The porosity of KK increased by 21.6% because the kenaf fiber is less dense and more porous in terms of water absorption which makes it require higher buoyancy force to stay afloat. The mechanical properties results showed that GK and KG have the highest hardness, flexural and compressive strength of 70.2%, 74.4%, and 42.7% respectively, while GG has improved tensile strength of 210.96% increase than KK. The acoustic properties results showed that GG improved in sound level (P) dB by 24.1% compared to KK, while the sound pressure (Lp) dB does not show a significant difference in the SSFC. In conclusion, the degassing processing method of SFCs improved its physical and mechanical properties by reducing the density using particle distribution analysis (PSA) and particle variation analysis (PVA) with the aid of a gas pycnometer, and porosity values thereby making it a suitable core material for the sandwich composite. A novel sandwich syntactic foam composite (SSFC) material was fabricated by hybridizing the face-sheets in different layering pattens. The SSFC physical and mechanical properties improved significantly with the use of hybrid fibers. Hence, this study has demonstrated that for structural and marine purposes, hybrid fibers can perform better as reinforcement in the sandwich composite than using a single fiber.