PSI - Issue 48

Muhammad Rizky Arga Wijaya et al. / Procedia Structural Integrity 48 (2023) 41–49 Wijaya et al. / Structural Integrity Procedia 00 (2023) 000–000

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concern is to reduce the cost so that composites can be used in products and applications that currently do not justify the cost. At the same time, they want to improve the performance of the composite, such as by making them more resistant to impact. Most composites are made up of just two materials. One material (the matrix or binder) binds together a cluster of fibres or fragments of a much stronger material, and the second material (the reinforcement) surrounds these fibres or fragments. Kulatunga et al. (2022) explained that manufacturers have decided to use composite material in designing wind turbine blades due to the following reasons,  High strength – to withstand gravity and other extreme loads.  High fatigue resistance and reliability – to ensure stable function for a service life of 20–25 years.  Low weight – to minimize the effect of gravitational forces and the load exerted on the tower.  High stiffness – to ensure stability and the orientation of the blade during operation. The mechanical and physical properties of fibrous composite materials are beneficial compared to other constructional materials of wind turbine blades. The significant advantages of this type of material are low weight and high strength. Therefore, wind turbine blades built with composite materials have much less weight than traditional constructions. 4. Conventional composite materials The most common type of composite material used in current turbine blade designs is glass fibre-reinforced polymer composites (GFRP) and carbon fibre-reinforced polymer composites (CFRP). This is due to their high stiffness and strength, excellent formability, ability to be tailored according to the desired orientation and position, and lightweight properties. The composite can have two or more types of reinforcements or matrix hybridization with some nanoparticles. Hybrids are conceptually fabricated to take advantage of all the constituent reinforcements (Shukla et al., 2015). As glass fibres have low specific strength and specific modulus, some volume fraction of carbon fibres (having high specific strength and modulus) should be incorporated into GFRP composite to enhance the mechanical properties and result in a better composite compared to GFRP. But due to the low strain to failure and the high cost of carbon fibres, a balance should be maintained between the cost and performance of the resulting composite. The mechanical properties of E-glass fibre, carbon fibre, and epoxy are shown in Table 1. Carbon fibres are used within turbine blades to optimize stiffness-to-weight ratios as blade lengths increase in size (Cherrington et al., 2012). Carbon fibres are a promising alternative to glass fibres, as they show high modulus, lower density, and high tensile strength compared to E-glass, which results in forming thinner, longer blades. Several tests have proven that carbon fibres are susceptible to misalignments and waviness under heavy loads, which could reduce fatigue and compressive strength. Due to this condition, the use of carbon fibres in wind turbine blades has been limited. 5. Advanced Materials: Nanocomposites Muhammed et al. (2020) analyzed that glass fibre/epoxy composites are preferred for constructing wind turbine blades. In this work, samples of SiO2 and Al2O3-based nanocomposites with different compositions were fabricated, tested, and compared with the traditional glass fibre/epoxy matrix composite. This work was done in four major stages. First stage deals with fabricating different composites with different percentages of nanomaterials. Following the methodology reported in the literature, each nanomaterial is added in four different weight percentages (1%, 2%, 3%, 4%). The details of the composites fabricated are given in Table 2. For nanocomposite fabrication, glass fibre has been opted as the reinforcement material and epoxy resin as the matrix. The epoxy resin used in this study is AW106. Table 1. Mechanical Properties of E-glass fibre, carbon fibre, and epoxy. Material E-Glass Carbon Epoxy Tensile Strength (MPa) Young`s Modulus (GPa) Density (g/cm 3 ) 2000 2900 80 2.58 525 3.5 2 85 1.5–10