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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6. Natural-based composite materials Experiments using natural fibre-reinforced polymers have shown characteristics such as lightweight, low density, low cost, non-abrasive, biodegradability, and renewable nature, which cannot be obtained using synthetic fibre. Therefore, manufacturers plan on shifting to natural fibre-reinforced composites as an alternative material for the synthetic fibres currently used in wind turbine blades. Despite having suitable properties, during the primary manufacturing of natural fibre-reinforced composites, poor adhesion between fibres and matric is one of the biggest challenges to overcome. It could lead to internal defects and low blade performance. According to this, with chemical treatment, the composite's mechanical strength and dimensional stability can be improved and, thus, could be ideal for turbine blades. The main components of a flax fibre consist of cellulose, hemicellulose, wax, lignin, and pectin, in varying quantities. Cellulose, hemicellulose, and lignin are essential components that determine the physical properties of the fibres (Kulatunga et al., 2022). Cellulose is the stiffest and strongest organic constituent in the fibre. However, cellulose is a semicrystalline polysaccharide with a large amount of hydroxyl group, giving hydrophilic nature to natural fibre when used to reinforce hydrophobic matrices. The result is an inferior interface and poor resistance to moisture absorption. This calls for fibre or matrix modification to improve the mechanical properties of the composite. This enables flax to be widely considered as reinforcement in a composite. This section represents the simulation tests done on a 5 kW turbine blade using SolidWorks and ANSYS with different materials. This simulation compares E-glass / Epoxy and Carbon / Epoxy property materials with materials strengthened by flax fibre, namely, Flax, S-Glass / Polypropylene, and Flax, Carbon / Polypropylene. As a result of the static study, the extreme behavior distribution of the wind turbine blade at a wind speed of 6 m/s was obtained. Von mises stress distribution, maximum displacement, and strain distribution of the blades for the proposed materials are shown in Table 5. 6.1. Flax composites

Table 5. Von mises stress distribution, maximum displacement, and strain distribution of the blades for the proposed materials

Flax, S glass/Polypropylene

Flax, Carbon/Polypropylene

Parameters

E-glass/Epoxy

Carbon/Epoxy

Maximum Stress (vonMises) (N/m 2 ) Maximum Displacement (mm)

1.379×10 9 2.673×10 4 2.673×10 4

1.018×10 9 5.40×10 3 5.171×10- 2

1.438×10 9 2.596×10 -1 8.175×10 -6

7.336×10 6 8.917×10 -3 1.42 ×10 -6

Maximum Strain (-)

Flax, S-glass/Polypropylene, and Flax, Carbon/Polypropylene are proposed as alternative materials in this project, and the materials were tested on blades through Finite Element Analysis and fatigue study. The above test results were obtained based on the chosen material properties. Results from the static study show that flax, S glass/polypropylene, and carbon/polypropylene can create stiffer blades with better mechanical properties. High stress concentrations, mechanical strength, dimensional stability, and other internal defects in the proposed composite materials can be improved using chemical treatments and better manufacturing technics. This could also improve the blade’s fatigue life and fatigue damage with the submitted material. Bamboo is one of the natural materials being intensively studied to substitute this synthetic fibre since they possess a higher strength-to-weight ratio. Bamboo can be used in composites as a natural fibre reinforcement in polymer matrices that are petroleum based. Such composites are also called Bamboo Fibre Reinforced Polymers. Bamboo is a material with a high potential for reinforcement in fibre-reinforced polymers. It has 60% cellulose with high lignin content; this characteristic property makes bamboo fibres a reinforcement in various polymer matrices. Holmes et al. (2009) compared the mechanical properties of bamboo and wood veneer laminate with birch 6.2. Bamboo composites