wind turbine

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A wind turbine is a device that converts kinetic energy from the wind into electrical power. Small wind turbines we discussed for domestic use have fewer requirements to properties, but more considerations of cost compared to large wind turbine.

2.1 Blade material choice
According to its working principles, the blade materials of wind turbine not only have to face large aerodynamic, inertial and fatigue loads, but are now being designed to endure environmental effects such as degradation of surface, accumulation of dust particles, ice accretion on blades, insect collision on blades and moisture ingress [5]. The carbon-fiber has the highest tensile strength and modulus and can pose extremely high resistance to fatigue, corrosion and moisture which are all desired for wind turbine blade. Due to the high strength to weight ratio, lighter blades allow sensitivity to minor wind movements and a rapid response to wind gusts. Besides, lighter blades require less robust turbine and tower components, so the whole cost savings decrease the additional cost of carbon fiber [6]. However, this kind of cost saving is only effective on large wind turbines. On the contrary, the carbon fiber has disadvantages such as: low strain to failure, low impact resistance, high electrical conductivity and high cost. For the remote households or farms which need to use small wind turbines, the high cost of carbon fiber will increase the price of the whole wind turbine which is the biggest shortcoming. Specifically, the carbon fiber costs more than 10 times as much as E-glass fiber, which is also a feasible alternative (in Table 1). In conclusion, the carbon fiber is fully suitable as a blade material of large-scale wind turbine, but for domestic small wind tu...

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As for the attachment method, there are two main types of joint: mechanically fastened joints (bolted, riveted) and adhesively joints. The method of using screws which is applied in the project can be classify as mechanically fastened and uses friction between the joined parts to force them together. The joint is designed to allow load transfer between the components in such a way that the structure has the necessary performance. The benefits of bolted joint are lower installation costs, lower maintenance costs, increased productivity, lower fastener costs and flexibility. One problem is that wind turbines are fatigue machines—always vibrating and working to loosen their fasteners. Therefore, the lifetime of the bolted joint may need to be considered. Another problem is that with carbon-fiber and metal, galvanic corrosion can occur which is harmful to the machines.

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