In fact, tower tubes account for about 20 percent of the cost of a wind turbine. Despite the fact that the tower itself has a simpler form of loading compared to the blades, the height of one hundred meters puts heavier loads on the tower itself (especially at the base of the tower). The forces on the tower are primarily the gravity of the fan assembly and the lateral forces of the wind. As far as gravity is concerned, just make sure you have enough cross-sectional area to withstand it. However, as far as lateral forces are concerned, the tower is a fixed bottom ? beam? A little force on the header will create a large bending moment at the bottom.
This bending moment may damage the bottom structure. Therefore, this structure, similar to a cantilever beam, would be strengthened at the fixed end.? ? The beam? itself will also be specially designed. In order to increase the lateral bending resistance of the tower, the bottom will be larger than the top. Ideally, this variable cross-sectional size will allow the internal stresses to be distributed evenly. This will make full use of the material to maximize its load-carrying capacity and also reduce the deadweight of the structure. It was very windy that day. However, the strong winds should not have been the main cause. At the start of a wind turbine project, the local meteorological resources will be investigated. The level of wind is obviously an important parameter in the design of wind turbine structures. Therefore, although the wind was strong that day, it is not considered extreme weather. The level of wind should still be within the design limits.
The tower loading capacity of the first (lower) stage is sufficient. If the cause lies in the first stage, then the entire tower will fall as a whole and the upper tower will essentially not disconnect. Overall, the stress distribution is essentially uniform because the tower structure has a variable cross-section. However, since the tower is manufactured in sections, the connections in that section are the weak point of the tower. The small holes around the tower are connection holes, which are secured by bolts and other connectors during the installation process. In the installation specification, these connectors are precision connectors and a special torque wrench is required to install them for optimum torque: they are not too large to not damage the connector, and they are not too small to make the connection unsafe.
But these connectors are still the weak link. During the operation of a wind turbine, the wind is not constant but pulsating, and the direction is not unique. For the tower, the direction of the wind is completely random. This form of wind, acting on the blades, is then transferred to the tower, which itself will swing back and forth in the wind, which can be fatal to the connectors. With this oscillation, the connectors may loosen. Once loose, the oscillation will increase, which is a vicious cycle. In addition, when the connector itself swings back and forth, it is subjected to cyclical loads, which are prone to metal fatigue, thus reducing its load-carrying capacity. After a long period of time, it will disconnect and there will be a connection between the first stage and the second stage. Obviously broken, this is likely to be a problem with the connector here.