A wind power tower cylinder equal life design method based on local thickening of fragments and wind power tower cylinder

Abstract

The application discloses a wind power tower drum equal life design method based on local thickening of fragments and a wind power tower drum, and relates to the technical field of wind power generation. The technical scheme points of the application are as follows: all the bearing accessories that need to be welded in the tower drum are arranged in a predetermined sector region in the ring direction, and only the local thickening is carried out on the region of the drum wall, the adverse effect of the fatigue strength grade reduction caused by welding is actively constrained and limited in a definite local range, then the cross-section modulus of the local region is increased by increasing the wall thickness of the local region, so as to reduce the stress amplitude under the working load, the equivalent fatigue life of the local thickening region after the welding accessories can be matched with the region not affected, so that the problem that the drum wall has to be thickened as a whole to ensure the life of the local welding points is solved, the steel consumption and the manufacturing cost are reduced under the premise of ensuring the safety of the tower drum in the whole life cycle.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, and more specifically, to a lifespan design method for wind turbine towers based on segmented local thickening, and to a wind turbine tower. Background Technology

[0002] As the capacity of individual wind turbine generators and the height of towers continue to increase, the fatigue loads acting on the tower structure are becoming increasingly severe. Load-bearing accessories that must be installed inside the tower, such as ladders for personnel access and tracks for supporting equipment lifting, must be securely connected to the tower body via fillet welds due to their functional and safety requirements. However, such welding introduces significant stress concentration into the base material, resulting in a substantial reduction in the fatigue strength grade (DC value) of the tower material in the welded area. This makes it a weak link that restricts the long-term service safety and reliability of the entire tower structure.

[0003] To address this problem, existing technologies have mainly developed two solutions, both of which have significant drawbacks. The first is a comprehensive thickening approach, which involves uniformly thickening the entire tower wall section where welding points are located. While direct, this method results in a severe overcapacity of material in areas unaffected by welding, leading to steel waste, increased costs, and poor economic efficiency. The second is a conventional decentralized local reinforcement approach, such as individually installing reinforcing plates or patches at each welding point of an accessory. While this method avoids overall thickening, it introduces numerous new, dispersed welding points when dealing with multiple accessories, essentially transforming a single fatigue risk point into multiple potential fatigue crack initiation points, without fundamentally improving the fatigue reliability spectrum of the structure. Furthermore, this approach is cumbersome in its process, increases the number of quality control points, and the design of the reinforcing plate size and thickness often relies on experience rather than precise calculations, leaving room for optimization in material usage and failing to achieve streamlined material configuration.

[0004] Therefore, how to study and design a life design method for wind turbine towers based on segmented local thickening that can overcome the above-mentioned defects is an urgent problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a lifespan design method and a wind turbine tower based on segmented local thickening. By actively constraining and limiting the adverse effect of reduced fatigue strength caused by welding to a specific local area, and then increasing the wall thickness of this local area to improve its section modulus, the stress amplitude under working load is reduced. This allows the equivalent fatigue life of the locally thickened area after welding accessories to match that of the unaffected area, thus solving the problem of having to thicken the entire tower wall to ensure the lifespan of local welded points. Under the premise of ensuring the safety of the tower throughout its entire life cycle, the amount of steel used and manufacturing costs are reduced.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: Firstly, a lifespan design method for wind turbine towers based on segmented local thickening is provided, including the following steps: Identify and determine all load-bearing accessories that need to be fixed by welding on the inner side of the tower wall; All the aforementioned load-bearing accessories are arranged in a predetermined sector-shaped area circumferentially upward on the tower wall; The cylinder wall within the predetermined sector area is locally thickened to make its thickness greater than that of the cylinder wall outside the predetermined sector area, thus forming a locally thickened area. The thickness increase value of the local thickening process is configured as follows: By increasing the section modulus of the locally thickened area, the working stress amplitude of the locally thickened area under the tower design load is reduced. The reduced stress amplitude compensates for the decrease in the fatigue strength level of the locally thickened area caused by welding the load-bearing attachment, so that the equivalent fatigue life of the locally thickened area after welding the load-bearing attachment matches the original fatigue life of the un-welded and un-thickened area.

[0007] Furthermore, the calculation process for the thickness increase value of the local thickening treatment is as follows: A finite element model including the weld of the load-bearing accessory was established, and the maximum working stress amplitude at the weld was calculated under the tower design load. Based on the fatigue performance curve of the tower material and the fatigue strength grade of the weld of the bearing accessory, determine the fatigue strength reduction value caused by welding; Based on the positive correlation between section modulus and wall thickness, the minimum wall thickness increase required to reduce the maximum working stress amplitude to no higher than the fatigue strength reduction value is calculated, and the minimum wall thickness increase is used as the thickness increase value of the local thickening treatment.

[0008] Furthermore, the process for determining the angle range of the predetermined sector area is as follows: The angle is determined by multiplying the total angle of the projection of all the aforementioned bearing accessories onto the circumferential direction of the cylinder wall by a coefficient of 1.2 to 1.5.

[0009] Furthermore, the process of locally thickening the cylinder wall within the predetermined sector area includes: using an arc-shaped steel plate with a target thickness, connecting it to the cylinder wall outside the predetermined sector area with the original thickness through a circumferential butt weld to form the locally thickened area.

[0010] Furthermore, at the joint between the arc-shaped steel plate and the adjacent cylinder wall, a single-sided bevel is machined, which smoothly transitions from the thickness of the adjacent cylinder wall to the thickness of the arc-shaped steel plate.

[0011] Furthermore, the slope of the single-sided inclined plane is between 1:4 and 1:5.

[0012] Furthermore, the method also includes: The surface of the circumferential butt weld between the locally thickened area and the adjacent cylinder wall is ground to improve the fatigue strength level of the weld.

[0013] Furthermore, the wind turbine tower is composed of multiple sections spliced ​​together along the axial direction. For adjacent sections, the local thickened areas of each section are staggered in the circumferential direction.

[0014] Furthermore, the angle at which they are offset from each other is 2° to 15°.

[0015] Secondly, a wind turbine tower is provided, which is designed and manufactured using a lifespan design method based on segmented local thickening of wind turbine towers as described in any one of the first aspects.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a lifespan design method for wind turbine towers based on segmented local thickening. All load-bearing accessories requiring welding within the tower are concentrated in a predetermined circumferential sector area. Only the wall of this sector is locally thickened. By actively constraining and limiting the adverse effect of reduced fatigue strength caused by welding to a specific local area, and then increasing the wall thickness of this local area to improve its section modulus, the stress amplitude under working load is reduced. This allows the equivalent fatigue life of the locally thickened area after welding accessories to match that of the unaffected area. This solves the problem of having to thicken the entire tower wall to ensure the lifespan of local welded points, reducing steel consumption and manufacturing costs while ensuring the safety of the tower throughout its entire lifespan.

[0017] 2. This invention establishes a finite element model including the weld seam of the attachment, accurately calculates the maximum working stress amplitude under the fatigue load spectrum, and determines the fatigue strength reduction value caused by welding by combining the material fatigue performance curve. Then, it calculates the minimum required wall thickness increase value, so that the determination of the local thickening amount is transformed from empirical estimation to accurate calculation based on the fatigue damage accumulation theory. This realizes the quantitative compensation of the fatigue strength reduction value by the stress amplitude reduction, ensures the accurate realization of the equal life design goal, avoids the safety hazards caused by insufficient thickening or the material waste caused by excessive thickening, and achieves the optimal lightweight design.

[0018] 3. By setting the angle range of the predetermined sector area to 1.2 to 1.5 times the total angle of the attachment projection, and setting a circumferential stagger angle of 2° to 15° for the thickened areas of adjacent upper and lower cylinder sections, this invention provides necessary process and safety margins for attachment arrangement and welding heat-affected zones, preventing secondary stress problems caused by excessive crowding. On the other hand, it breaks the continuous stiffness abrupt change zone that may be formed in the thickened area along the tower axis, avoiding the superposition and concentration of unfavorable stress fields in space, ensuring that the local reinforcement scheme will not introduce new weak links in the whole, thereby improving the uniformity and reliability of the overall stress on the tower.

[0019] 4. This invention uses an independent arc-shaped steel plate of the target thickness to connect with the original thickness cylinder wall to form a thickened area. A single-sided bevel with a slope of 1:4 to 1:5 is processed at the joint. Finally, the circumferential butt weld is ground. This ensures the manufacturing feasibility and superior performance of the locally thickened structure. The independent arc-shaped steel plate is easy to cut and roll, which is in line with the conventional manufacturing of large structures. The gentle bevel can smooth the force flow in the thickness transition area and greatly reduce the concentration of geometric stress. The weld grinding can eliminate surface defects and restore the fatigue strength of the butt weld itself to a high level close to that of the base material. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart from Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the overall structure in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the circumferential tensile force distribution of the tower under axial load in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the stress distribution principle of locally thickened cylinder wall under ideal conditions in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram showing the change in stress distribution on a local cylinder wall after welding the load-bearing accessory in Embodiment 1 of the present invention; Figure 6 This is a stress distribution cloud map of the locally thickened cylinder wall in Embodiment 1 of the present invention under a uniform tensile load; Figure 7 This is a stress distribution cloud map of the entire tower section under the action of overturning bending moment in Embodiment 1 of the present invention.

[0021] The attached diagram shows the markings and corresponding component names: 101. Locally thickened area; 102. Load-bearing accessories. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0023] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly or indirectly attached to that other component. When a component is referred to as being "connected to" another component, it can be directly or indirectly connected to that other component.

[0024] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] Example 1: A lifespan design method for wind turbine towers based on segmented local thickening, such as... Figure 1 and Figure 2 As shown, it includes the following steps: S1: Identify and determine all load-bearing attachments 102 that need to be fixed by welding on the inner side of the tower wall; S2: All load-bearing accessories 102 are arranged in a predetermined sector area facing upwards from the tower wall; S3: The cylinder wall within the predetermined sector area is locally thickened to make its thickness greater than that of the cylinder wall outside the predetermined sector area, forming a locally thickened area 101.

[0027] Specifically, the thickness increase value of the local thickening treatment is configured as follows: by increasing the section modulus of the local thickened area 101, the working stress amplitude of the local thickened area 101 under the tower design load is reduced. The reduced stress amplitude compensates for the decrease in the fatigue strength level of the local thickened area 101 caused by welding the load-bearing attachment 102, so that the equivalent fatigue life of the local thickened area 101 after welding the load-bearing attachment 102 matches the original fatigue life of the unwelded and unthickened area.

[0028] In step S1, based on the overall design drawings and functional requirements of the wind turbine generator set, all auxiliary structures that need to be installed inside the tower are reviewed and analyzed. This process, based on structural mechanics principles and safety regulations, identifies load-bearing attachments 102 that must be permanently fixed to the tower wall by welding due to large dynamic loads or extremely high requirements for connection reliability. In typical wind turbine tower structures, these load-bearing attachments 102 that must be welded mainly include internal ladders for maintenance personnel access and support structures supporting the tracks of elevators or manned platforms. Identifying and determining these attachments is a prerequisite for implementing subsequent segmented localized thickening designs. Its purpose is to accurately define all welding points that will be centrally arranged and require localized reinforcement, thereby ensuring that weak points in the fatigue life of the main tower structure are accurately located and effectively managed.

[0029] In step S2, all identified load-bearing attachments 102 are planned and concentrated within a continuous predetermined fan-shaped area along the circumferential direction of the tower wall. This predetermined fan-shaped area is the target area for subsequent local thickening treatment. In practice, designers need to adjust and closely arrange the welding anchoring positions of all load-bearing attachments 102, including ladder and elevator supports, in the circumferential unfolded diagram or 3D model of the tower, ensuring they all fall within a central angle of [missing information]. Within the fan-shaped area. The fundamental purpose of the centralized arrangement strategy is to bring together multiple welding points that might otherwise be scattered throughout the entire circumference of the tower, leading to multiple reductions in fatigue strength, into a localized area, thereby enabling the negative impact of welding on the fatigue performance of the main body to be managed regionally and compensated in a centralized manner.

[0030] For the angle range of the predetermined sector area The determination is based on the design calculations of the attachment geometry, including engineering safety margins. First, it is necessary to measure or calculate the central angle corresponding to the projected width of each load-bearing attachment 102 on the circumferential direction of the tower wall. Then, these projected angles of all attachments are summed to obtain the theoretically minimum total projected angle. This angle represents the minimum space required to accommodate all accessories under ideal, close-packed arrangement. However, in practical engineering, to avoid accessories being too crowded together and affecting installation, operation, and maintenance, and to leave sufficient spacing for the weld heat-affected zone to prevent stress fields from superimposing and producing more adverse effects, it is necessary to... Based on this, a certain layout margin is added. Therefore, the final determined angle range of the predetermined sector area is... It is necessary to refer to the minimum total projection angle according to this theory. This is determined by multiplying by a margin coefficient k selected in the range of 1.2 to 1.5, i.e. .

[0031] In step S3, the cylinder wall within the predetermined sector area is locally thickened to make its physical thickness greater than the original cylinder wall thickness outside the area, thereby forming a locally thickened area 101 with higher cross-sectional bending resistance on the tower.

[0032] The required increase in thickness for localized thickening is precisely calculated based on fatigue life and other life design principles. The determination of this thickness increase is essentially a closed-loop design logic that compensates for material performance losses through structural stiffness. It utilizes the geometrically positive correlation between section modulus and wall thickness to offset the fatigue strength reduction caused by welding. The specific calculation model is as follows.

[0033] First, a finite element model of the tower, including the detailed weld of bearing attachment 102, is established. Then, the tower design load spectrum is applied to the model, and the reference maximum working stress amplitude at the root of the weld of bearing attachment 102 is extracted, denoted as... The reference maximum working stress amplitude is a stress amplitude reference value calculated using a basic mechanical model before considering the amplification of the local stress concentration factor at the weld joint. Because the heat effect of welding alters the microstructure of the local material and introduces residual stress, leading to a reduction in the fatigue strength grade of that area, a maximum allowable stress amplitude limit needs to be determined during the design phase, denoted as [missing value]. .

[0034] According to the principles of structural mechanics, the section bending modulus of the tower wall under bending conditions... It is closely related to its geometric dimensions. For a hollow cylindrical tower, its section bending modulus is... It can be calculated using the following formula: ; in, Represents the outer diameter of the cylinder. This represents the thickness of the cylinder wall.

[0035] When the wall thickness within a predetermined sector area is increased from the original thickness through local thickening... Increase to target thickness Subsequently, the flexural modulus of the section in this region was correspondingly changed from... Increase to External design load bending moment amplitude Under the condition that remains unchanged, the actual working stress amplitude at the weld It will be reduced according to the following formula: .

[0036] The control objective of local thickening design is to improve... To reduce This ensures that the equivalent fatigue life after thickening and welding the attachments matches the fatigue life of the original region without welding and without thickening. This requires that the maximum working stress amplitude after thickening must be reduced to no higher than the allowable stress amplitude limit after welding reduction, i.e., satisfying the following equation constraint: .

[0037] By performing inverse calculations based on the above inequalities, the minimum wall thickness increase required to meet the equal life design requirements can be determined. ,Right now .

[0038] After determining the thickness increment, the specific local thickening manufacturing process is carried out according to the following steps: An arc-shaped steel plate with a target thickness is used, where the target thickness is the original thickness plus the calculated thickness increase. During the tower assembly stage, this thickened arc-shaped steel plate is placed in the predetermined fan-shaped area, ensuring its circumferential edges are tightly fitted to the outer wall steel plate with the original thickness. Subsequently, two complete circumferential butt welds are performed using automated welding technology to firmly connect the thickened arc-shaped steel plate to the original wall, thus forming the locally thickened area 101 in the physical structure.

[0039] To optimize the stress distribution in the transition area between the thickened zone and the original cylinder wall, and to eliminate geometric stress concentration caused by abrupt changes in thickness, a specific bevel design is incorporated at the butt joint. Specifically, at the butt edge between the thickened curved steel plate and the adjacent original thickness cylinder wall, a single-sided bevel is machined, smoothly transitioning from the original cylinder wall thickness to the thickness of the thickened curved steel plate. The slope of this single-sided bevel is preferably controlled between 1:4 and 1:5. A slope of 1:4 means that for every unit increase in thickness, the bevel extends horizontally by 4 units; a slope of 1:5 means that for every unit increase in thickness, the bevel extends horizontally by 5 units. This gentle transition design effectively reduces the stress concentration factor at the butt joint.

[0040] Furthermore, after completing the circumferential butt weld, post-treatment of the weld surface is necessary to further improve the fatigue performance of the main weld. The specific procedure involves using specialized weld grinding equipment to grind the excess weld height onto a smooth surface, ensuring it is flush with and smoothly transitions to the surrounding cylinder wall surface. This grinding process eliminates initial defects such as weld undercut and minor gaps, significantly improving the fatigue strength level of the weld at this location.

[0041] For wind turbine towers composed of multiple axially joined sections, when this design method is applied to all sections, the interaction between the sections must also be considered. To avoid the complete overlap of the locally thickened areas 101 of adjacent sections in the circumferential direction, which would result in a continuous stiffness abrupt change in the overall height of the tower, the positions of the locally thickened areas 101 of the upper and lower sections must be staggered during the design process. Specifically, the center lines of the predetermined fan-shaped areas of each adjacent section are staggered in the circumferential direction. The angle of this stagger is preferably controlled between 2° and 15°. This angle range effectively breaks the axial continuity of the locally thickened areas 101, preventing adverse stress superposition, and does not substantially affect the concentrated arrangement space of the load-bearing accessories 102, ensuring uniform stress distribution and manufacturing feasibility of the overall tower structure.

[0042] like Figure 3 and Figure 4 As shown, without thickening, the tensile force on the cylinder wall is evenly distributed, while the root of the weld in the bearing attachment 102 exhibits a significant high-stress zone due to stress concentration. After local thickening, the bending resistance of the thickened area is significantly enhanced. Under the same design load, the working stress amplitude in this area is significantly reduced, and the stress contour distribution is more gradual. This indicates that local thickening effectively offsets the reduction in material fatigue strength caused by welding heat effects by increasing the cross-sectional stiffness, verifying the design logic of compensating for material performance losses with structural stiffness.

[0043] like Figure 5 As shown, a detailed comparison of the stress distribution after welding the attachments and the locally thickened area 101 reveals that welding the load-bearing attachment 102 causes localized stress concentration at the contour plane. However, after localized thickening, combined with the transition design of the single-sided bevel, the stress contour lines transition from a steep abrupt change to a gentle transition. This is because the bevel makes the thickness change smoother, allowing the stress transmission path to diffuse naturally and avoiding stress concentration caused by a right-angle step-like abrupt change. The results confirm that this bevel design can control the stress concentration factor at a lower level, significantly optimizing the stress state of the transition area.

[0044] Furthermore, before grinding, the weld reinforcement and minor gaps can cause localized stress concentrations; after grinding, the weld surface is flush with and smooth with the base material, the stress contours are more evenly distributed, and the original stress peaks are effectively weakened. This post-processing eliminates the negative impact of weld defects on fatigue strength, making the fatigue performance of this area close to that of the base material, and providing reliable fatigue life protection for the locally thickened area 101.

[0045] like Figure 6 As shown, under uniform tensile stress, the stress distribution clearly demonstrates the stiffness compensation effect of local thickening. It can be seen that the stress values ​​are higher in the unthickened area (represented by dark red), while the stress values ​​significantly decrease in the thickened fan-shaped area (represented by orange-yellow). This proves that by increasing the local cross-sectional dimensions, the structure's resistance to deformation is enhanced, effectively attracting and dispersing tensile stress from the original weak areas to the thickened areas, achieving a benign stress redistribution.

[0046] like Figure 7 As shown, under the simulated overturning moment in a real-world environment, the contour plot reflects the crucial role of the thickened design in mitigating localized stress deterioration. In the thickened region on the tension side of the tower, the stress distribution is relatively gentle and the stress values ​​are reduced. This not only offsets the material degradation caused by welding heat effects but also avoids the severe stress concentration that might occur during right-angle transitions. This demonstrates that the design successfully ensures the structural integrity of high-stress areas such as the welded load-bearing accessory 102, effectively improving the overall fatigue resistance and load-bearing safety margin of the tower.

[0047] Example 2: A wind turbine tower, which is designed and manufactured using a lifespan design method based on segmented local thickening of wind turbine towers as described in Example 1.

[0048] Working principle: This invention concentrates all the load-bearing attachments 102 that need to be welded inside the tower in a predetermined fan-shaped area in the circumference, and only locally thickens the cylinder wall in this area. By actively constraining and limiting the adverse effect of the decrease in fatigue strength level caused by welding to a clear local range, and then increasing the wall thickness of this local area to increase its section modulus, thereby reducing its stress amplitude under working load, the equivalent fatigue life of the locally thickened area 101 after welding attachments can match that of the unaffected area. This solves the problem of having to thicken the cylinder wall as a whole to ensure the life of local weld points, and reduces steel consumption and manufacturing costs while ensuring the safety of the tower throughout its entire life cycle.

[0049] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lifespan design method for wind turbine towers based on segmented local thickening, characterized in that, Includes the following steps: Identify and determine all load-bearing accessories (102) that need to be fixed by welding on the inner side of the tower wall; All the load-bearing accessories (102) are arranged together in a predetermined sector area circumferentially upward on the tower wall; The cylinder wall within the predetermined sector area is locally thickened to make its thickness greater than that of the cylinder wall outside the predetermined sector area, forming a locally thickened area (101). The thickness increase value of the local thickening process is configured as follows: By increasing the section modulus of the locally thickened area (101), the working stress amplitude of the locally thickened area (101) under the tower design load is reduced. The reduced stress amplitude compensates for the decrease in the fatigue strength level of the locally thickened area (101) caused by welding the bearing attachment (102), so that the equivalent fatigue life of the locally thickened area (101) after welding the bearing attachment (102) matches the original fatigue life of the unwelded and unthickened area. The calculation process for the thickness increase value of the local thickening treatment is as follows: Establish a finite element model including the weld of the bearing attachment (102), and calculate the maximum working stress amplitude at the weld under the tower design load; Based on the fatigue performance curve of the tower material and the fatigue strength grade of the weld of the bearing accessory (102), the fatigue strength reduction value caused by welding is determined; Based on the positive correlation between section modulus and wall thickness, the minimum wall thickness increase required to reduce the maximum working stress amplitude to no higher than the fatigue strength reduction value is calculated, and the minimum wall thickness increase is used as the thickness increase value of the local thickening treatment.

2. The lifespan design method for wind turbine towers based on segmented local thickening as described in claim 1, characterized in that, The process for determining the angle range of the predetermined sector area is as follows: The angle is determined by multiplying the total angle of the projection of all the said bearing attachments (102) in the circumferential direction of the cylinder wall by a coefficient of 1.2 to 1.

5.

3. The lifespan design method for wind turbine towers based on segmented local thickening as described in claim 1, characterized in that, The process of locally thickening the cylinder wall within the predetermined sector area includes: using an arc-shaped steel plate with a target thickness and connecting it to the cylinder wall outside the predetermined sector area with the original thickness through a circumferential butt weld to form the locally thickened area (101).

4. The lifespan design method for wind turbine towers based on segmented local thickening as described in claim 3, characterized in that, At the joint between the arc-shaped steel plate and the adjacent cylinder wall, a single-sided bevel is machined, which smoothly transitions from the thickness of the adjacent cylinder wall to the thickness of the arc-shaped steel plate.

5. The lifespan design method for wind turbine towers based on segmented local thickening as described in claim 4, characterized in that, The slope of the single-sided inclined plane is between 1:4 and 1:

5.

6. The lifespan design method for wind turbine towers based on segmented local thickening as described in claim 3, characterized in that, The method also includes: The surface of the circumferential butt weld between the locally thickened area (101) and the adjacent cylinder wall is ground to improve the fatigue strength level of the weld.

7. The lifespan design method for wind turbine towers based on segmented local thickening as described in claim 1, characterized in that, The wind turbine tower is composed of multiple sections spliced ​​together along the axial direction. For adjacent sections, the local thickened areas (101) of each section are staggered in the circumferential direction.

8. The lifespan design method for wind turbine towers based on segmented local thickening as described in claim 7, characterized in that, The angles at which they are offset from each other are 2° to 15°.

9. A wind turbine tower, characterized in that, The wind turbine tower is designed and manufactured using a lifespan design method based on segmented local thickening of wind turbine towers as described in any one of claims 1-8.

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