Buckling calculation method for fragmented tower

Abstract

The invention relates to a buckling calculation method for a fragmented tower. The buckling calculation method comprises the following steps: establishing a finite element model for the fragmented tower; lBA analysis is conducted on the finite element model, a static buckling analysis result of the fragmented tower is obtained, and the static buckling analysis result comprises critical buckling factors; performing MNA analysis on the finite element model to obtain a plastic reference resistance ratio of the fragmented tower; wherein in the MNA analysis, the tower bottom limit load loaded to the finite element model is determined according to a critical buckling factor obtained by the LBA analysis; geometric defect correction buckling calculation is conducted through the critical buckling factor and the plastic reference resistance ratio, and a designed buckling resistance factor is obtained; according to the designed buckling resistance factor, whether the fragmented tower meets the buckling checking requirement or not is judged, a finite element modeling method is applied, and a linear elasticity analysis method and a material nonlinear analysis method are combined for calculation, so that it can be guaranteed that the buckling checking result is more accurate and reliable.

Description

Technical Field

[0001] The present application relates to the technical field of segmented tower design, and in particular to a segmented tower buckling calculation method. Background Art

[0002] With the continuous progress of wind power development technology, the continuous expansion of application scale, and the maturing of the supporting system of the industrial chain, the entire wind power industry has entered the era of parity. The industry competition is particularly fierce, which puts higher requirements on each complete machine manufacturer, and the importance of technology cost reduction is highlighted. At present, large-scale onshore megawatt models have become the mainstream response plan of major complete machine manufacturers. However, the large-scale wind turbines have also posed challenges to the various requirements of the supporting structure. The large-scale units have brought about an increase in the aerodynamic thrust and pitch bending moment at the top of the tower, and the increase in the height of the tower has led to an increase in the force arm at the bottom of the tower. The combination of the two has greatly increased the bending load at the bottom of the tower. This can be dealt with by increasing the diameter of the steel tower and increasing the bending modulus of the section, but land transportation restricts the design of large-diameter steel towers. In response to this, the design method of the segmented tower (steel tower) was born. The segmented tower adopts a modular design, and each single tower section is composed of multiple prefabricated plates. Among them, the tower wall segments are connected by longitudinal flanges.

[0003] The introduction of the segmented tower is aimed at solving the problems of height limit, width limit and overweight in the transportation process, thereby further solving the problem of increased design cost caused by the tower design diameter limit, and can meet the use of restricted areas of transportation routes such as mountains and hills. Although the segmented segments have longitudinal flanges, which can be regarded as cylinder stiffeners to a certain extent, which is conducive to buckling design, but at the same time, due to the existence of longitudinal flanges and the weak connection areas caused by the tower segmentation, the overall stress of the segmented tower is relatively complex. Therefore, a safer and more reliable buckling design assessment method is needed for strength verification, which puts forward new requirements for the tower buckling calculation method. Summary of the invention

[0004] The present application provides a segmented tower buckling calculation method to solve the problem in the prior art that the segmented tower forms new weak areas due to the longitudinal flange and the tower segment petals, which puts higher requirements on the buckling strength verification of the tower.

[0005] According to a buckling calculation method for a segmented tower provided in the present application, the segmented tower has a longitudinal flange connected to a cylinder wall, and the method includes: S10, establishing a finite element model for the segmented tower; S20, perform LBA analysis on the finite element model to obtain the static buckling analysis results of the segmented tower. The static buckling analysis results include: critical buckling factor ; S30, perform MNA analysis on the finite element model to obtain the plastic reference resistance ratio of the segmented tower In the MNA analysis, the tower bottom limit load applied to the finite element model is based on the critical buckling factor obtained by the LBA analysis. Sure; S40, using the critical buckling factor and plastic reference resistance ratio Perform geometric defect correction buckling calculations to obtain the design buckling resistance factor; S50: Determine whether the segmented tower meets the buckling check requirement based on the designed buckling resistance factor.

[0006] In some embodiments, in step S20 and step S30, in LBA analysis and MNA analysis, the following two conditions need to be loaded: The moment buckling condition occurs at the connection between the longitudinal flange and the cylinder wall, and the torsional buckling condition occurs on the cylinder wall; when loading the moment buckling condition, the condition is loaded every 10-15° along the circumference of the cylinder wall.

[0007] In some embodiments, in step S20, the tower bottom load applied in the LBA analysis includes a resultant moment and a resultant force: , , , , and ; In step S30, the ultimate tower bottom load applied in the MNA analysis includes the resultant moment and the resultant force: , , , , and ; in, represents a pre-given load factor, =n , n is the magnification factor, and its value is greater than or equal to 1.

[0008] In some embodiments, in step S10, a finite element model is established for a segmented tower, including: The high-order three-dimensional twenty-node solid structural element SOLID186 is used to simulate the main body of the segmented tower, and the multi-point constrained rigid beam or rigid rod element MPC184 is used to simulate the rigid load transfer from the center loading point at the bottom of the segmented tower to the upper end face of the longitudinal flange at the top of the tower.

[0009] In some embodiments, in step S10, establishing the finite element model further includes: defining material parameters of the finite element model; the material parameter definition includes: determining the yield strength according to the wall thickness of the segmented tower, and determining the elastic modulus according to the material of the segmented tower.

[0010] In some embodiments, in step S20, in the LBA analysis, the mesh of the finite element model is divided into: the unit mesh size of SOLID186 is controlled to 50-80 mm, and 2-3 layers of mesh are set in the thickness direction of the cylinder wall of the segmented tower.

[0011] In some embodiments, in step S30, in the MNA analysis, the mesh of the finite element model is divided into: in the area where the analysis object is located, the unit mesh size of SOLID186 is controlled at 50-80 mm, and 2-3 layers of mesh are set in the direction of the wall thickness of the segmented tower; in the remaining areas, the unit mesh size of SOLID186 is controlled at 100-200 mm, and 1-2 layers of mesh are set in the direction of the wall thickness of the segmented tower.

[0012] In some embodiments, in step S20, in the LBA analysis, the buckling eigenvalues ​​and buckling modes of the first 10 orders are extracted. If the buckling instability at the target analysis point does not occur in the first 10 orders, the buckling factor extracted at the 10th order is used as the critical buckling factor. ; If buckling instability occurs at the target analysis point within the first 10 orders, the minimum buckling eigenvalue corresponding to the buckling instability is extracted as the critical buckling factor of the target .

[0013] In some embodiments, in step S40, the critical buckling factor and plastic reference resistance ratio Perform geometric defect correction buckling calculations to obtain the design buckling resistance factor, including: The buckling reduction factor is determined according to the following formula : ,when (1) ,when ......................(2) ,when .....................................(3) in, is the overall relative slenderness ratio, is the relative slenderness ratio of the axial compression limit, is the relative slenderness ratio of the plastic limit, is the elastic defect reduction factor, is the plastic range coefficient in buckling interaction, is the buckling interaction index; In the above formula, the overall relative slenderness ratio Determined by the following formula: ........................................(4) Characteristic buckling resistance factor Determined by the following formula: .........................................(5) Design Buckling Resistance Factor Determined by the following formula: .........................................(6) in, is the material safety factor.

[0014] In some embodiments, in step S50, judging whether the segmented tower meets the buckling check requirement according to the designed buckling resistance factor includes: The buckling strength of the segmented tower is calculated using the LBA / MNA calculation method. The criteria for determining whether the segmented tower meets the buckling check requirements are: like , The buckling check requirements are met.

[0015] The technical solution of the present application, in the calculation method for the buckling of a segmented tower, establishes a finite element model for the segmented tower, performs LBA analysis (linear elastic analysis) and MNA analysis (material nonlinear analysis) on the finite element model, and combines the results of static buckling analysis with the results of nonlinear buckling analysis of plastic materials to comprehensively address the technical difficulties of the segmented tower, such as the large number of weak areas and increased diversity of buckling behaviors caused by the existence of longitudinal flanges. Finally, the critical buckling factor obtained by the two analyses is and plastic reference resistance ratio , perform geometric defect correction buckling calculation, and obtain the final design buckling resistance factor. With this design buckling resistance factor, the buckling strength verification of the segmented tower is realized, and the verification result is safer and more reliable. In this way, the design requirements of the segmented tower for buckling strength can be met, so as to give full play to the advantages of the segmented tower in overcoming the height limit, width limit and overweight problems in the production process of traditional large towers, and promote the widespread application of segmented towers. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0018] Figure 1 A schematic diagram showing the steps of a method for calculating buckling of a segmented tower according to an embodiment of the present application is shown; Figure 2 A schematic diagram of the execution flow of the method for calculating buckling of a segmented tower according to an embodiment of the present application is shown; Figure 3 A schematic diagram of local mesh division of the longitudinal flange of the finite element model in the segmented tower buckling calculation method according to an embodiment of the present application is shown; Figure 4 A schematic diagram of flange bolt mesh division of a finite element model in a segmented tower buckling calculation method according to an embodiment of the present application is shown; Figure 5 A schematic diagram of the overall grid division of a segmented tower of a finite element model in a segmented tower buckling calculation method according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0019] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0020] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0021] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways, rotated 90 degrees or in other orientations, and the spatially relative descriptions used herein are interpreted accordingly.

[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] Figures 1 to 5 An embodiment of the segmented tower buckling calculation method of the present application is schematically shown.

[0025] like Figures 1 to 5 As shown, the present application discloses a buckling calculation method for a segmented tower, wherein the segmented tower has a longitudinal flange connected to the barrel wall, thereby increasing weak areas such as the tower barrel-longitudinal flange connection and the tower segment splitting area, and increasing the diversity of buckling behavior. Figure 1 As shown, the method includes: Step S10: establishing a finite element model for the segmented tower.

[0026] This step is to establish a corresponding finite element model based on the three-dimensional physical model of the segmented tower, and the finite element model can reflect the multi-node structural characteristics of the segmented tower, as well as the rigid load transfer method from the central load point at the bottom of the tower to the upper end face of the longitudinal flange at the top of the tower. The establishment of the finite element model and the model analysis can be based on existing analysis software. For example, in some embodiments of the present application, the finite element model is established and analyzed using ANSYS Workbench finite element software. This software is a prior art that is well known and available to those skilled in the art, so its operation process is not described in detail here.

[0027] Step S20, perform LBA analysis on the finite element model to obtain the static buckling analysis results of the segmented tower, the static buckling analysis results include: critical buckling factor .

[0028] LBA analysis refers to linear elastic buckling analysis, which is used to predict the theoretical critical load of an ideal structure. The analysis results include buckling (load) factor, buckling mode shape and relative stress distribution, etc. It can not only verify whether buckling instability occurs in the ideal structure, but also output the distribution of the most dangerous areas to mark the target areas of buckling instability that need to be focused on on the segmented tower.

[0029] Step S30, perform MNA analysis on the finite element model to obtain the plastic reference resistance ratio of the segmented tower In the MNA analysis, the tower bottom limit load applied to the finite element model is calculated based on the critical buckling factor obtained by the LBA analysis. Sure.

[0030] MNA analysis refers to material nonlinear analysis, which introduces plasticity factors and is closer to reality. It can realize nonlinear static analysis with gradually increasing loads. Applied to MNA analysis, the ultimate tower bottom load required for MNA analysis can be determined quickly and effectively, thereby improving the accuracy of the analysis and the calculation efficiency.

[0031] Step S40, using the critical buckling factor and plastic reference resistance ratio The geometric defect corrected buckling calculation is performed to obtain the design buckling resistance factor.

[0032] According to the European standard for steel structure design DIN EN 1993-1-6: 2017, etc., it is necessary to perform correction calculations on the buckling results combined with geometric defects in order to ultimately obtain a reliable design buckling resistance factor for buckling strength verification.

[0033] Step S50: determining whether the segmented tower meets the buckling check requirement based on the designed buckling resistance factor.

[0034] Through the above-mentioned method design, in the buckling calculation method of the segmented tower, the embodiment of the present application establishes a finite element model for the segmented tower, performs LBA analysis (linear elastic analysis) and MNA analysis (material nonlinear analysis) on the finite element model, and combines the static buckling analysis results with the nonlinear buckling analysis results of plastic materials to comprehensively deal with the technical difficulties of the segmented tower having more weak areas and increased diversity of buckling behaviors due to the existence of longitudinal flanges. Finally, the critical buckling factor and plastic reference resistance ratio obtained from the two analyses are used to perform geometric defect correction buckling calculations to obtain the final design buckling resistance factor. The buckling strength verification of the segmented tower is achieved by means of the design buckling resistance factor, and the verification result is safer and more reliable. As a result, the design requirements of the segmented tower for buckling strength can be met, thereby giving full play to the advantages of the segmented tower in overcoming the height limit, width limit and overweight problems in the production process of traditional large towers, and promoting the widespread application of segmented towers.

[0035] In some embodiments of the present application, the applicant discovered during the analysis that there are two prominent buckling behaviors in the segmented tower: longitudinal buckling behavior at the longitudinal flange connection, which may potentially occur at the connection between the longitudinal flange and the barrel wall; and transverse barrel wall torsional buckling behavior, which may potentially occur at the barrel wall itself. The former buckling behavior occurs in the moment buckling condition, and the latter buckling behavior occurs in the torque buckling condition, so the moment buckling condition and the torque buckling condition need to be fully considered in the analysis.

[0036] Therefore, in some embodiments of the present application, in step S20 and step S30, in both LBA analysis and MNA analysis, the following two conditions need to be loaded: the moment buckling condition occurring at the connection between the longitudinal flange and the cylinder wall, and the torsional buckling condition occurring on the cylinder wall. Among them, when loading the moment buckling condition, due to the presence of the longitudinal flanges of each tower section, the condition needs to be loaded every 10-15° along the circumference of the cylinder wall. As for the torsional buckling condition, since there is no asymmetric structure, it is not necessary to consider the angle application.

[0037] In some embodiments of the present application, in step S20, the tower bottom load loaded in the LBA analysis includes a resultant moment and a resultant force: , , , , and Among them, xyz represents the three-axis direction, M is the resultant moment, and F is the resultant force. The resultant moment and resultant force are calculated from the actual working conditions and are used to load into the finite element model for analysis and simulation. The loading position is the center of the bottom of the segmented tower.

[0038] In step S30, the ultimate tower bottom load applied in the MNA analysis includes the resultant moment and the resultant force: , , , , and .

[0039] in, represents a pre-given load factor, =n , n is the magnification factor, and its value is greater than or equal to 1.

[0040] Since the plasticity factor is introduced in the MNA analysis, the ideal structure is closer to the actual structure, and the ultimate tower bottom load is also greater. Therefore, the critical buckling factor obtained in the LBA analysis is used in this application. It is used to assist in determining the ultimate tower bottom load of MNA analysis. The value of n is obtained according to actual calculations, so as to select the resultant moment and resultant force of the original scale multiple according to actual conditions, or further select the resultant moment and resultant force after the scale multiple is enlarged. This can improve the accuracy of the calculation and effectively improve the calculation efficiency of MNA analysis and simulation.

[0041] In some embodiments of the present application, in step S10, a finite element model is established for a segmented tower, including: using a high-order three-dimensional twenty-node solid structure unit SOLID186 to simulate the main body of the segmented tower, and using a multi-point constrained rigid beam or rigid rod unit MPC184 to simulate the rigid load transfer from the center loading point at the bottom of the segmented tower to the upper end face of the longitudinal flange at the top of the tower. The SOLID186 unit has twenty nodes and a quadratic displacement mode, which can well simulate irregular structures. The MPC184 unit is used to simulate the rigid constraint between two deformable bodies to simulate the process of rigid structure transmitting force and moment.

[0042] In some embodiments of the present application, in step S10, establishing the finite element model further includes: defining material parameters for the finite element model. The material parameter definition includes: determining the yield strength according to the wall thickness of the segmented tower, and determining the elastic modulus according to the material of the segmented tower. For example, according to the segmented tower wall thickness of 16-40 mm, the yield strength is determined to be 345 MPa, and according to the steel material of the segmented tower, the elastic modulus E is determined to be 210 GMpa.

[0043] In some embodiments of the present application, in the LBA analysis, the mesh of the finite element model is divided into: the unit mesh size of SOLID186 is controlled at 50-80 mm, and 2-3 layers of mesh are set in the thickness direction of the cylinder wall of the sliced ​​tower. Because this application requires more refined analysis and simulation operations, the unit mesh size should not be too large, and the number of mesh layers should be set moderately.

[0044] In some embodiments of the present application, in step S30, the requirements of both computational efficiency and computational accuracy should be considered in the MNA analysis. Therefore, the mesh of the finite element model in the MNA analysis is divided into: in the area where the analysis object is located, the unit mesh size of SOLID186 is controlled at 50-80 mm, and 2-3 layers of mesh are set in the thickness direction of the cylinder wall of the sliced ​​tower to be consistent with the LBA analysis and ensure the fineness of the model analysis; in the remaining areas, the unit mesh size of SOLID186 is controlled at 100-200 mm, and 1-2 layers of mesh are set in the thickness direction of the cylinder wall of the sliced ​​tower to reduce the unit mesh size in the invalid area, reduce the number of mesh layers, and thus reduce the amount of calculation. Reference Figures 3 to 5 As shown, a schematic diagram of the grid division at the longitudinal flange of the segmented tower of the present application, a schematic diagram of the grid division of the flange bolts and a schematic diagram of the overall grid division of the segmented tower are respectively shown.

[0045] In some embodiments of the present application, in step S20, in the LBA analysis, the extraction of the analysis and calculation results should follow the following principles: extract the buckling eigenvalues ​​and buckling modes of the first 10 orders. If the buckling instability at the target analysis point does not occur in the first 10 orders, the buckling factor extracted at the 10th order is used as the critical buckling factor. ; If buckling instability occurs at the target analysis point within the first 10 orders, the minimum buckling eigenvalue corresponding to the buckling instability is extracted as the critical buckling factor of the target .

[0046] In some embodiments of the present application, in step S30, in the MNA analysis, the extraction of the analysis results follows the following principles: extract the displacement, plastic strain and time sub-step generated by the target analysis section under the tower bottom limit load, draw the relationship curve between the plastic load and the tower top displacement of the segmented tower, and obtain the plastic reference resistance ratio through the relationship curve .

[0047] In some embodiments of the present application, in step S40, the critical buckling factor is used and plastic reference resistance ratio Perform geometric defect correction buckling calculations to obtain the design buckling resistance factor, including: The buckling reduction factor is determined according to the following formula : ,when (1) ,when ............(2) ,when .....................................(3) in, is the overall relative slenderness ratio, is the relative slenderness ratio of the axial compression limit, is the relative slenderness ratio of the plastic limit, is the elastic defect reduction factor, is the plastic range coefficient in buckling interaction, is the buckling interaction index.

[0048] In the above formula, the overall relative slenderness ratio Determined by the following formula: ........................................(4) Characteristic buckling resistance factor Determined by the following formula: .........................................(5) Design Buckling Resistance Factor Determined by the following formula: .........................................(6) in, is the material safety factor. In practical applications, the material safety factor Selected according to IEC 61400-1-2019 (international standard for design requirements of wind power generation systems).

[0049] Therefore, the critical buckling factor can be obtained according to LBA analysis Ratio of plasticity benchmark resistance obtained by MNA analysis The buckling calculation with geometric defect correction is carried out to obtain the design buckling resistance factor, which is used for the buckling strength verification of the segmented tower.

[0050] In some embodiments of the present application, judging whether the segmented tower meets the buckling check requirement according to the design buckling resistance factor includes: calculating the buckling strength of the segmented tower using the LBA / MNA calculation method, and judging whether the segmented tower meets the buckling check requirement according to the criterion: like , The buckling check requirements are met.

[0051] Specifically, the calculation of the parameters in the above formulas can be seen in the following formulas and tables: a. Elastic defect reduction coefficient Calculation: Dimensionless length parameter , calculated according to formula (7): ..................................(7) in, is the wall thickness, is the length of the barrel section, It is the median diameter.

[0052] The definition of a short cylindrical shell is as follows: ..................................(8) The definition of the medium-length cylindrical shell is as follows: ..................................(9) The definition of a long cylindrical shell is as follows: ..................................(10) Elastic defect reduction factor Determined by the following formula (11): ..................................(11) here, Calculate according to formula (12) ..................................(12) Wherein, Q is a manufacturing quality parameter, and the manufacturing quality parameter Q is selected according to the following Table 1.

[0053] Table 1 Manufacturing quality parameter Q value

[0054] b. Axial compression limit relative slenderness ratio Selection and calculation of For short cylindrical shells and medium-length cylindrical shells, the axial compression limit relative to the slenderness ratio is as follows: ..................................(13) For a long cylindrical shell that satisfies the following conditions, as shown in formulas (14), (15), and (16): ..................................(14) ..................................(15) ..................................(16) in, is the yield strength of the material.

[0055] Axial compression limit slenderness ratio Calculate according to the following formula (17): ..................................(17) in, represents the axial stress component caused by the bending moment, Represents the axial stress component caused by external load.

[0056] c. and Determination In the embodiments of the present application, , . And the calculation of cylinder axial buckling and The values ​​of are consistent.

[0057] d. Plastic limit relative slenderness ratio Calculation The plastic limit relative slenderness ratio in the axial stability calculation of cylindrical shells is as follows: .................................(18) refer to Figure 2 As shown in the flow chart, Figure 2 The schematic diagram of the process of using ANSYS Workbench finite element software to perform the calculation method for the buckling of the segmented tower frame of the present application is shown. After the processes 201 to 206, the buckling analysis in the analysis software can be realized, and the required data can be obtained to complete the geometric defect correction, so as to perform accurate and reliable buckling strength verification of the segmented tower frame. Of course, it can be understood by those skilled in the art that other different finite element software can be selected to perform the calculation method of the present application, and the operation process may be adjusted, which is known to those skilled in the art and will not be described in detail here.

[0058] In summary, the technical solution of the present application, in the calculation method for the buckling of a segmented tower, establishes a finite element model for the segmented tower, performs LBA analysis (linear elastic analysis) and MNA analysis (material nonlinear analysis) on the finite element model, and combines the results of static buckling analysis with the results of nonlinear buckling analysis of plastic materials to comprehensively address the technical difficulties of the segmented tower, such as the large number of weak areas and increased diversity of buckling behaviors caused by the existence of longitudinal flanges. Finally, the critical buckling factor obtained by the two analyses is and plastic reference resistance ratio , perform geometric defect correction buckling calculation, and obtain the final design buckling resistance factor. With this design buckling resistance factor, the buckling strength verification of the segmented tower is realized, and the verification result is safer and more reliable. In this way, the design requirements of the segmented tower for buckling strength can be met, so as to give full play to the advantages of the segmented tower in overcoming the height limit, width limit and overweight problems in the production process of traditional large towers, and promote the widespread application of segmented towers.

[0059] In the preferred embodiments of the present application, suitable finite element mesh division methods are determined for LBA analysis and MNA analysis, respectively, and the diversity of buckling behavior caused by the existence of the longitudinal flange is fully considered. The loading moment conditions and torque conditions are comprehensively considered in the analysis and simulation calculation, further improving the reliability of the safety analysis results of the segmented tower.

[0060] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for calculating the buckling of a segmented tower, wherein the segmented tower has a longitudinal flange connected to a cylinder wall, characterized in that: The method includes: S10, establishing a finite element model for the segmented tower; S20, performing LBA analysis on the finite element model to obtain a static buckling analysis result of the segmented tower, wherein the static buckling analysis result includes: a critical buckling factor ; S30, performing MNA analysis on the finite element model to obtain the plastic reference resistance ratio of the segmented tower ; Wherein, in the MNA analysis, the tower bottom limit load applied to the finite element model is based on the critical buckling factor obtained by the LBA analysis Sure; S40, using the critical buckling factor and the plastic reference resistance ratio Perform geometric defect correction buckling calculations to obtain the design buckling resistance factor; S50: Determine whether the segmented tower meets buckling check requirements according to the designed buckling resistance factor.

2. The method for calculating the buckling of a segmented tower according to claim 1, characterized in that: In step S20 and step S30, in the LBA analysis and the MNA analysis, the following two working conditions need to be loaded: A bending moment buckling condition occurs at the connection between the longitudinal flange and the cylinder wall, and a torsional buckling condition occurs on the cylinder wall; wherein, when the bending moment buckling condition is loaded, the condition is loaded every 10-15° along the circumference of the cylinder wall.

3. The method for calculating buckling of a segmented tower according to claim 1, characterized in that: In step S20, the tower bottom load applied in the LBA analysis includes a resultant moment and a resultant force: , , , , and ; In step S30, the ultimate tower bottom load applied in the MNA analysis includes a resultant moment and a resultant force: , , , , and ; in, represents a pre-given load factor, =n , n is the magnification factor, and its value is greater than or equal to 1.

4. The buckling calculation method of a segmented tower according to claim 1, characterized in that: In step S10, a finite element model is established for the segmented tower, including: A high-order three-dimensional twenty-node solid structural unit SOLID186 is used to simulate the main body of the segmented tower, and a multi-point constrained rigid beam or rigid rod unit MPC184 is used to simulate the rigid load transfer from the center loading point at the bottom of the segmented tower to the upper end face of the longitudinal flange at the top of the tower.

5. The method for calculating the buckling of a segmented tower according to claim 4, characterized in that: In step S10, establishing the finite element model further includes: defining material parameters of the finite element model; the material parameter definition includes: determining the yield strength according to the wall thickness of the segmented tower, and determining the elastic modulus according to the material of the segmented tower.

6. The method for calculating the buckling of a segmented tower according to claim 4, characterized in that: In step S20, in the LBA analysis, the mesh of the finite element model is divided as follows: the unit mesh size of the SOLID186 is controlled to be 50-80 mm, and 2-3 layers of mesh are set in the thickness direction of the cylinder wall of the segmented tower.

7. The method for calculating buckling of a segmented tower according to claim 4, characterized in that: In step S30, in the MNA analysis, the mesh of the finite element model is divided into: in the area where the analysis object is located, the unit mesh size of the SOLID186 is controlled at 50-80 mm, and 2-3 layers of mesh are set in the direction of the wall thickness of the sliced ​​tower; in the remaining areas, the unit mesh size of the SOLID186 is controlled at 100-200 mm, and 1-2 layers of mesh are set in the direction of the wall thickness of the sliced ​​tower.

8. The method for calculating buckling of a segmented tower according to claim 4, characterized in that: In step S20, in the LBA analysis, the buckling eigenvalues ​​and buckling modes of the first 10 orders are extracted. If the buckling instability at the target analysis point does not occur in the first 10 orders, the buckling factor extracted at the 10th order is used as the critical buckling factor. If buckling instability occurs at the target analysis point within the first 10 orders, the minimum buckling eigenvalue corresponding to the buckling instability is extracted as the critical buckling factor of the target .

9. The method for calculating buckling of a segmented tower according to claim 1, characterized in that: In step S40, the critical buckling factor is used and the plastic reference resistance ratio Perform geometric defect correction buckling calculations to obtain the design buckling resistance factor, including: The buckling reduction factor is determined according to the following formula : ,when (1) ,when .........................(2) ,when .....................................(3) in, is the overall relative slenderness ratio, is the relative slenderness ratio of the axial compression limit, is the relative slenderness ratio of the plastic limit, is the elastic defect reduction factor, is the plastic range coefficient in buckling interaction, is the buckling interaction index; In the above formula, the overall relative slenderness ratio Determined by the following formula: ........................................(4) Characteristic buckling resistance factor Determined by the following formula: .........................................(5) Design Buckling Resistance Factor Determined by the following formula: .........................................(6) in, is the material safety factor.

10. The method for calculating buckling of a segmented tower according to claim 1, characterized in that: In step S50, judging whether the segmented tower meets the buckling check requirement according to the designed buckling resistance factor includes: The buckling strength of the segmented tower is calculated using the LBA / MNA calculation method. The criteria for determining whether the segmented tower meets the buckling check requirements are: like , The buckling check requirements are met.

Images