Modeling method of irregular cracks in finite element analysis model of steel structural members

Abstract

The application discloses a modeling method of irregular cracks in a finite element analysis model of a steel structural member, randomly generates or generates irregular cracks according to a planned path, constructs the irregular cracks in a geometric model of the member through a series of cylinders which overlap each other, randomly determines the radius of each cylinder and the interval between the centers of two adjacent cylinders according to the crack width range, and randomly determines the relative orientation between the two adjacent cylinders; performs a Boolean operation on all the cylinders and the crack area to construct a geometric model of the member containing the irregular cracks; for a perfect area outside the crack area, maps the finite element grid of the perfect area, freely divides the finite element grid of the crack area, and obtains a finite element analysis model of the member containing the irregular cracks; the irregular crack shape determined by the random generation method is closer to the crack damage of a real structural member, and the model constructed is more accurate in evaluating the degradation law of the performance of the in-service structural member.

Description

Technical Field

[0001] This invention relates to finite element analysis models for steel structural components, particularly a modeling method for irregular cracks, applicable to structures such as flat plates and cylindrical shells built using SHELL and SOLID elements. Background Technology

[0002] Cracks are a common defect in ship and marine steel structures, typically occurring at discontinuous cross-sectional dimensions or welded joints. They gradually form under cyclic loading and exhibit irregular shapes. Crack formation exacerbates stress concentration in localized areas of the structure, severely weakening its ultimate load-bearing capacity. Accurately and reasonably assessing the residual ultimate strength of crack-damaged structures and examining the impact of crack parameters on the overall structural or component performance are essential for ensuring structural safety under normal service conditions, conducting risk assessments of aging structures, and developing relevant repair and maintenance measures.

[0003] The impact of crack damage on structures has received widespread attention, with numerous studies investigating crack propagation in both perfect and defective structures or components to predict their remaining life. However, in-depth research is still lacking regarding the degradation of the ultimate strength of structures or components after fatigue cracks occur. For example, Chinese Patent Publication No. CN101059407A proposes a method to calculate the crack propagation at each point along the crack front using the Paris formula, thereby determining the crack propagation trajectory and simulating a three-dimensional crack. However, this method requires complex fracture mechanics calculations and frequent mesh re-division when determining the crack. Furthermore, since crack propagation simulation and ultimate strength analysis require completely different element types, the cracks constructed by the above method are not suitable for finite element analysis of components after crack damage. Chinese Patent Publication No. CN105205223A proposes a method to simulate internal material defects by randomly arranging a large number of pores or cracks inside a component. This method aims to simulate the random distribution of material defects, but the constructed cracks are randomly distributed straight cracks, failing to reflect the irregular shapes of randomly propagating cracks in real engineering structures. Chinese patent publication CN110400362A proposes a method for identifying multiple cracks based on image processing technology, obtaining information about each crack and the intersection points between cracks, and then connecting and reconstructing the cracks using ABAQUS software to construct a two-dimensional finite element analysis model of the cracks. However, this method is only applicable to the finite element analysis of a specific cracked structure, and its analysis results depend on the accuracy of the image recognition method. In summary, existing technologies are not suitable for conducting finite element analysis of cracked structures or components, and cannot reveal the general laws governing the influence of cracks on the residual strength of structures or components.

[0004] In existing studies on the ultimate strength of crack-damaged structures, the finite element analysis models used to construct models simplify cracks into one or more narrow, elongated rectangular slits. This differs significantly from the irregular crack morphology caused by stress concentration in actual structures. The impact of this simplification of irregular cracks into narrow, elongated rectangular slits on the strength assessment results is unclear. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that the existing technology cannot accurately represent the true crack shape of the structure or component, and to provide a modeling method for irregular cracks in the finite element analysis model of steel structure components. This method can simulate the irregular cracks formed by the cumulative damage of actual steel structure components under cyclic loads, and more accurately predict the remaining strength of the steel structure under crack damage.

[0006] To achieve the above objectives, the present invention employs the following technical solution, comprising the following steps:

[0007] Step (1) Establish a global coordinate system O-XYZ based on the shape of the steel structure component, establish a geometric model of the component based on the geometric dimensions of the component, generate irregular cracks randomly or according to the planned path, establish a virtual plane rectangular coordinate system xoy with the center of the crack area of ​​the irregular crack as the origin of the coordinate system, and the x and y axes are consistent with the X and Y axes respectively. Take any quadrant of the coordinate system xoy as the crack start position.

[0008] Step (2) involves constructing irregular cracks in the geometric model of a component using a series of overlapping cylinders. The radius of each cylinder and the distance between the centers of two adjacent cylinders are randomly determined based on the crack width range. Then, the relative orientation between two adjacent cylinders is randomly determined.

[0009] Step (3) Create all cylinders in the crack zone, and perform Boolean operations between all these cylinders and the crack zone to construct a geometric model of the component with irregular cracks.

[0010] Step (4) On the geometric model of the component with irregular cracks, for the perfect area outside the crack zone, the finite element mesh of the perfect area is divided by mapping, and the finite element mesh of the crack zone is divided by free method, so as to obtain the finite element analysis model of the component with irregular cracks and complete the modeling.

[0011] Furthermore, the position of the first cylinder is determined based on the crack initiation position. The radii of the first and second cylinders are randomly generated within the crack width range. Starting from the center of the first cylinder, a center-to-center distance and azimuth angle are randomly generated to determine the center position of the second cylinder. Then, the third cylinder is generated starting from the second cylinder, and so on, to generate a series of overlapping cylinders.

[0012] Furthermore, a two-dimensional array CK(N,4) is defined to record the center coordinates and radius of each cylinder in the global coordinate system O-XYZ. Each row of data in the two-dimensional array CK(N,4) corresponds to the coordinates X, Y, Z and radius R of cylinder i generated when a crack is constructed, i∈n, n is the total number of cylinders, n≤N, and N is the length of the two-dimensional array. The generation of cylinders stops when the time is right; LCK is the crack length, d i It is the distance between the centers of two adjacent cylinders.

[0013] The beneficial effects highlighted by the present invention after adopting the above technical solution are:

[0014] (1) Unlike existing methods that simplify cracks into regular rectangular narrow slits, the irregular crack morphology determined by the random generation method is closer to the crack damage of real structural components.

[0015] (2) The finite element analysis model of irregular cracked components constructed in this invention can more accurately evaluate the degradation law of the performance of in-service structural components.

[0016] (3) This invention constructs irregular cracks along random or planned paths and uses random generation technology to construct irregular cracks in the finite element analysis model, making the performance evaluation of existing structures more accurate and applicable to the study of the residual strength problem of structures under crack damage. Attached Figure Description

[0017] Figure 1 This is a flowchart of the modeling method for irregular cracks in the finite element analysis model of steel structure components according to the present invention;

[0018] Figure 2 This is a coordinate diagram of an irregularly cracked plate.

[0019] Figure 3 for Figure 2 Enlarged view of part I in the middle;

[0020] Figure 4 for Figure 2 The geometric model of the irregularly cracked plate shown;

[0021] Figure 5 for Figure 2 The finite element analysis model of the irregularly cracked plate is shown.

[0022] Figure 6 For when Figure 2 The finite element analysis model obtained when irregular cracks are randomly generated on a flat plate according to a polygonal planning path;

[0023] Figure 7 For when Figure 2The finite element analysis model is obtained when irregular cracks are randomly generated on a flat plate following a curved planning path.

[0024] Figure 8 A diagram showing an irregularly cracked circular pipe and the extent of its cracked zone;

[0025] Figure 9 for Figure 8 Finite element analysis model of a circular tube with irregular cracks. Detailed Implementation

[0026] See Figure 1 The steel structure components, such as flat plates and cylindrical shells, exhibit irregular cracks that may arise randomly or along a planned path. Based on the shape of the steel structure component, a global coordinate system O-XYZ is established to obtain the key model parameters of the component. These parameters include the component's geometric dimensions, crack zone range, crack width range, crack length, and crack initiation location. Then, a geometric model of the component is established based on the stated geometric dimensions, and the crack zone and intact zone are segmented within the geometric model according to the stated crack zone range.

[0027] A virtual Cartesian coordinate system xoy is established with the center of the cracked area as the origin o. The directions of the x and y coordinate axes are consistent with the directions of the X and Y coordinate axes in the global coordinate system O-XY, respectively. Any quadrant of the virtual Cartesian coordinate system xoy is taken as the crack initiation position.

[0028] Irregular cracks in the component's geometric model are constructed using a series of overlapping cylinders. A two-dimensional array is defined to record the crack information in the component's geometric model. This crack information essentially refers to the center coordinates and radii of these cylinders in the global coordinate system O-XYZ.

[0029] Specifically, the two-dimensional array is defined as CK(N,4), where N is the length of the two-dimensional array. Each row of data corresponds to the coordinate position X, Y, Z and radius R of the cylinder i generated when constructing a crack, i∈n, where n is the total number of cylinders and n≤N. That is, CK(i,1)=X, CK(i,2)=Y, CK(i,3)=Z and CK(i,4)=R.

[0030] Since the number, size, and position of cylinders cannot be predetermined when randomly generating irregular cracks in cylinders, the length N of the two-dimensional array cannot be accurately determined in advance either. However, it can be estimated as follows: take half of the lower limit of the crack width range as the minimum distance between the centers of two adjacent cylinders in a series of overlapping cylinders, and then divide the crack length by this minimum distance to determine the length N of the two-dimensional array.

[0031] Specifically: Let the crack width range be [CK]. L CK U ], of which CK L CK is the lower limit value. U This is the upper limit. Therefore, the minimum distance between the centers of two adjacent cylinders is 0.5 * CK. L Let the crack length be LCK. Then the length N of the two-dimensional array is determined by the crack length LCK and the lower limit of the crack width CK. L Value determined: N = 2 * LCK / CK L .

[0032] When constructing irregular cracks in the geometric model of a component, firstly, based on the crack width range, randomly generate the radius of the first cylinder within the crack width range. Then, based on the crack initiation position, determine the position of the first cylinder, using the crack initiation position as the center position of the first cylinder. Subsequently, randomly generate the radius of the second cylinder within the crack width range, and using the center of the first cylinder as the starting point, randomly generate a center-to-center distance and azimuth angle. In this way, randomly determine the center position of the second cylinder adjacent to the first cylinder, and randomly determine the relative azimuth between the two adjacent cylinders.

[0033] Specifically: in [0.5*CK] L 0.5*CK U The radius of the first cylinder is randomly generated within the specified crack initiation zone. Then, the X, Y, and Z coordinates of this cylinder are randomly generated within the specified crack initiation zone. The information of the first cylinder is stored in two-dimensional arrays: CK[1][1], CK[1][2], CK[1][3], and CK[1][4]. Then, within [0.5*CK... L 0.5*CK U The radius of the second cylinder is randomly generated within the first cylinder. The radius of the second cylinder is compared with the radius of the first cylinder to obtain the smaller radius R. L and larger radius R U Define a radius interval [R] L R U ]; Generate a random number within this interval to represent the center distance d1 between the two overlapping cylinders.

[0034] In the azimuth interval [α] L ,α U A random azimuth angle α1 is generated within the range; this azimuth angle range is generally set to [-90°, 90°], and can be adjusted arbitrarily as needed. Taking the center of the first cylinder as the starting point, the position of the second cylinder is determined based on the distance d1 and the azimuth angle α1. The method for calculating the position coordinates of the second cylinder is as follows:

[0035] X = CK[1][1] + d1*COSα1,

[0036] Y = CK[1][2] + d1*SINα1,

[0037] Depending on the needs of subsequent modeling, the Z coordinate of the second cylinder can be taken as the bottom surface or inner surface of the component.

[0038] To determine whether the second cylinder is within the crack zone, if the generated second cylinder is too close to the crack zone boundary, an azimuth angle α1 should be randomly generated again to ensure it falls within the crack zone. Simultaneously, a distance threshold D is set to ensure the distance between the crack and the crack zone boundary is not less than this threshold D, thus avoiding affecting the quality of the finite element mesh in the crack zone.

[0039] Starting with the second cylinder, a third cylinder is generated in the same manner. This process is repeated to create a series of overlapping cylinders. When the error between the sum of the distances between the centers of the series of cylinders and the crack length is less than a pre-set target error, the crack length is considered to have met the requirement, and cylinder generation stops. This error can be set as the smaller of the radii of the first and last cylinders; where LCK is the crack length, and n ≤ N. The position coordinates and radius of each of these overlapping cylinders are stored in the aforementioned two-dimensional array.

[0040] All cylinders are created in the cracked area segmented by the geometric model of the component, and Boolean operations are performed between these cylinders and the cracked area to construct the geometric model of the component with irregular cracks.

[0041] On the geometric model of the component with irregular cracks, for the segmented perfect area, the mesh control size of the perfect area is set. First, the finite element mesh of the perfect area is divided using the mapping method, and then the finite element mesh of the cracked area is divided using the free method, so as to obtain the finite element analysis model of the component with irregular cracks and complete the modeling.

[0042] Two embodiments are provided below, which take a flat plate and a circular tube with irregular crack damage as examples, and implement the present invention using ANSYS finite element software.

[0043] Example 1

[0044] The steel structure component is a flat plate with irregular crack damage. The specific steps are as follows:

[0045] Step 1: See Figure 2 Using one corner of the flat plate as the origin of the coordinate system, for example... Figure 2A global coordinate system O-XYZ is established with the lower left corner of the flat plate's bottom surface as the origin. The geometric dimensions of the flat plate structure are: length 400mm (X direction), width 250mm (Y direction), and thickness 11mm (Z direction). The crack zone is defined as a rectangular crack zone abcd, where the coordinates of the four corner points of abcd in the XY plane are a(80,85), b(320,85), c(320,165), and d(80,165), respectively. The crack width CK ranges from [CK...]. L CK U = [3,4] mm. Crack length LCK = 150 mm. Determine the crack initiation location: With the center o of the crack zone abcd as the origin, and the coordinates of the origin o in the XY plane as (200, 125), establish a virtual Cartesian coordinate system xoy. The x and y directions of the local coordinate system xoy are parallel to the X and Y directions of the global coordinate system, respectively. The third quadrant of the local coordinate system xoy is taken as the crack initiation location.

[0046] Based on the flat plate structure, a geometric model of the flat plate is established, and the flat plate is divided into a cracked zone and a perfected zone. The cracked zone is a rectangular area abcd, and the area outside the rectangular area abcd is the perfected zone.

[0047] Step 2: Define a two-dimensional array. For example... Figure 3 As shown, the lower limit of the crack width is set to 0.5*CK. L =1.5mm is the minimum distance between the centers of the two overlapping cylinders.

[0048] Based on the lower limit value of crack width CK L Based on the crack length LCK, the length of the two-dimensional array N = 2 * LCK / CK is initially determined. L =100, and the two-dimensional array is defined as CK(100,4) based on the length N of the two-dimensional array. Each row of this two-dimensional array stores the center coordinates and radius information of a cylinder in the global coordinate system O-XYZ. For example, the two-dimensional arrays CK(1,1), CK(1,2), CK(1,3), and CK(1,4) store the X, Y, Z coordinates and radius of the first cylinder, respectively.

[0049] Step 3: Define a series of overlapping cylinders to construct the irregular crack. The specific steps are as follows:

[0050] (1) Based on the crack width range [CK] L CK U Given that the radius of the cylinder is [3,4] mm, the range of values ​​for the cylinder radius is determined to be [1.5,2]. This allows for the random generation of the first cylinder. Figure 3The first cylinder in the model has a radius R1 = Random(1.5,2) = 1.8576. Then, in the third quadrant of the xoy coordinate system, the X, Y, and Z coordinates of the center of the first cylinder are randomly generated as (131.5730, 121.2347, 11). The center coordinates of X, Y, and Z and the radius R1 are stored in two-dimensional arrays: CK[1][1] = 131.5730, CK[1][2] = 121.2347, CK[1][3] = 11, CK[1][4] = 1.8576.

[0051] (2) Within the radius range of [1.5, 2] of the cylinder, randomly generate a second cylinder, i.e. Figure 3 The second cylinder in the model has a radius R2 = Random(1.5,2) = 1.7549. Compared with the radius of the first cylinder generated in step (1), the minimum radius R is determined. L =1.7549 and the maximum radius R U =1.8576, thus determining the radius interval [R] L R U The center distance d1 is then generated as d1 = Random(1.7549, 1.8576) = 1.7862, as shown below. Figure 3 As shown in d1, it represents the center-to-center distance between the two overlapping cylinders.

[0052] (3) Within the set azimuth interval [α L ,α U [-60, 90] A random azimuth angle α1 = Random(-60, 90) = 50.81 is generated, for example. Figure 3 The azimuth angle α1 shown is given.

[0053] (4) Taking the center of the first cylinder as the starting point, determine the center position of the second cylinder based on the center distance d1 and the azimuth angle α1. The position calculation method is as follows:

[0054] X=CK[1][1]+d1*COSα1=132.7015,

[0055] Y=CK[1][2]+d1*SINα1=122.6192,

[0056] The Z-coordinate is taken as the coordinate Z = 0 at the bottom surface of the plate.

[0057] (5) Determine whether the second cylinder is within the crack zone abcd. Set a distance threshold D = 5mm to control the distance between the crack and the crack zone boundary to ensure the quality of the finite element mesh.

[0058] (6) Repeat steps (2) to (5) until the condition is met. When the time is reached, cylinder generation stops, resulting in a total of 86 overlapping cylinders (86 < 100).

[0059] Step 4: Based on the cylinder information stored in the two-dimensional array CK(86,4), set the height of the cylinders to 11mm, which is the thickness at the top of the plate, and establish the geometric model of all cylinders.

[0060] By performing a Boolean operation between the geometric model of the cylinder and the geometric model of the flat plate, a geometric model of the irregularly cracked plate is obtained, such as... Figure 4 As shown.

[0061] Step 5: Set the control size of the perfected zone to 15mm, generate the finite element mesh for the perfected zone, and then freely generate the finite element mesh for the cracked zone to obtain the finite element analysis model of the overall structure of the cracked plate, as shown below. Figure 5 As shown.

[0062] In the first step, when irregular cracks are randomly generated on the plate according to the broken line planning path, the finite element analysis model of the irregularly cracked plate obtained after performing steps one through five is as follows: Figure 6 As shown. In the first step, when irregular cracks are randomly generated on the plate according to the planned path of the curve, the finite element analysis model of the irregularly cracked plate obtained after the first to fifth steps is as follows. Figure 7 As shown.

[0063] Example 2

[0064] The steel structure component is a circular tube component with irregular crack damage. The specific steps are as follows:

[0065] Step 1: The geometric dimensions of the circular tube are: length 800mm, outer radius 60mm, and thickness 6.9mm; Crack zone range: the circular tube is unfolded along any generatrix on its outer surface to form... Figure 2 The plane shown ignores the influence of the tube thickness. The inner surface of the tube can be considered as the bottom surface of a flat plate, and the outer surface as the top surface. Therefore, the tube component can be unfolded into a flat plate component similar to that in Example 1. The rectangular crack region abcd has a length of 40π mm (corresponding to a central angle of 120°) and a height of 100 mm. The coordinates of the four corner points of the rectangle are a(10π, 350), b(40π, 350), c(50π, 450), and d(10π, 450). Figure 8 As shown; Crack length: LCK = 100mm; Crack width range: [CK] L CK U]=[3,4]mm; Crack initiation position: Establish a local coordinate system xoy with the center of the crack zone as the origin o, and take its third quadrant as the starting position. Establish the geometric model of the component with the bottom left corner of the unfolded plane as the origin of the global coordinate system O-XYZ, and divide the unfolded plane of the circular tube into the crack zone (rectangle abcd) and the perfect zone (the area of ​​the circular tube other than rectangle abcd), such as Figure 8 As shown.

[0066] Step 2: Define a two-dimensional array. Set the lower limit of the crack width to 0.5 * CK. L =1.5mm is taken as the minimum distance between the centers of the two overlapping cylinders, and the length of the two-dimensional array is initially determined to be N = 2*LCK / CK. L =66.67, after rounding, N=67, and the final two-dimensional array is defined as CK(67,4). Each row of this array stores the position and radius information of a cylinder. For example, CK(1,1), CK(1,2), CK(1,3), and CK(1,4) correspond to the X, Y, Z coordinates and radius of the first cylinder, respectively.

[0067] Step 3: Define a series of overlapping cylinders to construct the irregular crack. The specific steps are as follows:

[0068] (1) Based on the crack width range, the cylinder radius is determined to be [1.5,2]. The first cylinder radius R1 = Random(1.5,2) = 1.8361 is randomly generated. Then, in the third quadrant of the xoy local coordinate system mentioned in the first step, the X, Y, and Z coordinates of the first cylinder are randomly generated. The above information is stored in CK[1][1] = 51.4602, CK[1][2] = 389.6364, CK[1][3] = 60, and CK[1][4] = 1.8361 respectively.

[0069] (2) Within the range [1.5,2], randomly generate a second cylinder with a radius R2 = Random(1.5,2) = 1.5085. Compare this radius with the cylinder generated in step (1) to determine the radius of R. L =1.5085 and R U =1.8361, thus determining the interval radius [R] L R U Then, the center distance d1 = Random(1.5085, 1.8361) = 1.6272 is generated as the center distance between the two overlapping cylinders.

[0070] (3) In the interval [α] L ,α U ] = [-30, 90] Randomly generate an azimuth angle α1 = Random(-30, 90) = 65.09.

[0071] (4) Taking the center of the first cylinder as the starting point, determine the position of the second cylinder based on the distance d1 and the azimuth angle α1. The position calculation method is as follows:

[0072] X=CK[1][1]+d1*Cosα1=52.1455,

[0073] Y=CK[1][2]+d1*Sinα1=391.1122,

[0074] The Z-coordinate is taken from the coordinates of the inner surface of the circular tube, Z = 0.

[0075] (5) Determine whether the second cylinder is within the crack zone. Set a distance threshold D = 5mm to control the distance between the crack and the crack zone boundary, ensuring the quality of the finite element mesh.

[0076] (6) Repeat steps (2) to (5) above, until the condition is met. Stop generating cylinders; a total of 57 overlapping cylinders were generated (57 < 67).

[0077] Step 4: Based on the cylinder information stored in the 2D array CK(57,4), the height of the cylinders is uniformly set to 6.9mm. For the cylindrical shell, the modeling coordinate system is set to a cylindrical coordinate system, with its origin at the center of the end of the cylindrical tube; the position information of the cylinders in the 2D array CK(57,3) is converted to the cylindrical coordinate system to establish the geometric model of all cylinders. Boolean operations are then performed between the geometric models of the cylinders and the cylindrical tube components to obtain the geometric model of the irregularly cracked cylindrical tube, as shown below. Figure 8 As shown.

[0078] Step 5: Set the control size of the perfect zone to 15mm, generate the finite element mesh for the perfect zone, and then freely generate the finite element mesh for the cracked zone to obtain the finite element analysis model of the overall structure of the cracked circular tube. Figure 9 As shown.

Claims

1. A method for modeling irregular cracks in a finite element analysis model of a steel structure component, characterized by: Includes the following steps: Step (1) Establish a global coordinate system O-XYZ based on the shape of the steel structure component, establish a geometric model of the component based on the geometric dimensions of the component, generate irregular cracks randomly or according to the planned path, establish a virtual plane rectangular coordinate system xoy with the center of the crack area of ​​the irregular crack as the origin of the coordinate system, and the x and y axes are consistent with the X and Y axes respectively. Take any quadrant of the coordinate system xoy as the crack start position. Step (2) construct irregular cracks in the geometric model of the component by a series of overlapping cylinders, randomly determine the radius of each cylinder and the distance between the centers of two adjacent cylinders according to the crack width, and then randomly determine the relative orientation between two adjacent cylinders. Step (3) Create all cylinders in the crack zone, and perform Boolean operations between all these cylinders and the crack zone to construct a geometric model of the component with irregular cracks; Step (4) On the geometric model of the component with irregular cracks, for the perfect area outside the crack zone, the finite element mesh of the perfect area is divided by mapping, and the finite element mesh of the crack zone is divided by free method to obtain the finite element analysis model of the component with irregular cracks, and the modeling is completed. The position of the first cylinder is determined based on the crack initiation position. The radii of the first and second cylinders are randomly generated within the crack width range. Starting from the center of the first cylinder, a center-to-center distance and azimuth angle are randomly generated to determine the center position of the second cylinder. Then, the third cylinder is generated starting from the second cylinder, and so on, to generate a series of overlapping cylinders. Define a two-dimensional array CK(N,4) to record the center coordinates and radius of each cylinder in the global coordinate system O-XYZ. Each row of data in the two-dimensional array CK(N,4) corresponds to the coordinates (X, Y, Z) and radius (R) of cylinder i generated when a crack is constructed, where i∈n, n is the total number of cylinders, n≤N, and N is the length of the two-dimensional array. When satisfied The generation of cylinders stops when the time is right; LCK is the crack length, d i The distance between the centers of two adjacent cylinders; The minimum distance between the centers of two adjacent cylinders is 0.5*CK. L CK L The lower limit of the crack width range is given by the two-dimensional array length N = 2*LCK / CK. L .

2. The method for modeling irregular cracks in the finite element analysis model of steel structure components according to claim 1, characterized in that: in Crack width range [0.5*CK] L 0.5*CK U The radius of the cylinder is randomly generated within ] , CK L CK is the lower limit of the crack width range. U This represents the upper limit of the crack width range.

3. The method for modeling irregular cracks in the finite element analysis model of steel structure components according to claim 1, characterized in that: Comparing the radius of the second cylinder with the radius of the first cylinder, we obtain the smaller radius R. L and larger radius R U In the radius interval [R] L R U A random number is generated within the range and used as the center distance d1 between the two overlapping cylinders.

4. The method for modeling irregular cracks in the finite element analysis model of steel structure components according to claim 3, characterized in that: in The set azimuth interval [α] L , α U A random azimuth angle α1 is generated. Taking the center of the first cylinder as the starting point, the position of the second cylinder is determined based on the center distance d1 and the azimuth angle α1.

5. The method for modeling irregular cracks in the finite element analysis model of steel structure components according to claim 4, characterized in that: the second... The position coordinates of the cylinder are calculated as follows: X = CK[1][1] + d1 * COSα1, Y = CK[1][2] + d1 * SINα1.

6. The method for modeling irregular cracks in the finite element analysis model of steel structure components according to claim 4, characterized in that: Determine whether the second cylinder is within the crack zone. If the generated second cylinder is close to the boundary of the crack zone, then randomly generate an azimuth angle α1 again to make it fall into the crack zone.

7. The method for modeling irregular cracks in the finite element analysis model of steel structure components according to claim 6, characterized in that: Set a distance threshold to control the distance between the crack and the crack zone boundary to be no less than the set distance threshold.

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