A method for establishing a roulette wheel partitioning model based on stress distribution

Abstract

This invention relates to a method for establishing a wheel disk partitioning model based on stress distribution, which improves the calculation efficiency of crack propagation at different locations on the wheel disk, thereby enabling failure risk assessment based on wheel disk stress partitioning. Specifically, it employs finite element parametric modeling, extracting the principal stress orthogonal plane as the crack propagation plane, which can include all stress components in the calculation range and consider the influence of asymmetric processing features. Based on a coordinate system transformation method, the three-dimensional coordinates of points on the principal stress orthogonal plane are transformed into two-dimensional coordinates, reducing dimensionality and simplifying the calculation steps. The method for establishing a wheel disk partitioning model based on stress distribution established in this invention directly achieves rapid automatic partitioning based on stress and location, significantly improving efficiency. Simultaneously, it classifies regions into internal regions, surface regions, and corner regions to consider the differences in crack risk at different locations on the wheel disk. The final partitioning result is consistent with the calculation examples provided by the FAA airworthiness advisory circular.

Description

Technical Field

[0001] This invention relates to the field of probabilistic damage tolerance assessment technology for aero-engines, and specifically to a method for establishing a wheel partition model based on stress distribution. Background Technology

[0002] Life-limited components in aero-engines refer to rotors and major stator structural components whose primary failure could jeopardize engine safety. Even a minor defect in a life-limited component can severely threaten its safety. Therefore, the US aerospace industry has proposed an enhanced life-cycle management process to ensure the safety of life-limited components. The core of this process is to consider extremely low-probability defects and conduct probabilistic damage tolerance assessments. This assessment method combines random factors such as defects, loads, and non-destructive testing to calculate the failure risk of aero-engine life-limited components and measure the safety of their design.

[0003] Taking a roulette wheel as an example, since the initial defect size and its location within the wheel are random, a zoning study based on the wheel's stress distribution is necessary. The core of this study involves performing stress analysis on the wheel using finite element method (FEM) software, then establishing a zoning algorithm based on certain zoning criteria to obtain stress and zoning characteristics, thereby conducting a failure risk assessment based on wheel zoning. Therefore, a method for establishing a wheel stress zoning model needs to be developed: based on finite element calculation results, a stress zoning algorithm is developed to divide the wheel into multiple regions with similar risks in the principal stress orthogonal plane, and finally, a failure risk assessment is performed.

[0004] The latest partitioning method abroad is an automatic partitioning method based on pre-partitioning. This method pre-partitions finite element data with similar characteristics such as stress and temperature, including calculating risk surfaces, determining risk limit locations, and executing automatic partitioning algorithms. Its main computational cost lies in the risk assessment of training points. Summary of the Invention

[0005] In view of the above problems, this invention provides a method for establishing a wheel disk partitioning model based on stress distribution. This invention employs finite element parametric modeling, extracting the principal stress orthogonal plane as the crack propagation plane, incorporating all stress components into the calculation range, and considering the influence of asymmetric processing features. Based on a coordinate system transformation method, the three-dimensional coordinates of points on the principal stress orthogonal plane are converted into two-dimensional coordinates, reducing dimensionality and simplifying the calculation steps. This invention directly achieves rapid automatic partitioning based on stress and location, significantly improving efficiency. It classifies regions into internal regions, surface regions, and corner regions. Based on stress similarity, surface region refinement, and geometric continuity judgment, it can efficiently and accurately evaluate the partitioning results for probabilistic damage tolerance of life-limited components. This invention considers the difference in crack risk at different locations on the wheel disk, and the final partitioning results are consistent with the calculation examples provided by the FAA airworthiness advisory circular. This invention provides technical support for the probabilistic damage tolerance assessment of aero-engine wheel disks and has significant engineering significance and practical value.

[0006] This invention provides a method for establishing a roulette wheel partition model based on stress distribution, comprising:

[0007] Step S1: Establish a finite element model of the roulette wheel structure; apply periodic external forces to the finite element model of the roulette wheel structure.

[0008] Step S2: Determine the fatigue crack initiation location and principal stress orthogonal plane direction of the wheel structure, and extract the crack propagation plane to characterize the principal stress orthogonal plane;

[0009] Obtain the three-dimensional coordinates of each node in the principal stress orthogonal plane and the stress value of each node;

[0010] Step S3: Reduce the dimensionality of the three-dimensional coordinates of each node in the principal stress orthogonal plane to obtain the two-dimensional coordinates of each node;

[0011] Step S4: Divide the principal stress orthogonal plane after dimensionality reduction into elements. Each element includes multiple nodes, two-dimensional coordinates of each node, the correspondence between each node, and the stress value of each node.

[0012] Step S5: Identify the unit type of each unit;

[0013] Step S6: Obtain the maximum stress value of each element, and obtain the maximum stress value of the principal stress orthogonal plane based on the maximum stress value of each element;

[0014] The stress value range of the principal stress orthogonal plane is set based on the maximum stress value of the principal stress orthogonal plane;

[0015] Step S7: Set the stress gradient and perform the first stress partitioning of the stress value range according to the stress gradient;

[0016] Step S8: According to the element type, perform a second stress partitioning on the stress interval after the first stress partitioning to obtain multiple stress partitions;

[0017] Step S9: Let n = 1. When n = 1, it represents the first stress zone.

[0018] Step S10: Process each element in the nth stress partition based on the principle of geometric continuity, determine whether there are geometrically discontinuous elements in the corresponding stress partition, if so, create the (n+1)th stress partition based on the geometrically discontinuous elements, let n = n+1, update the total number of stress intervals N, and return to step S9.

[0019] If not, obtain the nth updated stress partition, record it, and proceed to the next step;

[0020] Step S11: Repeat steps S9-S10 to traverse each stress zone and obtain multiple updated stress zones. Based on the multiple updated stress zones, establish a disk structure partition model.

[0021] Preferably, the specific steps for obtaining the three-dimensional coordinates of each node in the principal stress orthogonal plane in step S2 include:

[0022] Obtain multiple intersection points between the principal stress orthogonal plane and the finite element model of the wheel structure;

[0023] Each intersection point is represented as a node in the principal stress orthogonal plane, and the three-dimensional coordinates of each node are obtained. The principal stress value of each node is obtained by linear interpolation.

[0024] Preferably, the specific steps for obtaining the three-dimensional coordinates of each node and the principal stress values ​​of each node include:

[0025] The stress maximum point of the finite element model of the wheel structure after the application of external force was obtained using the finite element software ABAQUS.

[0026] The point of maximum stress is set as the fatigue crack initiation location, and the direction of the principal stress orthogonal plane is determined; the principal stress values ​​of the wheel structure are obtained based on the third-order stress state equation of elasticity and the fatigue crack initiation location;

[0027] Based on the fatigue crack initiation location and the direction of the principal stress orthogonal plane, the principal stress orthogonal plane is extracted; the principal stress orthogonal plane is characterized as the crack propagation plane.

[0028] Determine whether any two adjacent nodes in the finite element model of the wheel structure intersect with the principal stress orthogonal plane, and obtain multiple intersection points between the principal stress orthogonal plane and the finite element model of the wheel structure;

[0029] Each intersection point is represented as a node in the principal stress orthogonal plane, and the three-dimensional coordinates of each node are obtained.

[0030] The stress value of each node is calculated by linear interpolation.

[0031] Preferably, the principal stress orthogonal plane includes boundary nodes, and the number of elements connected by the boundary nodes is 1 and / or 2 / 3.

[0032] Preferably, the unit type in step S5 is an internal unit, a corner unit, or a surface unit.

[0033] Preferably, the specific steps for identifying the unit type of each unit include:

[0034] Obtain the correspondence between nodes in each element and the boundary nodes. Determine whether the number of boundary nodes in each element is greater than 1. If yes, the corresponding element is a surface element; otherwise, the corresponding element is an internal element.

[0035] Calculate the number of elements in a surface element or internal element where each node is shared;

[0036] Determine if the number of shared units for each node is equal to 1. If yes, the corresponding node is a corner node and proceed to the next step. If no, proceed to the next step.

[0037] Determine whether each element contains a corner node. If it does, then the corresponding element is determined to be a corner element; otherwise, the original element type is retained.

[0038] Preferably, the first stress partitioning in step S7 involves assigning nodes with similar stress values ​​to corresponding stress partitions.

[0039] Preferably, the specific steps for performing the second stress zoning include:

[0040] Each stress zone is divided into near-surface zones according to the element type, resulting in multiple internal stress zones and multiple surface stress zones.

[0041] After near-surface partitioning, the remaining elements are partitioned into corner elements to obtain multiple corner element stress partitions.

[0042] Preferably, the specific steps for obtaining the nth updated stress partition in step S10 include:

[0043] Step S10-1: Select the nth stress zone;

[0044] Step S10-2: Determine whether the number of elements in the nth stress zone is 1. If so, it indicates that the stress zone is a geometrically continuous stress zone, and record it.

[0045] If not, then label all elements in the nth stress partition as "remainder" and select any element as "source".

[0046] Step S10-3: Find all neighboring cells of the source cell among multiple redundant cells, and name all neighboring cells as the neighboring source cell set;

[0047] Step S10-4: Repeat step S10-3, traverse all remaining elements in the nth stress partition until no new elements can be found, determine whether there are any remaining elements in the corresponding stress partition that participate in the geometric continuity judgment. If there are, it means that there are remaining elements in the stress partition that are not adjacent to multiple geometric continuous elements. Create a new partition based on the remaining elements to obtain the (n+1)th stress partition. Let n = n+1 and return to step S10-1.

[0048] If not, it means that the corresponding stress partition has geometric continuity, and the nth updated stress partition is obtained;

[0049] Step S10-5: Traverse each stress partition, repeating steps S10-1 and S10-4 to obtain multiple updated stress partitions.

[0050] Preferably, the total number of partitions n obtained after the second stress partitioning is... zone The expression is:

[0051] n zone =2n stress +n corner

[0052] Where, n corner The number of angular units, n stress Indicates the number of stress intervals.

[0053] The present invention also includes: step 12, assessing the failure risk of the wheel based on the wheel stress zoning model.

[0054] (1) The model of this invention is based on the principal stress orthogonal plane, which includes all stress components in the calculation range and takes into account the influence of asymmetric processing characteristics.

[0055] (2) This invention reduces the computational dimension and simplifies the steps by transforming the three-dimensional coordinates of points on the principal stress orthogonal plane into two-dimensional coordinates;

[0056] (3) The present invention achieves rapid automatic partitioning based on stress and position, which has relatively higher calculation efficiency and lower calculation cost. Attached Figure Description

[0057] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0058] Figure 1 This is a schematic diagram of the boundary recognition and unit classification process in an embodiment of the present invention;

[0059] Figure 2 This is a schematic diagram of the flow of the wheel stress partitioning algorithm in an embodiment of the present invention;

[0060] Figure 3 This is a schematic diagram of the stress zoning process in an embodiment of the present invention;

[0061] Figure 4 This is a schematic diagram of the corner unit, internal unit, and surface unit in an embodiment of the present invention;

[0062] Figure 5 This is a schematic diagram of the disk stress zoning results in an embodiment of the present invention. Detailed Implementation

[0063] To better understand the above-described objectives, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Furthermore, the present invention can be implemented in other ways different from those described herein; therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0064] A specific embodiment of the present invention, such as Figure 1-5 This invention discloses a method for establishing a roulette wheel partitioning model based on stress distribution. To illustrate the effectiveness of the proposed method, a specific embodiment is provided below for detailed explanation of the above-mentioned technical solution. The specific implementation steps are as follows:

[0065] This invention provides a method for establishing a roulette wheel partition model based on stress distribution, comprising:

[0066] Step S1: Establish a finite element model of the wheel structure, and set the material parameters, boundary conditions, and load conditions of the finite element model of the wheel structure;

[0067] Periodic external forces are applied to the finite element model of the roulette structure;

[0068] Preferably, the material parameters in step S1 include elastic modulus, Poisson's ratio, yield strength, ultimate strength, and density;

[0069] A periodic symmetrical external force is applied to the wheel structure using a master-slave surface setting method;

[0070] The boundary conditions include the configuration of the master face, slave face, and rotation axis of the wheel structure, as well as the number of applied cycles; simultaneously, axial and circumferential constraints are applied to the flange face.

[0071] The load conditions include the wheel rotation speed and the applied load;

[0072] Step S2: Obtain the fatigue crack initiation location and principal stress orthogonal plane direction of the wheel structure based on the finite element model of the wheel structure; extract the crack propagation plane based on the fatigue crack initiation location and principal stress orthogonal plane direction, and characterize it as the principal stress orthogonal plane;

[0073] Obtain multiple intersection points between the principal stress orthogonal plane and the finite element model of the wheel structure;

[0074] Each intersection point is represented as a node in the principal stress orthogonal plane, and the three-dimensional coordinates of each node are obtained; the principal stress values ​​of each node are obtained by linear interpolation.

[0075] Furthermore, the specific steps for obtaining the principal stress values ​​of each node through linear interpolation include:

[0076] The stress maximum point of the finite element model of the wheel structure after the application of external force was obtained using the finite element software ABAQUS.

[0077] The point of maximum stress is set as the fatigue crack initiation location, and the direction of the principal stress orthogonal plane is determined; the principal stress values ​​of the wheel structure are obtained based on the third-order stress state equation of elasticity and the fatigue crack initiation location;

[0078] Based on the fatigue crack initiation location and the direction of the principal stress orthogonal plane, the principal stress orthogonal plane is extracted; the principal stress orthogonal plane is characterized as the crack propagation plane.

[0079] Determine whether any two adjacent nodes in the finite element model of the wheel structure intersect with the principal stress orthogonal plane, and obtain multiple intersection points between the principal stress orthogonal plane and the finite element model of the wheel structure;

[0080] Each intersection point is represented as a node in the principal stress orthogonal plane, and the three-dimensional coordinates of each node are obtained.

[0081] The stress value of each node is calculated by linear interpolation;

[0082] Furthermore, the expression for the third-order stress state equation in elasticity is as follows:

[0083]

[0084] Where σ1 is the first principal stress or the maximum principal stress, σ2 is the second principal stress, and σ3 is the third principal stress; I1 is the first invariant of the stress tensor, I2 is the second invariant of the stress tensor, and I3 is the third invariant of the stress tensor; σ xx σ represents the normal stress acting in the x-direction. yyσ represents the normal stress acting in the y-direction. zz σ represents the normal stress acting in the z-direction. xy σ represents the stress acting in the y direction on the x-plane. xz σ represents the stress acting in the z-direction on the x-plane. yz This represents the stress acting in the z direction on the y-plane.

[0085] Furthermore, the equation for the direction of the maximum principal stress is expressed as follows:

[0086]

[0087] lσ xz +mσ yz +n(σ zz -σ1)=0

[0088] l 2 +m 2 +n 2 =1

[0089] Where l represents the x-direction component of the maximum principal stress, m represents the y-direction component of the maximum principal stress, and n represents the z-direction component of the maximum principal stress.

[0090] The expression for the orthogonal plane of principal stresses:

[0091] l(x-a)+m(y-b)+n(z-c)=0 (3)

[0092] Where a represents the x-axis coordinate of the point of maximum principal stress, b represents the y-axis coordinate of the point of maximum principal stress, z represents the z-axis coordinate of the node, c represents the z-axis coordinate of the point of maximum principal stress, and (x, y, z) represents the coordinates of the node on the principal stress orthogonal plane, where x represents the x-axis coordinate of the node, y represents the y-axis coordinate of the node, and z represents the z-axis coordinate of the node.

[0093] For example, the expressions for the relationship points between the i-th and j-th adjacent nodes of the finite element model of the wheel structure and the principal stress orthogonal plane are as follows:

[0094]

[0095] Among them, s i Let s be the relationship point between the i-th node of the finite element model of the wheel structure and the principal stress orthogonal plane. j Let x be the relationship point between the j-th node of the finite element model of the roulette structure and the principal stress orthogonal plane. i The x-axis coordinate and y-axis coordinate of the i-th node in the finite element model of the roulette structure are represented by the given coordinates. iLet x represent the y-axis coordinate of the i-th node in the finite element model of the roulette structure, z represent the z-axis coordinate of the i-th node in the finite element model of the roulette structure, and x represent the y-axis coordinate of the i-th node in the finite element model of the roulette structure. j The x-axis coordinate of the j-th node in the finite element model of the roulette structure is represented by the y-axis coordinate. j The z-axis coordinate of the j-th node in the finite element model of the roulette structure is represented by z. j This represents the z-axis coordinate of the j-th node.

[0096] Furthermore, the specific steps to obtain multiple intersection points include:

[0097] The relationship between the two adjacent nodes and the principal stress orthogonal plane in the finite element model of the wheel structure is obtained from point s. i Relationship point two s j ;

[0098] Define the criteria for determining intersection points;

[0099] If s i ×s j If the value is less than 0, then the two adjacent nodes are located on opposite sides of the principal stress orthogonal plane, and the line segment formed by these two nodes intersects the principal stress orthogonal plane.

[0100] If s i ×s j If the value is greater than 0, then the two adjacent nodes are located on the same side of the principal stress orthogonal plane, and the line segment formed by these two nodes has no intersection with the principal stress orthogonal plane.

[0101] If s i ×s j =0, then one of the two adjacent nodes lies on the principal stress orthogonal plane; substitute all the nodes of the finite element model of the wheel structure into the principal stress orthogonal plane equation to find the intersection point on the principal stress orthogonal plane.

[0102] Furthermore, it also includes obtaining the total stress value at each intersection point, with specific steps including:

[0103] Obtain the relationship points between the i-th and j-th adjacent nodes of the finite element model of the wheel structure and the principal stress orthogonal plane, respectively;

[0104] Based on the relationship points between the i-th section and j-th node of the finite element model of the roulette structure and the principal stress orthogonal plane, the linear equations of adjacent i-th sections and j-th nodes are established. Based on these linear equations, the intersection point (x) is obtained. ij ,y ij ,z ij );

[0105] The intersection point (x) is calculated using linear interpolation. ij ,y ij ,zij The three-dimensional stress components are obtained; the principal stress values ​​at the intersection points are obtained based on the three-dimensional stress components.

[0106] Furthermore, the specific steps for obtaining the principal stress values ​​at each intersection point include:

[0107] Taking two nodes on a plane defined by the z-coordinate as an example, the equation of the line between two adjacent nodes is expressed as:

[0108] (y j -y i (xx) i )+(y i -y)(x j -x i )=0 (5)

[0109] The intersection point (x) ij ,y ij ,z ij The three-dimensional stress value expression is:

[0110]

[0111] Where, σ xxij The intersection point (x) ij ,y ij ,z ij Stress along the x-axis; σ xxj σ represents the stress at node j along the x-axis; xxi Let x be the stress at node i along the x-axis; ij The x-axis coordinate represents the intersection point of node i and node j.

[0112] The principal stress value σ N The expression is:

[0113] σ N =l 2 σ xx +m 2 σ yy +n 2 σ zz +2(mnσ yz +nlσ xz +lmσ xy (7)

[0114] Where, σ xx σ represents the stress at adjacent nodes along the x-axis. yy σ represents the stress at adjacent nodes along the y-axis. zz σ represents the stress at adjacent nodes along the z-axis. yz Let σ be the stress acting in the y direction on the x-plane. xz Let σ be the stress acting in the z direction on the x-plane. xyLet be the stress acting in the z direction on the y-plane.

[0115] Step S3: Reduce the dimensionality of the three-dimensional coordinates of each node in the principal stress orthogonal plane to obtain the two-dimensional coordinates of each node;

[0116] Preferably, obtaining the two-dimensional coordinates of each node specifically includes:

[0117] Select coordinate axes Vector x and Vector y that are perpendicular to each other on the principal stress orthogonal plane, and Vector z that is the normal vector of the principal stress orthogonal plane, and construct a two-dimensional coordinate system;

[0118] Establish a coordinate transformation matrix T based on the aforementioned two-dimensional coordinate system;

[0119] Invert the coordinate transformation matrix T to obtain the inverted coordinate matrix; use the inverted coordinate matrix to obtain the two-dimensional coordinates of each node;

[0120] Furthermore, the expression for the coordinate transformation matrix T is:

[0121]

[0122] Among them, W x W represents the variable in the x-direction of the coordinate vector z. y W represents the variable in the y-direction of the coordinate vector z. z A variable representing the z-direction of the coordinate vector z;

[0123] U x The variable U represents the x-direction of the coordinate vector x. y U represents the variable in the y-direction of the coordinate vector x. z A variable representing the z-direction of the coordinate vector x;

[0124] V x V represents the variable in the x-direction of the coordinate vector y. y V represents the variable in the y-direction of the coordinate vector y. z The variable representing the z-direction of the coordinate axis Vector y; Vector z = (W x W y W z ) represents the direction cosine of the normal vector on the plane orthogonal to the principal stresses, as mentioned earlier, i.e., Vector z = (W x W y W z )=(l,m,n); and Vector x=(U x Uy U z Vector y = (V x V y V z One way to determine the direction vector on the two principal stress orthogonal planes is as follows: The nodal coordinates of the principal stress orthogonal planes are known. Take one of the points (x0, y0, z0) as the origin of the new coordinate system, and then take another point (x1, y1, z1). Take (x1-x0, y1-y0, z1-z0) as the x-axis direction vector in the new coordinate system, i.e., Vector x.

[0125] For the direction vector Vector y, since the three vectors are perpendicular to each other, its determination can be expressed as follows:

[0126] Vector y=Vector x×Vector z=(x1-x0,y1-y0,z1-z0)×(l,m,n) (9)

[0127] Step S4: Divide the principal stress orthogonal plane after dimensionality reduction into elements. Each element includes multiple nodes, two-dimensional coordinates of each node, the correspondence between each node, and the stress value of each node.

[0128] Optionally, the principal stress orthogonal plane includes boundary nodes, and the number of elements connected by the boundary nodes is 1 and / or 2 / 3.

[0129] It is understandable that the node N i The two-dimensional coordinates are (x Ni ,y Ni );

[0130] Each unit includes: the stress temperature of the node is node N. i Principal stress value s Ni and temperature T Ni ;

[0131] The correspondence between the unit nodes is f(N) i,1 N i,2 N i,3 N i,4 ) = E r E r The unit r represents four nodes N. i,1 N i,2 N i,3 N i,4 ;

[0132] Each node N in the unit i Nodes are categorized by location as corner nodes, surface nodes, or internal nodes, and each node connects to n units.i The values ​​are 1, 2 / 3, and 4, and their expressions are g1(E) respectively. i,1 ) = N i ,g1(E i,1 g2(E) indicates that a cell node connects to a cell; i,1 E i,2 ) = N i g2(E i,1 E i,2 ) indicates that the element node connects two elements; g3(E i,1 E i,2 E i,3 ) = N i g3(E i,1 E i,2 E i,3 ) indicates that the element node connection consists of three elements; g4(E i,1 E i,2 E i,3 E i,4 ) = N i g4(E i,1 E i,2 E i,3 E i,4 A node represents a node that connects four elements. When a node connects to 1 or / or 2 / 3 elements, it is a boundary node.

[0133] It is understood that the coordinates of the boundary nodes are the set of coordinates of all discrete boundary nodes in the roulette wheel partitioning model, L = {(x,y)|(x1,y1),...,(x...y1)}. p ,y p ),...,(x q ,y q )}(2≤p≤q), where q represents the number of boundary nodes.

[0134] Preferably, the unit includes unit centroid coordinates (x... E ,y E ), unit volume V E , element stress σ E Unit temperature T E ;

[0135] Furthermore, the unit centroid coordinates (x E ,y E ), unit volume V E , element stress σ E Unit temperature T E The expressions are as follows:

[0136]

[0137] Where, x Ni Represents the x-axis coordinate of node i on the element, y-axis coordinate of node i on the element. Ni σ represents the y-coordinate of node i in the element. i T represents the stress at node i on the element. i x represents the temperature at node i on the element. max This represents the maximum x-axis coordinate of node i in the element. min This represents the maximum x-axis coordinate of node i in the element, and y-axis coordinate of node i. max This represents the maximum y-axis coordinate of node i in the element. min This represents the minimum y-axis coordinate of node i in the unit.

[0138] Preferably, the unit classification includes internal units, surface units, and corner units, denoted by t(E). j ) = 1, t(E j ) = 2 and t(E j ) = 3 indicates the cell type. Iterate through each cell E. j The number of boundary nodes among the four nodes of an element is used to distinguish between internal and surface elements; if an element contains at least one corner node, then that element is defined as a corner element. Specifically:

[0139] Preferably, the unit classification includes internal units, surface units, and corner units, traversing each unit E j The number of boundary nodes among the four nodes of an element is used to distinguish between internal and surface elements; if an element contains at least one corner node, then that element is defined as a corner element. Specifically:

[0140] For each unit E r and the set N of its four corresponding nodes Er ,have:

[0141]

[0142] Where N represents any node, N Er It is unit E r Let A be the set of nodes, and B be the set of surface nodes.

[0143] Step S5: Identify the unit type of each unit;

[0144] Preferably, the specific steps for identifying the unit type of each unit include:

[0145] Obtain the correspondence between nodes in each element and the boundary nodes. Determine whether the number of boundary nodes in each element is greater than 1. If yes, the corresponding element is a surface element; otherwise, the corresponding element is an internal element.

[0146] Calculate the number of elements in a surface element or internal element where each node is shared;

[0147] Determine if the number of shared units for each node is equal to 1. If yes, the corresponding node is a corner node and proceed to the next step. If no, proceed to the next step.

[0148] Determine whether each element contains a corner node. If it does, then the corresponding element is determined to be a corner element; otherwise, the original element type is retained.

[0149] Step S6: Obtain the maximum stress value of each element, and obtain the maximum stress value of the principal stress orthogonal plane based on the maximum stress value of each element;

[0150] The stress value range of the principal stress orthogonal plane is set based on the maximum stress value of the principal stress orthogonal plane;

[0151] Step S7: Set the stress gradient and perform the first stress partitioning of the stress value range according to the stress gradient; the first stress partitioning is to divide nodes with similar stress values ​​into the corresponding stress partitions.

[0152] Preferably, the expression for the number of stress intervals is:

[0153]

[0154] Where, n stress This indicates the number of stress intervals, and Δσ represents the width of a single stress interval. Indicates rounding up, σ max σ represents the maximum stress value. min This represents the minimum stress value.

[0155] Step S8: According to the element type, perform a second stress partitioning on the stress interval after the first stress partitioning to obtain multiple stress partitions;

[0156] The stress partitioning includes internal stress partitioning, surface stress partitioning, and corner element stress partitioning;

[0157] Preferably, the total number of partitions n obtained after the second stress partitioning is... zone The expression is:

[0158] n zone =2n stress +n corner (13)

[0159] Where, n corner Indicates the number of angular units.

[0160] Preferably, the specific steps for performing the second stress zoning include:

[0161] Each stress zone is divided into near-surface zones according to the element type, resulting in multiple internal stress zones and multiple surface stress zones.

[0162] After near-surface partitioning, the remaining elements are partitioned into corner elements to obtain multiple corner element stress partitions;

[0163] Step S9: Let n = 1. When n = 1, it represents the first stress zone.

[0164] Step S10: Process each element in the nth stress partition based on the principle of geometric continuity, determine whether there are geometrically discontinuous elements in the corresponding stress partition, if so, create the (n+1)th stress partition based on the geometrically discontinuous elements, let n = n+1, update the total number of stress intervals N, and return to step S9.

[0165] If not, obtain the nth updated stress partition, record it, and proceed to the next step; specifically, step S10, processing each element in the nth stress partition based on the geometric continuity principle to obtain the nth updated stress partition, includes the following steps:

[0166] Step S10-1: Select the nth stress zone;

[0167] Step S10-2: Determine whether the number of elements in the nth stress zone is 1. If so, it indicates that the stress zone is a geometrically continuous stress zone, and record it.

[0168] If not, then label all elements in the nth stress partition as "remainder" and select any element as "source".

[0169] Step S10-3: Find the source element (Source) among multiple co-cells left0. s All adjacent cells, and name all adjacent cells as the neighboring source cell set. s+1 ;

[0170] Step S10-4: Repeat step S10-3, traverse all remaining elements in the nth stress partition until no new elements can be found, determine whether there are any remaining elements in the corresponding stress partition that participate in the geometric continuity judgment. If there are, it means that there are remaining elements in the stress partition that are not adjacent to multiple geometric continuous elements. Create a new partition based on the remaining elements to obtain the (n+1)th stress partition. Let n = n+1 and return to step S10-1.

[0171] If not, it means that the corresponding stress partition has geometric continuity, and the nth updated stress partition is obtained;

[0172] Step S10-5: Traverse each stress partition, repeating steps S10-1 and S10-4 to obtain multiple updated stress partitions.

[0173] Step S11: Repeat steps S9-S10 to traverse each stress zone and obtain multiple updated stress zones. Based on the multiple updated stress zones, establish a disk structure partition model.

[0174] For example, the specific steps of the unit adjacency criterion include: taking any two units E1 and E2 as an example, where the set of nodes corresponding to E1 can be represented as A1 = {N}. 1,1 N 1,2 N 1,3 N 1,4 The set of nodes corresponding to E2 can be represented as A2 = {N}. 2,1 N 2,2 N 2,3 N 2,4 Let B = A1∪A2. If |B| = 6, then units E1 and E2 have 2 shared nodes and are adjacent units; if |B| = 7, then units E1 and E2 have 1 shared node and are diagonal units rather than adjacent units; if |B| = 8, then units E1 and E2 have no shared nodes and are neither diagonal units nor adjacent units.

[0175] The present invention also includes: step 12, assessing the failure risk of the wheel based on the wheel stress zoning model.

[0176] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for establishing a roulette wheel partition model based on stress distribution, characterized in that, include: Step S1: Establish the finite element model of the wheel structure; Periodic external forces are applied to the finite element model of the roulette structure; Step S2: Determine the fatigue crack initiation location and principal stress orthogonal plane direction of the wheel structure, and extract the crack propagation plane to characterize the principal stress orthogonal plane; Obtain the three-dimensional coordinates of each node in the principal stress orthogonal plane and the principal stress values ​​of each node; Step S3: Reduce the dimensionality of the three-dimensional coordinates of each node in the principal stress orthogonal plane to obtain the two-dimensional coordinates of each node; Step S4: Divide the principal stress orthogonal plane after dimensionality reduction into elements. Each element includes multiple nodes, two-dimensional coordinates of each node, the correspondence between each node, and the stress value of each node. Step S5: Identify the unit type of each unit. Specific steps include: Obtain the correspondence between nodes in each element and the boundary nodes. Determine whether the number of boundary nodes in each element is greater than 1. If yes, the corresponding element is a surface element; otherwise, the corresponding element is an internal element. Calculate the number of elements in a surface element or internal element where each node is shared; Determine if the number of shared units for each node is equal to 1. If yes, the corresponding node is a corner node and proceed to the next step. If no, proceed to the next step. Determine whether each element contains a corner node. If it does, then the corresponding element is determined to be a corner element; otherwise, the original element type is retained. Step S6: Obtain the maximum stress value of each element, and obtain the maximum stress value of the principal stress orthogonal plane based on the maximum stress value of each element; The stress value range of the principal stress orthogonal plane is set based on the maximum stress value of the principal stress orthogonal plane; Step S7: Set the stress gradient and perform the first stress partitioning of the stress value range according to the stress gradient; the first stress partitioning is to divide nodes with similar stress values ​​into the corresponding stress partitions. Step S8: According to the element type, perform a second stress partitioning on the stress intervals after the first stress partitioning to obtain multiple stress partitions. The specific steps include: Each stress zone is divided into near-surface zones according to the element type, resulting in multiple internal stress zones and multiple surface stress zones. After near-surface partitioning, the remaining elements are partitioned into corner elements to obtain multiple corner element stress partitions; Step S9, let n =1, when n When =1, it indicates the first stress zone; Step S10: Based on the principle of geometric continuity, the first... n Each element in the stress partition is processed to determine whether the corresponding stress partition contains geometrically discontinuous elements. If so, a first stress partition is created based on the geometrically discontinuous elements. n +1 stress zone, let n = n +1, and update the total number of stress intervals. N Return to step S9; If not, obtain the first n Update the stress partition, record it, and proceed to the next step; Step S11: Repeat steps S9-S10 to traverse each stress zone and obtain multiple updated stress zones. Based on the multiple updated stress zones, establish a disk structure partition model.

2. The method for establishing a roulette wheel partition model based on stress distribution according to claim 1, characterized in that, The specific steps for obtaining the three-dimensional coordinates of each node in the principal stress orthogonal plane as described in step S2 include: Obtain multiple intersection points between the principal stress orthogonal plane and the finite element model of the wheel structure; Each intersection point is represented as a node in the principal stress orthogonal plane, and the three-dimensional coordinates of each node are obtained; the principal stress values ​​of each node are obtained by linear interpolation.

3. The method for establishing a roulette wheel partition model based on stress distribution according to claim 2, characterized in that, The specific steps to obtain the 3D coordinates of each node include: The stress maximum point of the finite element model of the wheel structure after the application of external force was obtained using the finite element software ABAQUS. The point of maximum stress is set as the fatigue crack initiation location, and the direction of the principal stress orthogonal plane is determined; the principal stress values ​​of the wheel structure are obtained based on the third-order stress state equation of elasticity and the fatigue crack initiation location; Based on the fatigue crack initiation location and the direction of the principal stress orthogonal plane, the principal stress orthogonal plane is extracted; the principal stress orthogonal plane is characterized as the crack propagation plane. Determine whether any two adjacent nodes in the finite element model of the wheel structure intersect with the principal stress orthogonal plane, and obtain multiple intersection points between the principal stress orthogonal plane and the finite element model of the wheel structure; Each intersection point is represented as a node in the principal stress orthogonal plane, and the three-dimensional coordinates of each node are obtained. The stress value of each node is calculated by linear interpolation.

4. The method for establishing a roulette wheel partition model based on stress distribution according to claim 2, characterized in that, The principal stress orthogonal plane includes boundary nodes, and the number of elements connected by the boundary nodes is 1, 2 and / or 3.

5. The method for establishing a roulette wheel partition model based on stress distribution according to claim 1, characterized in that, The unit types mentioned in step S5 are internal units, corner units, and surface units.

6. The method for establishing a roulette wheel partition model based on stress distribution according to claim 1, characterized in that, Step S10 describes obtaining the first n The specific steps for updating stress zones include: Step S10-1: Select the first n One stress zone; Step S10-2, determine the first n If the number of elements in a stress partition is 1, then the stress partition is a geometrically continuous stress partition, and this is recorded. If not, then the first n All elements in a stress partition are labeled as "excess," and any element is selected and labeled as "source." Step S10-3: Find all neighboring cells of the source cell among multiple redundant cells, and name all neighboring cells as the neighboring source cell set; Step S10-4: Repeat step S10-3, traversing the... n In each stress partition, all remaining elements are considered until no new elements can be found. It is then determined whether any elements in the corresponding stress partition are still involved in the geometric continuity assessment. If so, it indicates that there are remaining elements in that stress partition that are not adjacent to multiple geometrically continuous elements. A new partition is then created based on these remaining elements, resulting in the [number missing]th stress partition. n +1 stress zone, let n = n +1, return to step S10-1; If not, it indicates that the corresponding stress partition has geometric continuity, thus obtaining the first... n One updated stress partition; Step S10-5: Traverse each stress partition, repeating steps S10-1 and S10-4 to obtain multiple updated stress partitions.

7. The method for establishing a roulette wheel partition model based on stress distribution according to claim 1, characterized in that, The total number of partitions obtained after the second stress partitioning n zone The expression is: in, Indicates the number of angular units. Indicates the number of stress intervals.

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