Method for establishing wheel disc partition model based on stress distribution

Abstract

The invention relates to a method for establishing a wheel disc partition model based on stress distribution, which is used for improving the crack propagation calculation efficiency of different positions of a wheel disc so as to carry out failure risk assessment based on wheel disc stress partition. Specifically, finite element parametric modeling is adopted, a principal stress orthogonal plane is extracted to serve as a crack propagation plane, all stress components can be included in a calculation range, and the influence of asymmetric machining characteristics can be considered; based on a coordinate system conversion method, three-dimensional coordinates of points on a principal stress orthogonal plane are converted into two-dimensional coordinates, the dimensionality is reduced, and calculation steps are simplified; according to the method for establishing the wheel disc partition model based on stress distribution, rapid and automatic partition is achieved directly on the basis of stress and positions, efficiency is greatly improved, the areas are classified into the internal area, the surface area and the corner area, the risk difference of cracks in different positions of the wheel disc is considered, and the accuracy of the wheel disc partition model is improved. The final partitioning result is consistent with an example provided by the FAA airworthiness consultation notification in shape.

Description

Technical Field

[0001] The invention relates to the technical field of probabilistic damage tolerance assessment of aircraft engines, and in particular to a method for establishing a wheel partition model based on stress distribution. Background Art

[0002] Aircraft engine life-limited parts refer to the rotor and main stator structures that may endanger the safety of the engine due to primary failure. Once a life-limited part has a defect with a very small probability, its safety will be seriously threatened. Therefore, the US aviation industry has proposed a set of enhanced life management processes to ensure the safety of life-limited parts. The core of this process is to consider the defects with a very small probability of appearing in life-limited parts and conduct probabilistic damage tolerance assessment on them. This assessment method combines random factors such as defects, loads, and non-destructive testing to calculate the failure risk of aircraft engine life-limited parts and measure the safety of life-limited parts design solutions.

[0003] Taking the roulette wheel as an example, since the initial defect size and the position of the defect in the roulette wheel are both random, it is necessary to conduct a zoning study based on the stress distribution of the roulette wheel. The core is to perform stress analysis on the roulette wheel through finite element software, and then establish a zoning algorithm based on certain zoning criteria to obtain stress and zoning characteristics, so as to carry out failure risk assessment based on roulette wheel zoning. Therefore, it is necessary to form a method for establishing a roulette wheel stress zoning model: based on the finite element calculation results, develop a stress zoning algorithm, divide the roulette wheel into multiple areas with similar risks in the orthogonal plane of the principal stress, and finally conduct a failure risk assessment.

[0004] The latest partitioning method abroad is an automatic partitioning method based on pre-partitioning. This method pre-partitions finite elements with similar characteristics such as stress and temperature, including calculating risk surfaces, determining risk limit positions, 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, the present invention provides a method for establishing a wheel partition model based on stress distribution. The present invention adopts finite element parametric modeling, extracts the principal stress orthogonal plane as the crack propagation plane, includes all stress components in the calculation range, and considers the influence of asymmetric processing features; based on the coordinate system conversion method, the three-dimensional coordinates of the points on the principal stress orthogonal plane are converted into two-dimensional coordinates, reducing the dimension and simplifying the calculation steps; the present invention directly realizes rapid automatic partitioning based on stress and position, greatly improving the efficiency, and classifies the area into internal area, surface area and corner area at the same time. Based on stress similarity, surface area refinement and geometric continuity judgment, the partition results of the probability damage tolerance of the life-limited parts can be efficiently and accurately evaluated. The present invention considers the difference in the danger of cracks at different positions of the wheel, and the final partition result is consistent with the calculation example shape provided by the FAA airworthiness advisory circular. The present invention provides technical support for the probabilistic damage tolerance assessment of aircraft engine wheels, which has important engineering significance and practical value.

[0006] The present invention provides a method for establishing a wheel disk partition model based on stress distribution, comprising:

[0007] Step S1, establishing a finite element model of a roulette structure; applying a periodic external force to the finite element model of the roulette structure;

[0008] Step S2, determining the fatigue crack starting position of the wheel disc structure and the direction of the principal stress orthogonal plane and extracting the crack propagation plane, which is characterized as the principal stress orthogonal plane;

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

[0010] Step S3, performing dimensionality reduction processing on 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, dividing the principal stress orthogonal plane after the dimensionality reduction process into units, wherein each unit includes a plurality of nodes, a two-dimensional coordinate of each node, a corresponding relationship between each node, and a stress value of each node;

[0012] Step S5, identifying the unit type of each unit;

[0013] Step S6, obtaining the maximum stress value of each unit, and obtaining the maximum stress value of the principal stress orthogonal plane based on the maximum stress value of each unit;

[0014] Setting a stress value interval of a principal stress orthogonal plane based on a maximum stress value of the principal stress orthogonal plane;

[0015] Step S7, setting a stress gradient, and performing a first stress partitioning on the stress value interval according to the stress gradient;

[0016] Step S8, performing a second stress partition on the stress interval after the first stress partition according to the unit type, to obtain multiple stress partitions;

[0017] Step S9, let n=1, when n=1, it represents the first stress partition;

[0018] Step S10, based on the principle of geometric continuity, process each unit in the nth stress partition, determine whether there is a geometrically discontinuous unit in the corresponding stress partition, if so, create the n+1th stress partition based on the geometrically discontinuous unit, set n=n+1, and 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, repeating steps S9-S10, traversing each stress partition, obtaining multiple updated stress zones, and establishing a wheel disk structure partition model based on the multiple updated stress partitions.

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

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

[0023] Each intersection point is represented as a node of 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 of obtaining the three-dimensional coordinates of each node and the principal stress value of each node include:

[0025] Finite element software ABAQUS is used to obtain the maximum stress point of the finite element model of the wheel structure after external force is applied;

[0026] The maximum stress point is set as the fatigue crack initiation position, and the principal stress orthogonal plane direction is determined; the principal stress value of the wheel disc structure is obtained based on the third-order stress state equation of elastic mechanics and the fatigue crack initiation position;

[0027] Based on the fatigue crack starting position and the principal stress orthogonal plane direction, extract the principal stress orthogonal plane; characterize the principal stress orthogonal plane as a crack propagation plane;

[0028] Determine whether any two adjacent nodes in the finite element model of the wheel disc structure have intersections with the orthogonal plane of the principal stress, and obtain multiple intersections of the orthogonal plane of the principal stress and the finite element model of the wheel disc structure;

[0029] Represent each intersection point as each node of the orthogonal plane of the principal stress, and obtain the three-dimensional coordinates of each node;

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

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

[0032] Preferably, the unit types in step S5 are internal units, corner units and surface units.

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

[0034] Obtain the corresponding relationship between each node and the boundary nodes in each unit, and determine whether the number of boundary nodes in each unit is greater than 1. If so, the corresponding unit is a surface unit, otherwise, the corresponding unit is an internal unit;

[0035] Calculate the number of cells shared by each node in the surface cells or internal cells;

[0036] Determine whether the number of units shared by each node is equal to 1. If so, the corresponding node is a corner node and proceed to the next step. If not, proceed to the next step.

[0037] Determine whether each unit contains a corner node. If so, determine that the corresponding unit is a corner unit. If not, retain the original unit type.

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

[0039] Preferably, the specific steps of performing the second stress partitioning include:

[0040] Perform near-surface partitioning on each stress partition according to the unit type to obtain multiple internal stress partitions and multiple surface stress partitions;

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

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

[0043] Step S10-1, selecting the nth stress partition;

[0044] Step S10-2, determining whether the number of units in the nth stress partition is 1, if so, indicating that the stress partition is a geometrically continuous stress partition, and recording;

[0045] If not, mark all elements in the nth stress partition as surplus, select any element and mark it as source,

[0046] Step S10-3, searching for all adjacent cells to the source cell among the plurality of residual cells, and naming all adjacent cells as an adjacent source cell set;

[0047] Step S10-4, repeating step S10-3, traversing all the remaining units in the nth stress partition until no new unit can be found, judging whether there are any units in the corresponding stress partition that are not involved in the geometric continuity judgment, if so, it means that there are remaining units in the stress partition that are not adjacent to multiple geometric continuous units, creating a new partition based on the remaining units, obtaining the n+1th stress partition, setting n=n+1, and returning 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, repeat steps S10-1 to S10-4, and 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] Among them, n corner Indicates the number of corner units, n stress Represents the number of stress intervals.

[0053] The present invention also includes: step 12, performing failure risk assessment of the wheel disc based on the wheel disc stress partition model.

[0054] (1) The model of the present invention is based on the orthogonal plane of the principal stresses, all stress components are included in the calculation range, and the influence of asymmetric processing characteristics is considered;

[0055] (2) The present invention achieves the effect of reducing the calculation dimension and simplifying the steps by converting the three-dimensional coordinates of points on the orthogonal plane of the principal stress into two-dimensional coordinates;

[0056] (3) The present invention realizes rapid and automatic partitioning based on stress and position, with relatively higher calculation efficiency and lower calculation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings are only for the purpose of illustrating particular embodiments and are not to be construed as limiting the invention.

[0058] Figure 1 A schematic diagram of the process of boundary identification and unit classification in an embodiment of the present invention;

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

[0060] Figure 3 A schematic diagram of a stress partitioning process in an embodiment of the present invention;

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

[0062] Figure 5 It is a schematic diagram of the stress zoning result of the wheel disc in an embodiment of the present invention. DETAILED DESCRIPTION

[0063] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein, and therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0064] A specific embodiment of the present invention, as Figure 1-5 , discloses a method for establishing a wheel partition model based on stress distribution. In order to illustrate the effectiveness of the method proposed by the present invention, the above technical solution of the present invention is described in detail through a specific embodiment below. The specific implementation steps are as follows:

[0065] The present invention provides a method for establishing a wheel disk partition model based on stress distribution, comprising:

[0066] Step S1, establishing a finite element model of a wheel disc structure, and setting material parameters, boundary conditions and load conditions of the finite element model of the wheel disc structure;

[0067] Applying periodic external force to the finite element model of the wheel structure;

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

[0069] A master-slave surface setting method is used to apply periodic symmetrical external forces to the wheel structure;

[0070] The boundary conditions include the setting of the main surface, the secondary surface and the rotation axis of the wheel disc structure and the number of applied cycles; at the same time, axial constraints and circumferential constraints are applied on the flange surface;

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

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

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

[0074] Characterize each intersection point as each node of the principal stress orthogonal plane, and obtain the three-dimensional coordinates of each node; Obtain the principal stress values of each node through linear interpolation;

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

[0076] Use the finite element software ABAQUS to obtain the point with the maximum stress of the finite element model of the disk structure after applying the external force;

[0077] Set the point with the maximum stress as the fatigue crack initiation position, and determine the direction of the principal stress orthogonal plane; Obtain the principal stress values of the disk structure based on the third-order stress state equation of elasticity and the fatigue crack initiation position;

[0078] Based on the fatigue crack initiation position and the direction of the principal stress orthogonal plane, extract the principal stress orthogonal plane; Characterize the principal stress orthogonal plane as the crack propagation plane;

[0079] Judge whether there are intersection points between two adjacent nodes in the finite element model of the disk structure and the principal stress orthogonal plane, and obtain multiple intersection points of the principal stress orthogonal plane and the finite element model of the disk structure;

[0080] Characterize each intersection point as each node of the principal stress orthogonal plane, and obtain the three-dimensional coordinates of each node;

[0081] Calculate the stress value of each node through linear interpolation;

[0082] Further, the expression of the third-order stress state equation of elasticity is:

[0083]

[0084] where, σ 1 is the first principal stress or the maximum principal stress, σ 2 is the second principal stress, σ 3 is the third principal stress; I 1 is the first invariant of the stress tensor, I 2 is the second invariant of the stress tensor, I3 is the third invariant of the stress tensor; σ xx represents the normal stress acting in the x direction, σ yy represents the normal stress acting in the y direction, σ zz represents the normal stress acting in the z direction, σ xy represents the stress acting on the x-plane in the y direction, σ xz represents the stress acting on the x-plane in the z-direction, σ yz represents the stress acting on the y-plane in the z-direction.

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

[0086]

[0087] lσ xz +mσ yz +n(σ zz -σ 1 )=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 of the principal stress orthogonal plane is:

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

[0092] Among them, a represents the x-axis coordinate of the point with maximum principal stress, b represents the y-axis coordinate of the point with maximum principal stress, z represents the z-axis coordinate of the node, c represents the z-axis coordinate of the point with maximum principal stress, and (x, y, z) represents the coordinates of the node on the orthogonal plane of principal stress, among which 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] Exemplarily, the expressions of the relationship points between the i-th node and the j-th node adjacent to the principal stress orthogonal plane of the finite element model of the wheel structure are respectively:

[0094]

[0095] Among them, s i is the relationship point between the i-th node of the finite element model of the wheel structure and the orthogonal plane of the principal stress, s j is the relationship point between the jth node of the finite element model of the wheel structure and the orthogonal plane of the principal stress, x irepresents the x-axis coordinate of the ith node of the finite element model of the roulette structure, y i represents the y-axis coordinate of the i-th node of the finite element model of the roulette structure, z represents the z-axis coordinate of the i-th node of the finite element model of the roulette structure, and x j represents the x-axis coordinate of the jth node of the finite element model of the roulette structure, and y j represents the y-axis coordinate of the jth node of the finite element model of the roulette structure, z j Represents the z-axis coordinate of the j-th node.

[0096] Furthermore, the specific steps of obtaining multiple intersection points include:

[0097] Obtain the relationship points between each two adjacent nodes and the principal stress orthogonal plane in the finite element model of the wheel structure i and relationship point 2s j ;

[0098] Set the basis for intersection determination;

[0099] If i ×s j <0, the two adjacent nodes are located on the opposite sides of the principal stress orthogonal plane, and the line segment formed by the two nodes has an intersection with the principal stress orthogonal plane;

[0100] If i ×s j >0, the two adjacent nodes are located on the same side of the principal stress orthogonal plane, and the line segment formed by the two nodes has no intersection with the principal stress orthogonal plane;

[0101] If i ×s j =0, then one of the two adjacent nodes is located 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, the total stress value of each intersection point is obtained, and the specific steps include:

[0103] Respectively obtain the relationship points between the i-th node and the j-th node adjacent to the finite element model of the wheel structure and the orthogonal plane of the principal stress;

[0104] Based on the relationship points between the i-th node and the j-th node of the finite element model of the wheel structure and the orthogonal plane of the principal stress, the equations of the lines between the i-th node and the j-th node adjacent to each other are established, and the intersection point (x ij ,y ij ,z ij );

[0105] Calculate the intersection point (x) by linear interpolationij ,y ij ,z ij ) three-dimensional stress components; and obtaining the principal stress value of the intersection based on the three-dimensional stress components.

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

[0107] Taking two nodes on the plane determined by the z coordinate as an example, the equation of the straight line between the 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 ) is expressed as:

[0110]

[0111] Among them, σ xxij is the intersection point (x ij ,y ij ,z ij ) stress on the x-axis; σ xxj is the stress of node j on the x-axis; σ xxi is the stress of node i on the x-axis; ij Represents the x-axis coordinate of the intersection 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] Among them, σ xx is the stress of the adjacent node on the x-axis, σ yy is the stress of the adjacent node on the y-axis, σ zz is the stress of the adjacent node in the z-axis, σ yz is the stress acting on the x-plane in the y direction, σxz is the stress acting on the x-plane in the z-direction, σ xy is the stress acting on the y-plane in the z-direction.

[0115] Step S3, performing dimensionality reduction processing on 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 the coordinate axis Vector x, the coordinate axis Vector y and the normal vector Vector z of the orthogonal plane of the principal stress and construct a two-dimensional coordinate system;

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

[0119] Inverting the coordinate transformation matrix T to obtain an inverted coordinate matrix; using the inverted coordinate matrix to obtain the two-dimensional coordinates of each node;

[0120] Furthermore, the coordinate transformation matrix T is expressed as:

[0121]

[0122] Among them, W x The variable representing the x direction of the coordinate axis Vector z, W y The variable representing the y direction of the coordinate axis Vector z, W z A variable representing the z direction of the coordinate axis Vector z;

[0123] U x The variable representing the x direction of the coordinate axis Vector x, U y The variable representing the y direction of the coordinate axis Vector x, U z A variable representing the z direction of the coordinate axis Vector x;

[0124] V x V is the variable representing the x direction of the coordinate axis Vector y. y V is the variable representing the y direction of the coordinate axis Vector y. z A variable representing the z direction of the coordinate axis Vector y; Vector z = (W x ,W y ,W z ) represents the normal vector direction cosine on the plane orthogonal to the principal stress. As mentioned above, Vector z=(W x ,W y ,W z)=(l,m,n); and Vector x=(U x ,U y ,U z )、Vector y=(V x ,V y ,V z ) One way to determine the direction vectors on the two principal stress orthogonal planes is as follows: The node coordinate information of the principal stress orthogonal planes is known, and one of the points (x 0 ,y 0 ,z 0 ) as the origin of the new coordinate system, and then randomly select another point (x 1 ,y 1 ,z 1 ), and (x 1 -x 0 ,y 1 -y 0 ,z 1 -z 0 ) as the x-axis direction vector in the new coordinate system, that is, Vector x.

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

[0126] Vector y=Vector x×Vector z=(x 1 -x 0 ,y 1 -y 0 ,z 1 -z 0 )×(l,m,n) (9)

[0127] Step S4, dividing the principal stress orthogonal plane after the dimensionality reduction process into units, wherein each unit includes a plurality of nodes, a two-dimensional coordinate of each node, a corresponding relationship between each node, and a stress value of each node;

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

[0129] It can be understood that the node N i The two-dimensional coordinates of Ni ,y Ni );

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

[0131] The unit node correspondence relationship is f(N i,1 ,N i,2 ,N i,3 ,N i,4 )=E r , E r Represents unit r, corresponding to four nodes N i,1 、N i,2 、N i,3 、N i,4 ;

[0132] Each node N in the unit i , divided into corner nodes, surface nodes or internal nodes according to their locations, and the number of units connected to each node is n i is 1, 2 / 3, 4, and the expressions are g 1 (E i,1 )=N i , g 1 (E i,1 ) indicates that a unit node connects a unit; g 2 (E i,1 ,E i,2 )=N i , g 2 (E i,1 ,E i,2 ) indicates that a unit node connects two units; g 3 (E i,1 ,E i,2 ,E i,3 )=N i g 3 (E i,1 ,E i,2 ,E i,3 ) indicates that the unit node connection is three units; g 4 (E i,1 ,E i,2 ,E i,3 ,E i,4 )=N i g 4 (E i,1 ,E i,2 ,E i,3 ,E i,4 ) indicates that a unit node connects four units, where a node is a boundary node when the number of units connected to it is 1 and / or 2 / 3.

[0133] It can be understood that the coordinates of the boundary nodes are the set of all discrete boundary node coordinates in the roulette partition model L = {(x, y)|(x 1 ,y 1 ),...,(x p ,y p ),...,(xq ,y q )}(2≤p≤q), where q represents the number of boundary nodes.

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

[0135] Furthermore, the unit centroid coordinate (x E ,y E ), unit volume V E , unit stress σ E , unit temperature T E The expressions are:

[0136]

[0137] Among them, x Ni represents the x-axis coordinate of node i on the element, y Ni represents the y-axis coordinate of node i on the element, σ i represents the stress at node i on the element, T i represents the temperature of node i on the unit, x max Indicates the maximum x-axis coordinate of node i on the element, x min Indicates the maximum x-axis coordinate of node i on the element, y max Indicates the maximum value of the y-axis coordinate of node i on the element, y min Represents the minimum y-axis coordinate of node i on the element.

[0138] Preferably, the unit classification includes internal units, surface units and corner units, and t(E j )=1、t(E j )=2 and t(E j )=3 indicates the unit type. Traverse each unit E j , judge the number of boundary nodes among the four nodes of the unit to distinguish internal units from surface units; if a unit contains at least one corner node, then the unit is defined as a corner unit. The details are as follows:

[0139] Preferably, the unit classification includes internal units, surface units and corner units, and traversing each unit E j , judge the number of boundary nodes among the four nodes of the unit to distinguish internal units from surface units; if a unit contains at least one corner node, then the unit is defined as a corner unit. The details are as follows:

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

[0141]

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

[0143] Step S5, identifying the unit type of each unit;

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

[0145] Obtain the corresponding relationship between each node and the boundary nodes in each unit, and determine whether the number of boundary nodes in each unit is greater than 1. If so, the corresponding unit is a surface unit, otherwise, the corresponding unit is an internal unit;

[0146] Calculate the number of cells shared by each node in the surface cells or internal cells;

[0147] Determine whether the number of units shared by each node is equal to 1. If so, the corresponding node is a corner node and proceed to the next step. If not, proceed to the next step.

[0148] Determine whether each unit contains a corner node. If so, determine that the corresponding unit is a corner unit. If not, retain the original unit type.

[0149] Step S6, obtaining the maximum stress value of each unit, and obtaining the maximum stress value of the principal stress orthogonal plane based on the maximum stress value of each unit;

[0150] Setting a stress value interval of a principal stress orthogonal plane based on a maximum stress value of the principal stress orthogonal plane;

[0151] Step S7, setting a stress gradient, and performing a first stress partitioning on the stress value interval according to the stress gradient; the first stress partitioning is to divide nodes with similar stress values ​​into corresponding stress partitions;

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

[0153]

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

[0155] Step S8, performing a second stress partition on the stress interval after the first stress partition according to the unit type, to obtain multiple stress partitions;

[0156] The stress partitions include internal stress partitions, surface stress partitions and corner unit stress partitions;

[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] Among them, n corner Indicates the number of corner elements.

[0160] Preferably, the specific steps of performing the second stress partitioning include:

[0161] Perform near-surface partitioning on each stress partition according to the unit type to obtain multiple internal stress partitions and multiple surface stress partitions;

[0162] After the 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 partition;

[0164] Step S10, based on the principle of geometric continuity, process each unit in the nth stress partition, determine whether there is a geometrically discontinuous unit in the corresponding stress partition, if so, create the n+1th stress partition based on the geometrically discontinuous unit, set n=n+1, and update the total number of stress intervals N, and return to step S9;

[0165] If not, the nth updated stress partition is obtained and recorded, and the next step is entered; specifically, step S10, processing each unit in the nth stress partition based on the principle of geometric continuity, and the specific steps of obtaining the nth updated stress partition include:

[0166] Step S10-1, selecting the nth stress partition;

[0167] Step S10-2, determining whether the number of units in the nth stress partition is 1, if so, indicating that the stress partition is a geometrically continuous stress partition, and recording;

[0168] If not, mark all elements in the nth stress partition as surplus, select any element and mark it as source,

[0169] Step S10-3, in multiple left units0 Search for the source unit Sourse s All adjacent units are named as the adjacent source unit set Sourse s+1 ;

[0170] Step S10-4, repeating step S10-3, traversing all the remaining units in the nth stress partition until no new unit can be found, judging whether there are any units in the corresponding stress partition that are not involved in the geometric continuity judgment, if so, it means that there are remaining units in the stress partition that are not adjacent to multiple geometric continuous units, creating a new partition based on the remaining units, obtaining the n+1th stress partition, setting n=n+1, and returning 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, repeat steps S10-1 to S10-4, and obtain multiple updated stress partitions.

[0173] Step S11, repeating steps S9-S10, traversing each stress partition, obtaining multiple updated stress zones, and establishing a wheel disk structure partition model based on the multiple updated stress partitions.

[0174] Exemplarily, the specific steps of the unit adjacency criterion include: taking any two units E 1 、E 2 For example, E 1 The corresponding node set can be expressed as A 1 = {N 1,1 ,N 1,2 ,N 1,3 ,N 1,4}, E 2 The corresponding node set can be expressed as A 2 = {N 2,1 ,N 2,2 ,N 2,3 ,N 2,4}, let B = A 1 ∪A 2 If |B|=6, then unit E 1 、E 2 There are 2 common nodes, which are adjacent units; if |B|=7, then unit E 1 、E 2 There is one common node, which is a diagonal unit rather than an adjacent unit; if |B|=8, then unit E 1 、E 2 There are no common nodes, neither diagonal cells nor adjacent cells.

[0175] The present invention also includes: step 12, performing failure risk assessment of the wheel disc based on the wheel disc stress partition model.

[0176] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for establishing a wheel partition model based on stress distribution, characterized in that: include: Step S1, establishing a finite element model of a wheel structure; Applying periodic external force to the finite element model of the wheel structure; Step S2, determining the fatigue crack starting position of the wheel disc structure and the direction of the principal stress orthogonal plane and extracting the crack propagation plane, which is characterized as the principal stress orthogonal plane; Obtain the three-dimensional coordinates of each node on the principal stress orthogonal plane and the principal stress value of each node; Step S3, performing dimensionality reduction processing on the three-dimensional coordinates of each node in the principal stress orthogonal plane to obtain the two-dimensional coordinates of each node; Step S4, dividing the principal stress orthogonal plane after the dimensionality reduction process into units, wherein each unit includes a plurality of nodes, a two-dimensional coordinate of each node, a corresponding relationship between each node, and a stress value of each node; Step S5, identifying the unit type of each unit; Step S6, obtaining the maximum stress value of each unit, and obtaining the maximum stress value of the principal stress orthogonal plane based on the maximum stress value of each unit; Setting a stress value interval of a principal stress orthogonal plane based on a maximum stress value of the principal stress orthogonal plane; Step S7, setting a stress gradient, and performing a first stress partitioning on the stress value interval according to the stress gradient; Step S8, performing a second stress partition on the stress interval after the first stress partition according to the unit type, to obtain multiple stress partitions; Step S9, let n=1, when n=1, it represents the first stress partition; Step S10, based on the principle of geometric continuity, process each unit in the nth stress partition, determine whether there is a geometrically discontinuous unit in the corresponding stress partition, if so, create the n+1th stress partition based on the geometrically discontinuous unit, set n=n+1, and update the total number of stress intervals N, and return to step S9; If not, obtain the nth updated stress partition, record it, and proceed to the next step; Step S11, repeating steps S9-S10, traversing each stress partition, obtaining multiple updated stress zones, and establishing a wheel disk structure partition model based on the multiple updated stress partitions.

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

3. The method for establishing a wheel disk partition model based on stress distribution according to claim 2, characterized in that: The specific steps of obtaining the three-dimensional coordinates of each node include: Finite element software ABAQUS is used to obtain the maximum stress point of the finite element model of the wheel structure after external force is applied; The maximum stress point is set as the fatigue crack initiation position, and the principal stress orthogonal plane direction is determined; the principal stress value of the wheel disc structure is obtained based on the third-order stress state equation of elastic mechanics and the fatigue crack initiation position; Based on the fatigue crack starting position and the principal stress orthogonal plane direction, extract the principal stress orthogonal plane; characterize the principal stress orthogonal plane as a crack propagation plane; Determine whether any two adjacent nodes in the finite element model of the wheel disc structure have intersections with the orthogonal plane of the principal stress, and obtain multiple intersections of the orthogonal plane of the principal stress and the finite element model of the wheel disc structure; Represent each intersection point as each node of the orthogonal plane of the principal stress, and obtain the three-dimensional coordinates of each node; The stress value at each node is calculated by linear interpolation.

4. The method for establishing a 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 units connected by the boundary nodes is 1 and / or 2 / 3.

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

6. The method for establishing a wheel partition model based on stress distribution according to claim 4, characterized in that: The specific steps to identify the unit type of each unit include: Obtain the corresponding relationship between each node and the boundary nodes in each unit, and determine whether the number of boundary nodes in each unit is greater than 1. If so, the corresponding unit is a surface unit, otherwise, the corresponding unit is an internal unit; Calculate the number of cells shared by each node in the surface cells or internal cells; Determine whether the number of units shared by each node is equal to 1. If so, the corresponding node is a corner node and proceed to the next step. If not, proceed to the next step. Determine whether each unit contains a corner node. If so, determine that the corresponding unit is a corner unit. If not, retain the original unit type.

7. The method for establishing a wheel partition model based on stress distribution according to claim 1, characterized in that: The first stress partitioning in step S7 is to divide nodes with similar stress values ​​into corresponding stress partitions.

8. The method for establishing a wheel partition model based on stress distribution according to claim 1, characterized in that: The specific steps for the second stress partitioning include: Perform near-surface partitioning on each stress partition according to the unit type to obtain multiple internal stress partitions and multiple surface stress partitions; After the near-surface partitioning, the remaining elements are partitioned into corner elements to obtain multiple corner element stress partitions.

9. The method for establishing a wheel partition model based on stress distribution according to claim 1, characterized in that: The specific steps of obtaining the nth updated stress partition in step S10 include: Step S10-1, selecting the nth stress partition; Step S10-2, determining whether the number of units in the nth stress partition is 1, if so, indicating that the stress partition is a geometrically continuous stress partition, and recording; If not, mark all elements in the nth stress partition as surplus, select any element and mark it as source, Step S10-3, searching for all adjacent cells to the source cell among the plurality of residual cells, and naming all adjacent cells as an adjacent source cell set; Step S10-4, repeating step S10-3, traversing all the remaining units in the nth stress partition until no new unit can be found, judging whether there are any units in the corresponding stress partition that are not involved in the geometric continuity judgment, if so, it means that there are remaining units in the stress partition that are not adjacent to multiple geometric continuous units, creating a new partition based on the remaining units, obtaining the n+1th stress partition, setting n=n+1, and returning to step S10-1; If not, it means that the corresponding stress partition has geometric continuity, and the nth updated stress partition is obtained; Step S10-5, traverse each stress partition, repeat steps S10-1 to S10-4, and obtain multiple updated stress partitions.

10. The method for establishing a 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 is n zone , the expression is: <h2 style=";text-align:left;direction:ltr">n<h2 style=";text-align:left;direction:ltr"> zone <h2 style=";text-align:left;direction:ltr"> <2n<h2 style=";text-align:left;direction:ltr"> stress <h2 style=";text-align:left;direction:ltr"> +n<h2 style=";text-align:left;direction:ltr"> corner Among them, n corner Indicates the number of corner units, n stress Represents the number of stress intervals.

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