Engine rotor blade plane stress element mesh conversion method and system

Abstract

This invention relates to a method and system for converting plane stress element meshes for engine rotor blades. The method includes setting up 3D element arrays and 2D element arrays; traversing the node numbers of all elements in all layers of the 3D element array to obtain the overall 2D node number and calculating its coordinate values; calculating the element node number of the 2D element based on the overall 2D element node number; traversing the nodes of all elements in all layers of the 3D element array to calculate the volume of the 3D element array, and traversing the nodes of the 2D element array to calculate the area of ​​the 2D element array; calculating the thickness of the 2D element array based on the volume of the 3D element array and the area of ​​the 2D element array; and outputting the node coordinates and element information of the 2D element array. This invention can automatically convert aero-engine rotor blades from 20-node hexahedral solid element meshes to 8-node quadrilateral plane stress element meshes, thereby saving a significant amount of manpower, greatly shortening the calculation cycle, and providing a foundation for subsequent high-precision finite element calculations and optimization design of the rotor.

Description

Technical Field

[0001] This invention relates to the field of engine dynamics design, and in particular to a method and system for converting plane stress element meshes for engine rotor blades. Background Technology

[0002] The rotor disc of an aero engine operates at high speeds, and its strength is directly related to the engine's safety, making it a primary and critical component. For example... Figure 1 As shown, 2D ring elements, such as 8-node quadrilateral ring elements, are often used in engine disk strength calculations. This type of element is the most accurate among commonly used 2D elements in finite element analysis. 2D elements of the same order (e.g., 2D 8-node quadrilateral second-order elements) are more accurate than 3D elements (20-node hexahedral second-order elements). Because the computational scale of 2D elements is much smaller than that of 3D elements, the mesh can be very small (see...). Figure 2 Therefore, the calculation accuracy can be further improved compared to using 3D elements, especially for small rounded areas with large shape changes, see [reference needed]. Figure 2 As shown. To account for the interaction between the disks, rotor assemblies with multiple disks are often used, or... Figure 1 As shown, when calculating the entire engine rotor disk together, using 2D elements has a significant advantage over using 3D elements. In disk structure optimization design or elastoplastic analysis, using 2D elements can save a considerable amount of time compared to using 3D elements; therefore, using 2D elements also has a clear advantage over 3D elements.

[0003] Therefore, there is an urgent need to provide a method for converting plane stress element meshes for engine rotor blades to overcome the problems existing in the prior art. Summary of the Invention

[0004] Therefore, the technical problem to be solved by this invention is to overcome the technical defects existing in the prior art, and to propose a method and system for converting plane stress element mesh of engine rotor blades. This method can realize the automatic conversion of aero-engine rotor blades from 20-node hexahedral solid element mesh to 8-node quadrilateral plane stress element mesh, thereby saving a lot of manpower, greatly shortening the calculation cycle, and providing a foundation for subsequent high-precision finite element calculation and optimization design of rotors.

[0005] To address the aforementioned technical problems, this invention provides a method for converting plane stress element meshes for engine rotor blades, comprising the following steps:

[0006] S1: Set up the 3D cell array and the 2D cell array, input the node number of each 3D cell and save it in the 3D cell array;

[0007] S2: Traverse the node numbers of all cells in all layers of the 3D cell to obtain the node numbers of the 2D cell, and calculate the coordinate values ​​of the node numbers of the 2D cell;

[0008] S3: Calculate the unit node number of the 2D unit based on the overall 2D node number and store it in the 2D unit array;

[0009] S4: Traverse all nodes of all cells in all layers of the 3D cell, calculate the volume of the 3D cell, and traverse all nodes of the 2D cell, calculate the area of ​​the 2D cell.

[0010] S5: Calculate the thickness of the 2D unit based on the volume of the 3D unit and the area of ​​the 2D unit;

[0011] S6: Output the node coordinates and element information of the 2D element.

[0012] In one embodiment of the present invention, the method for obtaining the node number of the 2D unit by traversing the node numbers of all units in all layers of the 3D unit in step S2 includes:

[0013] The sorting method of the 3D units is specified to be the same as that of the 2D units, wherein the sorting method is to arrange them from left to right first, and then from bottom to top.

[0014] Let the number of elements in each layer be NC, and the total number of layers be NL. Let i = 1, 2, ..., NL be the layer numbers from bottom to top, j = 1, 2, ..., NC be the sorting numbers of the elements in each layer from left to right, and L be the 2D element node number. Then we have:

[0015] For 3D element local node number 12:

[0016] L=(i-1)(3NC+2)+2(j-1)+1

[0017] For the local node numbers 9 and 11 of the 3D element, we have:

[0018] L=(i-1)(3NC+2)+2(j-1)+2

[0019] For the local node numbers 17 and 20 of the 3D element, we have:

[0020] L=(i-1)(3NC+2)+2NC+j+1

[0021] When i = 1, and j increases from 1 to j = NC, nodes 1 to 12 and 14 to 19 are obtained. Then, j = NC + 1 is set to obtain nodes 13 and 20. At this point, all nodes 1 to 20 of the first layer are obtained. Then, all node numbers of the remaining layers are obtained.

[0022] In one embodiment of the present invention, the method for calculating the coordinate value of the 2D element node number in step S2 is as follows:

[0023] The node coordinates of the 2D element obtained by traversing the node numbers of all elements in all layers of the 3D element are still Cartesian coordinates in space. The Cartesian coordinates of the nodes are converted to cylindrical coordinates using the following formula:

[0024]

[0025] X i =X i

[0026] Among them, (r i ,x i (x) represents the cylindrical coordinates of the node. i y i , z i ) represents the rectangular coordinates of the node.

[0027] In one embodiment of the present invention, step S3, the method for calculating the element node number of the 2D element based on the 2D overall node number and storing it in the 2D element array, includes:

[0028] Let the 2D cell array be E2d[][], then we have:

[0029] Ie=i×NC+j

[0030] E2d[Ie][1]=(i-1)(3NC+2)+2(j-1)+1

[0031] E2d[Ie][2]=E2d[Ie][1]+2

[0032] E2d[I e][5]=E2d[I e][1]+1

[0033] E2d[I e][8]=(i-1)(3NC+2)+2NC+j+1

[0034] E2d[I e][6]=E2d[I e][8]+1

[0035] E2d[I e][4]=E2d[I e][1]+3NC+2

[0036] E2d[I e][3]=E2d[I e][4]-2

[0037] E2d[I e][7]=E2d[I e][4]-1

[0038] Where i = 1, 2, ..., NL, j = 1, 2, ..., NC, and I e is the unit number.

[0039] In one embodiment of the present invention, the method for calculating the volume of the 3D unit by traversing the nodes of all units in all layers of the 3D unit in step S4 includes:

[0040] The nodes of the 3D unit are transformed from local coordinates to global Cartesian coordinates using isoparametric transformation, with the local coordinates located at the center of the cube. The coordinate transformation formula is as follows:

[0041]

[0042]

[0043] Among them, (x i y i , z i () represents the rectangular coordinates of the node, (ξ, η, ζ) represents the local coordinates, and N represents the coordinates of the node. i Represents a shape function;

[0044] The volume of a 3D element is calculated based on the local coordinates (ξ, η, ζ) of the node, using the following formula:

[0045]

[0046] in:

[0047]

[0048]

[0049]

[0050]

[0051] In one embodiment of the present invention, step S4, which involves traversing all nodes in the 2D unit and calculating the area of ​​the 2D unit, includes:

[0052] The nodes of the 2D unit are transformed from local coordinates to global Cartesian coordinates using an isoparametric transformation. The local coordinates are located at the center of the square. The coordinate transformation formula is as follows:

[0053]

[0054]

[0055] Among them, (r i ,x i () represents the cylindrical coordinates of the nodes, (ξ, η) represents the local coordinates, and N... i Represents a shape function;

[0056] The area of ​​a 2D element is calculated based on the local coordinates (ξ, η) of the node, using the following formula:

[0057]

[0058] in:

[0059]

[0060]

[0061]

[0062]

[0063]

[0064] In one embodiment of the present invention, in step S5, the formula for calculating the thickness of the 2D unit is:

[0065] H j =N×V 3D / A 2D

[0066] Among them, V 3D For the volume of a 3D unit, A 2D Let N be the area of ​​the corresponding 2D unit.

[0067] Furthermore, the present invention also provides a plane stress element mesh conversion system for engine rotor blades, comprising:

[0068] The array setting module is used to set the 3D cell array and the 2D cell array. It inputs the node number of each 3D cell and saves it in the 3D cell array.

[0069] The 2D unit coordinate calculation module is used to traverse the node numbers of all units in all layers of the 3D unit to obtain the node number of the 2D unit, and calculate the coordinate value of the node number of the 2D unit.

[0070] The 2D unit node numbering module is used to calculate the unit node number of the 2D unit based on the overall 2D node number and store it in the 2D unit array.

[0071] The calculation module is used to traverse the nodes of all units in all layers of the 3D unit, calculate the volume of the 3D unit, and traverse the nodes of the 2D unit to calculate the area of ​​the 2D unit; and calculate the thickness of the 2D unit based on the volume of the 3D unit and the area of ​​the 2D unit.

[0072] The 2D unit information output module is used to output the node coordinates and unit information of the 2D unit.

[0073] Furthermore, the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described method for converting plane stress element meshes for engine rotor blades.

[0074] Furthermore, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method for converting plane stress element meshes for engine rotor blades.

[0075] The technical solution of the present invention has the following advantages compared with the prior art:

[0076] The present invention discloses a method and system for converting plane stress element meshes for engine rotor blades. This method can automatically convert the mesh of aero-engine rotor blades from 20-node hexahedral solid element meshes to 8-node quadrilateral plane stress element meshes, thereby saving a lot of manpower, greatly shortening the calculation cycle, and providing a foundation for subsequent high-precision finite element calculations and optimization design of rotors. Attached Figure Description

[0077] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0078] Figure 1 This is a schematic diagram of a 2D unit of an engine rotor.

[0079] Figure 2 This is a flowchart illustrating a method for converting planar stress element meshes for engine rotor blades, as proposed in an embodiment of the present invention.

[0080] Figure 3 This is a 20-node hexahedral 3D unit mesh of a blade proposed in an embodiment of the present invention.

[0081] Figure 4 This is an 8-node quadrilateral 2D unit mesh transformed from 3D units, as proposed in this embodiment of the invention.

[0082] Figure 5 This is a schematic diagram of a 20-node hexahedral 3D unit of a blade proposed in an embodiment of the present invention.

[0083] Figure 6 This is a schematic diagram of an 8-node quadrilateral 2D unit obtained by averaging the thickness direction according to an embodiment of the present invention.

[0084] Figure 7This is a schematic diagram of the 3D unit sorting method proposed in an embodiment of the present invention.

[0085] Figure 8 This is a schematic diagram of the 2D unit sorting method proposed in an embodiment of the present invention.

[0086] Figure 9 This is a schematic diagram of a rectangular unit proposed in an embodiment of the present invention.

[0087] Figure 10 This is a schematic diagram of the 8-node surface element proposed in this embodiment of the invention, which is transformed from local coordinates to global rectangular coordinates through isoparametric transformation.

[0088] Figure 11 This is a schematic diagram of the 20-node volume element proposed in this embodiment of the invention, which is transformed from local coordinates to global rectangular coordinates through isoparametric transformation. Detailed Implementation

[0089] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0090] Reference Figure 2 As shown in the figure, an embodiment of the present invention provides a method for converting plane stress element meshes for engine rotor blades, which includes the following steps:

[0091] S1: Set up the 3D cell array and the 2D cell array, input the node number of each 3D cell and save it in the 3D cell array;

[0092] S2: Traverse the node numbers of all cells in all layers of the 3D cell to obtain the node numbers of the 2D cell, and calculate the coordinate values ​​of the node numbers of the 2D cell;

[0093] S3: Calculate the unit node number of the 2D unit based on the overall 2D node number and store it in the 2D unit array;

[0094] S4: Traverse all nodes of all cells in all layers of the 3D cell, calculate the volume of the 3D cell, and traverse all nodes of the 2D cell, calculate the area of ​​the 2D cell.

[0095] S5: Calculate the thickness of the 2D unit based on the volume of the 3D unit and the area of ​​the 2D unit;

[0096] S6: Output the node coordinates and element information of the 2D element.

[0097] The present invention discloses a method for converting plane stress element meshes for engine rotor blades. This method can automatically convert aero-engine rotor blades from 20-node hexahedral solid element meshes to 8-node quadrilateral plane stress element meshes, thereby saving a lot of manpower, greatly shortening the calculation cycle, and providing a foundation for subsequent high-precision finite element calculations and optimization design of rotors.

[0098] The following detailed implementation method illustrates the specific content of the engine rotor blade planar stress element mesh conversion method proposed in this invention.

[0099] As an example, this embodiment first generates as follows: Figure 3 The 20-node hexahedral 3D element mesh shown here needs to be implemented to... Figure 4 The transformation of the 8-node quadrilateral 2D cell mesh is shown.

[0100] Figure 5 The image shows a schematic diagram of a 20-node hexahedral 3D element for a blade, which is converted into a thickness-oriented averaging method as shown below. Figure 6 The 8-node quadrilateral 2D element shown. Figure 5 There are four midpoints (12, 10, 14, 16) along the thickness direction, and their coordinates can be directly used as the coordinates of the corner nodes of the 2D element (corresponding to...). Figure 6 (nodes 1, 2, 3, and 4) Figure 6 The dashed lines represent 2D surface elements. The average of the coordinates of the midpoints of the edges in the other two directions on a 20-node hexahedron can be used as the midpoints of the surface element's edges. For example, the average coordinates of 9 and 11; 18 and 19; 13 and 15; and 17 and 20 correspond to the midpoints of the edges of the surface element. Figure 6 The coordinates of nodes 5, 6, 7, and 8.

[0101] The 2D unit blade after the above transformation is a spatial curved surface, and its node coordinates are still spatial rectangular coordinates. Therefore, it needs to be further converted to cylindrical coordinates (r,x) in a cylindrical coordinate system, where r is radial and x is axial. The node rectangular coordinates are converted to cylindrical coordinates using the following equation (1):

[0102]

[0103] x i =x i (1)

[0104] Among them, (r i ,x i (x) represents the cylindrical coordinates of the node. i y i , z i ) represents the rectangular coordinates of the node.

[0105] The above Figure 5The local node coordinates of the 3D element shown are... Figure 6 The coordinate correspondence of local nodes in the 2D element is shown in Table 1. Coordinate transformation from 3D to 2D elements can be performed according to this table. Note that "local nodes" are distinct from "global nodes," as shown below. Figure 5 and Figure 6 The node numbers marked above are local node numbers; for the overall node numbers of the element, see [link to relevant documentation]. Figure 10 ,For example Figure 10 The overall node numbers of Unit 1 are 1,3,23,21,2,15,22,14, and its local node numbers are 1,2,3,4,5,6,7,8.

[0106] Table 1. Correspondence between local node coordinates of 3D elements and local node coordinates of 2D elements

[0107] Figure 6 2D element node number Figure 5 3D unit node number Coordinate calculation 1 12 equal 2 10 equal 3 14 equal 4 16 equal 5 9、11 average value 6 18、19 average value 7 13、15 average value 8 17、20 average value

[0108] In step S2, as Figure 7 As shown, the 3D unit arrangement is specified as numbering from the inlet (left side of the figure) to the outlet (right side of the figure), and sequentially from the leaf root to the leaf tip. Figure 7 (From bottom to top) increases, see [reference] Figure 4 Its element node local numbering is as follows: Figure 7 As shown in Unit 1. The corresponding 2D unit's element and overall node sorting method is as follows: Figure 8 As shown. By Figure 8 It can be seen that the unit number of the 2D unit is sorted in the same way as the unit number of the 3D unit. The node sorting method of the 2D unit is to sort from left to right first, and then sort them layer by layer upwards.

[0109] like Figure 4 As shown, let the number of elements in each layer be NC, with a total of NL layers, where i = 1, 2, ..., NL are the layer numbers from bottom to top, j = 1, 2, ..., NC are the sorting numbers of each layer's elements from left to right, and L is the 2D element node number. Then we have:

[0110] For 3D element local node number 12 (see...) Figure 7 (bottom left corner)

[0111] L=(i-1)(3NC+2)+2(j-1)+1 (2)

[0112] For 3D unit local node numbers 9 and 11, there are

[0113] L=(i-1)(3NC+2)+2(j-1)+2 (3)

[0114] For 3D element local node numbers 17 and 20, there are

[0115] L=(i-1)(3NC+2)+2NC+j+1 (4)

[0116] When i = 1, and j increases from 1 to j = NC, for example... Figure 8 As shown, nodes 1-12 and 14-19 can be obtained. Now, let j = NC+1, and calculate the node numbers 13 and 20 using equations (1) and (4). At this point, all nodes 1-20 of the first layer have been obtained. Next, when i = 2, i.e., the second layer is calculated, nodes 21-40 can be obtained; when i = 3, nodes 41-60 can be obtained.

[0117] Assuming NL = 3, nodes 61 to 73 are still unobtained. To address this, we set i = NL + 1 and repeat the above calculations using equations (2) and (3) to obtain the remaining nodes 61 to 73.

[0118] In step S3, let the 2D cell array be E2d[][], then we have:

[0119] Ie=i×NC+j

[0120] E2d[Ie][1]=(i-1)(3NC+2)+2(j-1)+1

[0121] E2d[Ie][2]=E2d[Ie][1]+2

[0122] E2d[Ie][5]=E2d[Ie][1]+1

[0123] E2d[Ie][8]=(i-1)(3NC+2)+2NC+j+1

[0124] E2d[Ie][6]=E2d[Ie][8]+1

[0125] E2d[Ie][4]=E2d[Ie][1]+3NC+2

[0126] E2d[Ie][3]=E2d[Ie][4]-2

[0127] E2d[Ie][7]=E2d[Ie][4]-1 (5)

[0128] Where: i = 1, 2, ..., NL; j = 1, 2, ..., NC; Ie is the unit number.

[0129] Element thickness is an important parameter of plane stress elements. It is uniform for a single element, but the thickness of different elements on a blade can be different.

[0130] A simple approximate method for calculating element thickness is as follows:

[0131] Let (x)i1 y i1 , z i1 ) and (x i2 y i2 , z i2 )for Figure 5 The thickness of the surface element (single blade) at the two nodes shown in the upper left corner is:

[0132]

[0133] The other 7 points are calculated in the same way according to formula (6), and then the average value is multiplied by the number of blades to get the thickness of the unit (all blades).

[0134]

[0135] Where N is the number of blades in the impeller, that is, the thickness here is the sum of the thicknesses of all blades, and j is the unit number.

[0136] Since the blade solid unit may be twisted, equation (7) will have a large error.

[0137] The accurate formula for calculating the thickness of a 2D element is as follows:

[0138] H j =N×V 3D / A 2D (8)

[0139] Among them, V 3D For the volume of a 3D unit, A 2D This represents the area of ​​the corresponding 2D unit.

[0140] Therefore, to obtain the thickness of the 2D element plane stress element, it is necessary to obtain the volume of the 3D element and the area of ​​the 2D element. The calculation methods for the volume of the 3D element and the area of ​​the 2D element are as follows.

[0141] 1) Calculation of 2D unit area:

[0142] Figure 9 The diagram shows a rectangular element in cylindrical coordinates (r, x). Consider a small area within this plane stress element:

[0143] dA=drdx

[0144] Integrating over the entire element yields the area of ​​that element.

[0145]

[0146] Where x1, x2, r1, and r2 are the coordinate ranges of the rectangular unit.

[0147] However, the shape of a 2D unit is not necessarily... Figure 9 The rectangle shown requires an "isoparametric" transformation in actual calculations, such as... Figure 10 As shown.

[0148] An 8-node quadrilateral element is called an isoparametric element, or simply isoparametric element. Figure 10 This diagram illustrates the transformation of an 8-node element from local coordinates to global coordinates via isoparametric transformation. The local coordinates are located at the center of a square and range from -1 to 1. Let the coordinates at each element node be r. i x i Then the coordinates of any point within the unit are:

[0149]

[0150]

[0151] Where, N i Let be a shape function, which is a function of the local coordinates (η, ξ), and we have:

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160] That is, the formula for calculating the area of ​​a 2D unit:

[0161]

[0162]

[0163] in:

[0164]

[0165]

[0166]

[0167]

[0168] In the formula, The partial derivatives of equation (9) with respect to ξ and η are obtained respectively; the integral of equation (11) is performed in local coordinates, and the readily available "Gaussian numerical integration" method is used for the integral calculation.

[0169] 2) 3D unit volume calculation

[0170] The volume calculation of 3D elements is similar to the area calculation of 2D elements, but with the addition of an additional dimension. A 20-node hexahedral element is called an isoparametric element, or simply isoparametric element. Figure 11 This diagram illustrates the transformation of a 20-node volume element from local coordinates to global rectangular coordinates via isoparametric transformation. The local coordinates are located at the center of the cube, and their values ​​range from (-1, 1). The coordinate transformation formula is as follows:

[0171]

[0172]

[0173]

[0174] For corner points:

[0175] i = 1, 2, 3, 4, 5, 6, 7, 8 where ξ i ,η i ,ζ i Let i be the coordinates of the corner node.

[0176] Nodes in opposite edges:

[0177]

[0178]

[0179]

[0180] Where (x) i y i , z i ) represents the node coordinates of the element, N i This is a shape function.

[0181] That is, the formula for calculating the volume of a 3D unit:

[0182]

[0183] in:

[0184]

[0185]

[0186]

[0187]

[0188] In the formula, u represents x, y, z, and y respectively. The partial derivatives of equation (12) with respect to ξ, η, and ζ are obtained respectively.

[0189] This invention provides a method for converting a blade's 20-node hexahedral solid element mesh into an 8-node quadrilateral planar stress element mesh, facilitating 2D strength calculations for aero-engine rotors.

[0190] Corresponding to the embodiments of the above methods, the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described method for converting plane stress element meshes for engine rotor blades.

[0191] Furthermore, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method for converting plane stress element meshes for engine rotor blades.

[0192] The following describes an engine rotor blade planar stress element mesh conversion system disclosed in an embodiment of the present invention. The engine rotor blade planar stress element mesh conversion system described below can be referred to in correspondence with the engine rotor blade planar stress element mesh conversion method described above.

[0193] This invention also provides a plane stress element mesh conversion system for engine rotor blades, comprising:

[0194] The array setting module is used to set the 3D cell array and the 2D cell array. It inputs the node number of each 3D cell and saves it in the 3D cell array.

[0195] The 2D unit coordinate calculation module is used to traverse the node numbers of all units in all layers of the 3D unit to obtain the node number of the 2D unit, and calculate the coordinate value of the node number of the 2D unit.

[0196] The 2D unit node numbering module is used to calculate the unit node number of the 2D unit based on the overall 2D node number and store it in the 2D unit array.

[0197] The calculation module is used to traverse the nodes of all units in all layers of the 3D unit, calculate the volume of the 3D unit, and traverse the nodes of the 2D unit to calculate the area of ​​the 2D unit; and calculate the thickness of the 2D unit based on the volume of the 3D unit and the area of ​​the 2D unit.

[0198] The 2D unit information output module is used to output the node coordinates and unit information of the 2D unit.

[0199] The engine rotor blade plane stress element mesh conversion system of this embodiment is used to implement the aforementioned engine rotor blade plane stress element mesh conversion method. Therefore, the specific implementation of this system can be found in the embodiment section of the engine rotor blade plane stress element mesh conversion method above. Thus, its specific implementation can be referred to the description of the corresponding embodiments, and will not be elaborated here.

[0200] Furthermore, since the engine rotor blade planar stress element mesh conversion system of this embodiment is used to implement the aforementioned engine rotor blade planar stress element mesh conversion method, its function corresponds to the function of the above method, and will not be repeated here.

[0201] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0202] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 Computer devices that specify the functions in one or more boxes.

[0203] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including an instruction computer device, which is implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0204] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0205] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for converting plane stress element meshes for engine rotor blades, characterized in that: Includes the following steps: S1: Set up the 3D cell array and the 2D cell array, input the node number of each 3D cell and save it in the 3D cell array; S2: Traverse the node numbers of all cells in all layers of the 3D cell to obtain the node numbers of the 2D cell, and calculate the coordinate values ​​of the node numbers of the 2D cell; The method for calculating the coordinate values ​​of the 2D element node number is as follows: The node coordinates of the 2D element obtained by traversing the node numbers of all elements in all layers of the 3D element are still Cartesian coordinates in space. The Cartesian coordinates of the nodes are converted to cylindrical coordinates using the following formula: ， ， in,( , ) represents the cylindrical coordinates of the node. Represents the rectangular coordinates of the nodes; S3: Calculate the element node number of the 2D element based on the overall 2D node number and store it in the 2D element array; S4: Traverse all nodes of all cells in all layers of the 3D cell, calculate the volume of the 3D cell, and traverse all nodes of the 2D cell, calculate the area of ​​the 2D cell. A method for calculating the volume of a 3D element by traversing the nodes of all elements in all layers of the 3D element includes: The nodes of the 3D unit are transformed from local coordinates to global Cartesian coordinates using isoparametric transformation, with the local coordinates located at the center of the cube. The coordinate transformation formula is as follows: ， ， ； in, Let (ξ, η, ζ) represent the rectangular coordinates of the nodes, and (ζ, η, ζ) represent the local coordinates. i Represents a shape function; The volume of a 3D element is calculated based on the local coordinates (ξ, η, ζ) of the node, using the following formula: ， in: ; A method for traversing all nodes in the 2D cell and calculating the area of ​​the 2D cell includes: The nodes of the 2D unit are transformed from local coordinates to global Cartesian coordinates using an isoparametric transformation. The local coordinates are located at the center of the square. The coordinate transformation formula is as follows: ， ； in,( , () represents the cylindrical coordinates of the nodes, (ξ, η) represents the local coordinates, and N represents the local coordinates. i Represents a shape function; The area of ​​a 2D element is calculated based on the local coordinates (ξ, η) of the node, using the following formula: ， in: ， ， ， ， ； S5: Calculate the thickness of the 2D unit based on the volume of the 3D unit and the area of ​​the 2D unit; The formula for calculating the thickness of the 2D unit is: ， in, The volume of the 3D unit. The area of ​​the corresponding 2D unit is N, and the number of blades is N. S6: Output the node coordinates and element information of the 2D element.

2. The method for converting plane stress element meshes for engine rotor blades according to claim 1, characterized in that: In step S2, the method of obtaining the node number of the 2D unit by traversing the node numbers of all units in all layers of the 3D unit includes: The sorting method of the 3D units is specified to be the same as that of the 2D units, wherein the sorting method is to arrange them from left to right first, and then from bottom to top. Let the number of elements in each layer be NC, and the total number of layers be NL. Let i = 1, 2, ..., NL be the layer numbers from bottom to top, j = 1, 2, ..., NC be the sorting numbers of the elements in each layer from left to right, and L be the 2D element node number. Then we have: For 3D element local node number 12: L = (i-1)(3NC+2) + 2(j-1) + 1; For the local node numbers 9 and 11 of the 3D element, we have: L = (i-1)(3NC+2) + 2(j-1) + 2; For the local node numbers 17 and 20 of the 3D element, we have: L = (i-1)(3NC+2) + 2NC + j + 1; When i=1, and j increases from 1 to j=NC, nodes 1 to 12 and nodes 14 to 19 are obtained. Then, j=NC+1 is set to obtain nodes 13 and 20. At this point, all nodes 1 to 20 of the first layer are obtained. Then, all node numbers of the remaining layers are obtained.

3. The method for converting plane stress element meshes for engine rotor blades according to claim 2, characterized in that: In step S3, the method for calculating the element node number of the 2D element based on the overall 2D node number and storing it in the 2D element array includes: Let the 2D cell array be E2d[][], then we have: Ie = i × NC + j, E2d[Ie][1]=(i-1)(3NC+2)+2(j-1)+1, E2d[Ie][2]=E2d[Ie][1]+2, E2d[Ie][5]=E2d[Ie][1]+1, E2d[Ie][8]=(i-1)(3NC+2)+2NC+j+1, E2d[Ie][6]=E2d[Ie][8]+1, E2d[Ie][4]=E2d[Ie][1]+3NC+2, E2d[Ie][3]=E2d[Ie][4]-2, E2d[Ie][7]=E2d[Ie][4]-1; Where i = 1, 2, ..., NL, j = 1, 2, ..., NC, and Ie is the unit number.

4. A plane stress element mesh conversion system for engine rotor blades, characterized in that: include: The array setting module is used to set the 3D cell array and the 2D cell array. It inputs the node number of each 3D cell and saves it in the 3D cell array. The 2D unit coordinate calculation module is used to traverse the node numbers of all units in all layers of the 3D unit to obtain the node number of the 2D unit, and calculate the coordinate value of the node number of the 2D unit. The method for calculating the coordinate values ​​of the 2D element node number is as follows: The node coordinates of the 2D element obtained by traversing the node numbers of all elements in all layers of the 3D element are still Cartesian coordinates in space. The Cartesian coordinates of the nodes are converted to cylindrical coordinates using the following formula: ， ， in,( , ) represents the cylindrical coordinates of the node. Represents the rectangular coordinates of the nodes; The 2D unit node numbering module is used to calculate the 2D unit node number based on the coordinate value of the 2D overall node number and store it in the 2D unit array. The calculation module is used to traverse the nodes of all units in all layers of the 3D unit, calculate the volume of the 3D unit, and traverse the nodes of the 2D unit to calculate the area of ​​the 2D unit; and calculate the thickness of the 2D unit based on the volume of the 3D unit and the area of ​​the 2D unit. A method for calculating the volume of a 3D element by traversing the nodes of all elements in all layers of the 3D element includes: The nodes of the 3D unit are transformed from local coordinates to global Cartesian coordinates using isoparametric transformation, with the local coordinates located at the center of the cube. The coordinate transformation formula is as follows: ， ， ； in, Let (ξ, η, ζ) represent the rectangular coordinates of the nodes, and (ζ, η, ζ) represent the local coordinates. i Represents a shape function; The volume of a 3D element is calculated based on the local coordinates (ξ, η, ζ) of the node, using the following formula: ， in: ; A method for traversing all nodes in the 2D cell and calculating the area of ​​the 2D cell includes: The nodes of the 2D unit are transformed from local coordinates to global Cartesian coordinates using an isoparametric transformation. The local coordinates are located at the center of the square. The coordinate transformation formula is as follows: ， ； in,( , () represents the cylindrical coordinates of the nodes, (ξ, η) represents the local coordinates, and N represents the local coordinates. i Represents a shape function; The area of ​​a 2D element is calculated based on the local coordinates (ξ, η) of the node, using the following formula: ， in: ， ， ， ， ； The formula for calculating the thickness of the 2D unit is: ， in, The volume of the 3D unit. The area of ​​the corresponding 2D unit is N, and the number of blades is N. The 2D unit information output module is used to output the node coordinates and unit information of the 2D unit.

5. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method for converting plane stress element meshes for engine rotor blades as described in any one of claims 1 to 3.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method for converting plane stress element meshes for engine rotor blades as described in any one of claims 1 to 3.

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