Method for determining potential fracture part of cylindrical surface of wheel disc based on two-dimensional finite element

Abstract

The invention discloses a method for determining a potential fracture part of a cylindrical surface of a wheel disc based on a two-dimensional finite element. The method comprises the following steps: partition processing: dividing a two-dimensional calculation model of the wheel disc into an S region, an S1 region and an S2 region; model import and parameter definition: importing the two-dimensional model of the wheel disc into finite element software, and defining material performance parameters of the wheel disc; grid division: performing grid division on the wheel disc, specifying the grid type of the wheel disc, and setting the unit size; setting boundary conditions: setting and calculating the boundary conditions according to the rotating speed, the blade centrifugal force, the wheel disc temperature and the constraint mode; stress distribution calculation: performing simulation calculation to obtain stress distribution of the wheel disc; result exporting: exporting a centrifugal radial stress data file of the S region; the exported result is calculated through programming, and the disc cylindrical surface fracture part and the centrifugal radial stress value of the disc cylindrical surface fracture part are determined and output. The method provided by the invention can determine the weak part of the wheel disc, and provides a basis for optimization design of the wheel disc.

Description

Technical Field

[0001] The present invention belongs to the field of aero-engines, and particularly relates to a method for determining potential rupture sites on the cylindrical surface of a disk based on two-dimensional finite elements. Background Art

[0002] The disk is a key component in an aero-engine. During the normal acceleration process of an aero-engine, instantaneous over-speed rotation, malfunction of the fuel regulator, and failure of the afterburner can all cause the disk to over-speed and even rupture. Once the disk ruptures, it often leads to catastrophic consequences. Therefore, in addition to ensuring its own performance, the aero-engine disk should have sufficient strength margin to avoid disk rupture. During the preliminary design of the disk, to ensure the safe and reliable operation of the designed disk, strength verification of the disk must be carried out. One of the verification contents is the total strength reserve reflecting the load-bearing capacity of the disk, that is, the rupture speed reserve (nb) commonly referred to. Usually, two failure modes are used to calculate the rupture speed: rupture according to the meridian plane and rupture according to the cylindrical surface. Among them, cylindrical surface rupture refers to the occurrence of cracks, fractures and other damage phenomena in the cylindrical surface part of the disk coaxial with the rotation axis. This phenomenon is caused by radial stress. During strength design, the rupture reserve of the disk cylindrical surface is evaluated by the maximum centrifugal radial stress.

[0003] In the disk scheme design stage, finite element software is often used to perform two-dimensional finite element calculations on the disk to preliminarily evaluate the strength reserve of the disk. Among them, for the rupture reserve of the meridian plane, the average circumferential stress on the meridian section of the disk is currently widely used for calculation, and this value can be directly read through post-processing in the finite element software; the rupture reserve of the cylindrical surface can be approximately obtained from the reserve of the maximum centrifugal radial stress. In the two-dimensional finite element calculation results, when calculating the maximum centrifugal radial stress, a number of cross-sections are selected along the radial direction of the disk at a certain interval, and a path is established on each cross-section and stress averaging is performed according to the path. However, the establishment of the path cannot be parameterized at present, and each path can only correspond to a set of parameters. To obtain the maximum centrifugal radial stress of the disk, the parameters for establishing the path need to be continuously changed, resulting in low work efficiency.

[0004] Chinese Patent No. CN117556676B discloses a method for predicting the bursting speed of a double-web turbine disk based on a two-dimensional finite element model. By partitioning the structure of the double-web turbine disk and based on the two-dimensional finite element simulation model of the double-web turbine disk, high-precision and high-efficiency prediction of the bursting speed of the double-web turbine disk is achieved, while meeting the requirements of engineering for the prediction accuracy and efficiency of the bursting speed of the double-web turbine disk. The CN117556676B patent mainly focuses on calculating the radial bursting reserve (i.e., the cylindrical surface bursting reserve), and its core purpose is to predict the bursting speed of the turbine disk through the finite element model. This technical solution analyzes the stress distribution in different regions, combines material property parameters, evaluates the circumferential, radial, and extrusion bursting speed reserves of the turbine disk under specific working conditions, and thus derives the comprehensive bursting speed, ultimately achieving accurate prediction of the bursting speed of the turbine disk.

[0005] However, when designing the strength of an aeroengine disk, it is necessary to accurately determine the potential weak positions in the disk. To achieve this goal, not only in-depth excavation of the finite element calculation results is required, but also stress data needs to be automatically processed through programming means to quickly locate possible high-stress concentration regions. Summary of the Invention

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A method for determining potential bursting sites on the cylindrical surface of a disk based on two-dimensional finite elements, comprising the following steps:

[0008] Partitioning process: Divide the two-dimensional calculation model of the disk into region S, region S1, and region S2, where region S is the region with the smallest web thickness, region S1 is the region with a larger web thickness and the disk bump region, and region S2 is the hub region;

[0009] Model import and parameter definition: Import the partitioned two-dimensional model of the disk into finite element software and define the material property parameters of the disk;

[0010] Mesh generation: Generate a mesh for the disk. When generating a mesh for region S, specify its mesh type as quadrilateral elements and set the element size;

[0011] Boundary condition setting: Set the calculation boundary conditions according to the rotational speed, blade centrifugal force, disk temperature, and constraint method;

[0012] Stress distribution calculation: Perform simulation calculations to obtain the stress distribution of the disk;

[0013] Result export: Export the centrifugal radial stress data file of region S, and the data file contains node numbers, node coordinates, and corresponding centrifugal radial stress values;

[0014] The program calculates and determines the rupture location: By programming the exported results, the rupture location on the cylindrical surface of the disk and its centrifugal radial stress value are determined and output.

[0015] In the mesh generation step, the mesh generation method for the S region is an eight-node quadrilateral element or a four-node quadrilateral element, and the element size is a preset value.

[0016] In the boundary condition setting step, specifically: Apply the blade centrifugal force at the disk rim, apply the disk centrifugal force through the rotational speed, apply the disk temperature at the disk center, and apply an axial constraint at the front shaft end of the disk.

[0017] In the program calculation to determine the rupture location, the following steps are included:

[0018] Set the storage path of the centrifugal radial stress data file, the element size, and the initial value of the average centrifugal radial stress;

[0019] Read the centrifugal radial stress data file to determine the centrifugal direction radius range [Xmin, Xmax] of the S region;

[0020] Determine the spacing delta between adjacent nodes in the centrifugal direction according to the element size;

[0021] Calculate the number of rows of the element nodes in the centrifugal direction of the S region according to the spacing delta between adjacent nodes in the centrifugal direction;

[0022] Traverse each radius position in the centrifugal direction and calculate the average centrifugal radial stress at each radius;

[0023] Calculate the radius position and the corresponding average stress of each row in turn through a loop, and update the maximum stress value and the corresponding radius;

[0024] Determine and output the centrifugal radial stress value on the cylindrical surface and its rupture location according to the result of comparing the average stress values at each radius through the loop.

[0025] The method for determining the spacing delta between adjacent nodes is:

[0026] When the mesh of the S region is an eight-node quadrilateral element, delta = 0.5 × element size;

[0027] When the mesh of the S region is a four-node quadrilateral element, delta = element size.

[0028] The output result of the program calculation to determine the rupture location is the maximum average centrifugal radial stress value and the corresponding rupture location radius coordinate.

[0029] The beneficial effects of the present invention are:

[0030] The design of the disk structure is an iterative process. Every change in the disk structure, material, load, etc. is accompanied by a large amount of strength checking work. Therefore, the present invention proposes a method for determining the potential rupture sites on the cylindrical surface of the disk based on two-dimensional finite elements to determine the weak parts of the disk, so as to provide a basis for the optimization design of the disk.

[0031] Compared with the existing methods for judging the weak parts of the disk, the present invention exports the finite element calculation results and combines programming means for automatic processing, avoiding the low efficiency problem of relying on manual point-by-point search for rupture sites in the traditional methods, greatly improving the work efficiency. This technical solution can help designers discover and solve potential structural hidden dangers in advance, and improve the overall safety and reliability of the turbine disk. By reasonably partitioning the disk model and performing refined stress analysis on key areas (such as the area with the smallest web thickness), the weak parts of the disk can be more accurately located, providing a reliable basis for design optimization. The method provided by the present invention has clear and definite steps, which are convenient for engineering and technical personnel to master and implement. At the same time, it reduces the dependence on complex experimental equipment and lowers the R & D cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic flow diagram of the method for determining the potential rupture sites on the cylindrical surface of the disk based on two-dimensional finite elements;

[0033] Figure 2 is a schematic diagram of the partition of the two-dimensional disk model;

[0034] Figure 3 is a two-dimensional finite element model of a certain high-pressure compressor rotor;

[0035] Figure 4 is a two-dimensional geometric model and finite element model of a certain three-stage disk;

[0036] Figure 5 is a schematic flow diagram of the calculation process for determining the rupture sites on the cylindrical surface of the disk;

[0037] Figure 6 is a comparison of the calculation results for determining the rupture sites on the cylindrical surface of the disk. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following describes the embodiments of the present application in detail with reference to the drawings.

[0039] As Figure 1 shown, the present invention provides a method for determining the potential rupture sites on the cylindrical surface of the disk based on two-dimensional finite elements. This method runs in the activated Workbench environment and includes the following steps:

[0040] Load the two-dimensional calculation model of the disk;

[0041] Partition processing: As Figure 2As shown in the figure, the two-dimensional calculation model of the wheel disc is divided into region S, region S1, and region S2, where region S is the region with the minimum web thickness, region S1 is the region with a larger web thickness and the wheel disc bump region, and region S2 is the hub region.

[0042] Model import and parameter definition: Import the partitioned two-dimensional model of the wheel disc into the finite element software and define the material property parameters of the wheel disc.

[0043] Mesh generation: Generate a mesh for the wheel disc. When generating a mesh for region S, specify its mesh type as quadrilateral elements and set the element size to a preset value. Among them, the mesh generation method for region S is eight-node quadrilateral elements or four-node quadrilateral elements.

[0044] Boundary condition setting: Set the calculation boundary conditions according to the rotational speed, blade centrifugal force, wheel disc temperature, and constraint method. Apply the blade centrifugal force to the rim of each stage of the wheel disc. The wheel disc centrifugal force is applied through the rotational speed. Apply the wheel disc temperature to the center of the rim of each stage of the disc. Apply an axial constraint to the front end of the front axle in Figure 3 the front axle.

[0045] Stress distribution calculation: Perform a simulation calculation to obtain the stress distribution of the wheel disc.

[0046] Result export: Export the centrifugal radial stress data file for region S. The data file contains the node numbers, node coordinates, and the corresponding centrifugal radial stress values.

[0047] Program calculation to determine the rupture location: Calculate the exported results through programming to determine the rupture location on the cylindrical surface of the wheel disc and its centrifugal radial stress value. Specifically, it includes:

[0048] Set the storage path of the centrifugal radial stress file, the unit size, and the initial value of the average centrifugal radial stress.

[0049] Read the centrifugal radial stress data file to determine the centrifugal direction radius range [Xmin, Xmax] of region S.

[0050] Determine the spacing delta between adjacent nodes in the centrifugal direction according to the unit size. The determination method is as follows: When the mesh of region S is eight-node quadrilateral elements, delta = 0.5 × unit size; when the mesh of region S is four-node quadrilateral elements, delta = unit size.

[0051] Calculate the number of rows of the unit nodes in the centrifugal direction of region S according to the spacing delta between adjacent nodes in the centrifugal direction.

[0052] Traverse each radius position in the centrifugal direction and calculate the average centrifugal radial stress at each radius.

[0053] Calculate the radius positions and corresponding average stresses of each row in sequence through a loop, and update the maximum stress value and the corresponding radius.

[0054] According to the result of comparing the average stress values at each radius through the loop, determine and output the centrifugal radial stress value of the cylindrical surface and its rupture location, and the output result is the maximum average centrifugal radial stress value and the corresponding radius coordinate of the rupture location.

[0055] Based on the above method, specific embodiments are proposed, and the implementation steps are as follows:

[0056] Step S1: As Figure 3 shown, when calculating the stress distribution of a certain high-pressure compressor rotor, take the third-stage disk of a certain high-pressure compressor as an example, use UG software to partition the two-dimensional model of the third-stage disk, and do not process the other disks. After partitioning, the geometric model of the third-stage disk is as Figure 4 shown.

[0057] Step S2: Import the two-dimensional calculation model in UG software into the finite element software Workbench, and define the material property parameters of the disk. Among them, the materials of the first to eighth stages of the high-pressure compressor disks are all titanium alloys, the material of the rear seal labyrinth disk is a superalloy, and the materials of the front shaft and rear shaft are stainless steels. Their material parameters can be found in the corresponding manuals.

[0058] Step S3: Mesh the high-pressure compressor rotor. When meshing the S area of the third-stage disk, set the element size to 1 mm and specify the mesh generation method for the S area as quadrilateral. The finite element model of the third-stage disk is as Figure 4 shown.

[0059] Step S4: Set the calculation boundary conditions according to the rotational speed, blade centrifugal force, disk temperature, and constraint method; specifically: Apply the blade centrifugal force at the rim of each stage disk, the disk centrifugal force is applied through the rotational speed, apply the temperature at the center of the rim of each stage disk, and apply an axial constraint at the front end of the front shaft in Figure 3 .

[0060] Step S5: Obtain the stress distribution of the disk through simulation calculation.

[0061] Step S6: In the output settings of Workbench, set the node number and node coordinates to "Yes", and export the centrifugal radial stress result of the S area of the third-stage disk as "3ji.txt". The exported file contains the nodes, coordinates, and their corresponding stress values.

[0062] Step S7: Calculate the exported results through programming to determine the rupture location of the disk cylindrical surface and its centrifugal radial stress value. As Figure 5 shown, it specifically includes:

[0063] Step S701: setting the centrifugal radial stress file storage path filePath, the unit size E_size and the average centrifugal radial stress initial value aver_sx, where the unit size is consistent with the S region in step S3;

[0064] Step S702: Read the centrifugal radial stress file parameters and calculate the radius range [Xmin, Xmax] of the wheel disc S region in the centrifugal direction;

[0065] Step S703: Calculate the number of rows n_row of the S region centrifugal direction unit nodes according to the distance delta between adjacent nodes in the centrifugal direction; in particular, the S region unit in step S3 is an eight-node quadrilateral unit, so delta=0.5*E_size.

[0066] Step S704: Calculate the radius corresponding to the node in the i-th row, x=Xmin+(i-1)*delta;

[0067] Step S705: Calculate the average centrifugal radial stress aver at radius x;

[0068] Step S706: Compare aver with aver_sx (initial value is 0), when aver>aver_sx, assign it to aver_sx, and assign its radius x to x_;

[0069] Step S707: Steps S704 to S706 are implemented through a loop command. After the loop is executed, the centrifugal radial stress value aver_sx of the cylindrical surface and its rupture location x_ are output. The output result is the maximum average centrifugal radial stress value and the corresponding radius coordinate of the rupture location. The calculation result comparison is as follows: Figure 6 .

[0070] The method for determining the potential rupture sites of the cylindrical surface of a wheel based on two-dimensional finite elements proposed in the present invention can quickly determine the weak sites of the wheel through program calculation after exporting the centrifugal radial stress results, avoiding the traditional method of relying on manpower to find the rupture sites, thereby improving work efficiency and providing a basis for the optimal design of the wheel.

[0071] The above description is only a specific embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications, improvements or variations can be made to the above embodiments without departing from the principles of the present invention, and these modifications, improvements or variations should all be included in the protection scope of the present invention.

Claims

1. A method for determining potential rupture locations of a wheel disc cylindrical surface based on two-dimensional finite elements, characterized in that: The following steps are involved: Partition processing: The two-dimensional calculation model of the wheel is divided into S area, S1 area and S2 area, where S area is the area with the smallest spoke thickness, S1 area is the area with large spoke thickness and wheel bumps, and S2 area is the hub area; Model import and parameter definition: import the partitioned roulette two-dimensional model into the finite element software and define the roulette material performance parameters; Meshing: Mesh the wheel. When meshing the S region, specify the mesh type as quadrilateral element and set the element size. Boundary condition setting: Set the calculation boundary conditions according to the rotation speed, blade centrifugal force, disk temperature and constraint method; Stress distribution calculation: Perform simulation calculation to obtain the stress distribution of the wheel; Result export: export the centrifugal radial stress data file of the S region, the data file includes the node number, node coordinates and the corresponding centrifugal radial stress value; The program calculates and determines the rupture location: The derived results are calculated through programming to determine and output the rupture location of the wheel cylindrical surface and its centrifugal radial stress value.

2. The method according to claim 1, characterized in that In the meshing step, the meshing method for the S region is eight-node quadrilateral units or four-node quadrilateral units, and the unit size is a preset value.

3. The method according to claim 1, characterized in that The boundary condition setting step specifically includes: applying blade centrifugal force to the wheel rim, applying wheel centrifugal force through the rotation speed, applying wheel temperature at the wheel center, and applying axial constraint at the front shaft end of the wheel.

4. The method according to claim 1, characterized in that The program calculates and determines the rupture site, including the following steps: Set the centrifugal radial stress data file storage path, unit size and average centrifugal radial stress initial value; Read the centrifugal radial stress data file to determine the centrifugal direction radius range [Xmin, Xmax] of the S region; Determine the distance delta between adjacent nodes in the centrifugal direction according to the unit size; According to the distance delta between adjacent nodes in the centrifugal direction, the number of rows of unit nodes in the centrifugal direction of region S is calculated; Traverse each radial position in the centrifugal direction and calculate the average centrifugal radial stress at each radius; The radius position and the corresponding average stress of each row are calculated in turn through a loop, and the maximum stress value and the corresponding radius are updated; Based on the results of cyclic comparison of the average stress values ​​at each radius, the centrifugal radial stress value of the cylindrical surface and its rupture location are determined and output.

5. The method according to claim 1, characterized in that The method for determining the distance delta between adjacent nodes is: When the S region mesh is an eight-node quadrilateral element, delta = 0.5 × element size; When the S-region mesh is a four-node quadrilateral element, delta = element size.

6. The method according to claim 1, characterized in that The output result of the program calculation to determine the rupture site is the maximum average centrifugal radial stress value and the corresponding radius coordinate of the rupture site.

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