A parameter control method and system for improving low cycle fatigue life of a wheel disc

Abstract

The application discloses a parameter control method and system for improving low-cycle fatigue life of a wheel disc, and belongs to the technical field of engine part strength improvement. The method comprises obtaining optimized pre-rotation parameters and optimized secondary strengthening treatment parameters based on finite element calculation. First residual stress distribution and first deformation of the wheel disc under different pre-rotation parameters are calculated through the finite element calculation, and stress state calculation of the wheel disc under working rotation parameters is carried out based on the first residual stress distribution and the first deformation of the wheel disc. The optimized pre-rotation parameters can be selected based on the stress state of the wheel disc, and the wheel disc treated under the optimized pre-rotation parameters is used as the selection basis of the subsequent secondary strengthening treatment parameters, so that the finite element calculation of the subsequent secondary strengthening treatment parameters is carried out, and the rationality of the selection of the subsequent secondary strengthening treatment parameters is ensured.

Description

Technical Field

[0001] This application belongs to the field of engine component strength improvement technology, specifically relating to a parameter control method and system for improving the low-cycle fatigue life of a wheel disc. Background Technology

[0002] The turbine disc is a critical component in an aero-engine; its failure directly impacts safety and maintenance costs, and can even jeopardize flight safety. The main functions of the turbine disc are to fix the blades, transmit the thrust generated by the high-pressure gas flow through the blades, and withstand the centrifugal force from the blades. It includes various types such as fan discs, compressor discs, turbine discs, guide vanes, drum-shaped discs, and grate discs. As a primary load-bearing component, the aero-engine turbine disc withstands the combined effects of centrifugal force, thermal stress, and vibration stress during operation. Once it ruptures, it is highly likely to cause non-containment failure, potentially penetrating the engine casing and cutting off fuel lines or control systems, or penetrating the fuel tank or cockpit, leading to a catastrophic accident.

[0003] According to statistical analysis, low-cycle fatigue failure is one of the most serious problems faced by wheel disks during service. Existing methods to improve the low-cycle fatigue life of wheel disks mainly include: (1) thickening the wheel disk to improve the structural strength of high-stress areas, thereby improving the low-cycle fatigue life of the wheel disk; (2) strengthening the surface of the wheel disk, such as mechanical shot peening, laser shock strengthening, pre-rotation, etc. Through these methods, uneven plastic deformation is introduced on the surface of the wheel disk, thereby forming a high-amplitude residual compressive stress layer, improving the surface strength of the wheel disk, inhibiting fatigue crack propagation, and thus significantly improving the low-cycle fatigue life of the wheel disk.

[0004] Based on a well-designed turbine disc structure, strengthening methods can further extend the fatigue life of the disc. Prestressing technology is one effective method, first applied to gas turbines. General Electric used this technology to effectively prevent similar accidents after gas turbine explosions. Soviet turbine factories also applied this technology to produce various types of turbine disc components, significantly reducing the working stress on the disc and allowing the use of steel with better plasticity, resulting in thinner and lighter discs, reducing manufacturing costs by nearly half.

[0005] A turbine disk is a rotating structural component. Pre-rotating the disk is an effective method for achieving prestress strengthening. Its mechanism includes two aspects: first, it induces plastic deformation in the disk as a whole, achieving strain strengthening and increasing the material's yield strength, thereby suppressing deformation that may occur under normal operating loads; second, it generates residual compressive stress in local high-stress areas of the disk, thereby reducing the cyclic average stress in these areas during service and extending fatigue life. Therefore, pre-rotating aero-engine disks can strengthen them, thereby reducing their overall structural dimensions. This is expected to achieve longer disk lifespan, lighter design, and reduced manufacturing costs, which is of great significance for improving aero-engine performance. However, due to the different structural characteristics and materials of disks, the residual stress distribution characteristics generated by pre-rotation vary. Therefore, the pre-rotation process parameters are difficult to select, the process debugging cycle is long and costly, and the disk structure is complex. In some areas, after pre-rotation, there may be intersection zones of residual compressive and residual tensile stresses, which can become crack initiations for fatigue failure under operating conditions. This makes controlling the pre-rotation process parameters and subsequent strengthening treatment parameters quite difficult.

[0006] Application content

[0007] The purpose of this application is to provide a parameter control method for improving the low-cycle fatigue life of a wheel, so as to solve the problem of difficulty in controlling the existing wheel pre-rotation process parameters and secondary strengthening treatment parameters as mentioned in the background art.

[0008] To achieve the above objectives, this application provides the following technical solution: a parameter control method for improving the low-cycle fatigue life of a rotary disk, comprising:

[0009] Finite element analysis was used to obtain the first residual stress distribution and deformation of the disk under different pre-rotation parameters.

[0010] Using the first residual stress distribution and deformation of the disk as the finite element input conditions, the stress state of the disk under the working rotation parameters is calculated.

[0011] The low-cycle fatigue life of the disk under different pre-rotation parameters is calculated based on the stress state of the disk, and the corresponding pre-rotation parameters that meet the low-cycle fatigue life requirements are output as optimized pre-rotation parameters.

[0012] Using the first residual stress distribution and deformation of the disk under optimized pre-rotation parameters as the finite element input conditions, the disk is subjected to secondary strengthening treatment. The second residual stress distribution and deformation of the disk under different secondary strengthening treatment parameters are obtained by finite element calculation, and the corresponding secondary strengthening parameters that meet the requirements of the second residual stress distribution and deformation are output as the optimized secondary strengthening treatment parameters.

[0013] Furthermore, the pre-rotation parameters include rotational speed, temperature, and rotation time.

[0014] Furthermore, based on the stress state calculation of the disk, the low-cycle fatigue life of the disk under different pre-rotation parameters is obtained as follows:

[0015] Obtain the stress in the critical direction at the stress concentration location of the wheel disk, and calculate the low-cycle fatigue life based on the stress in the critical direction.

[0016] Furthermore, the stress in the dangerous direction is a circumferential stress, radial stress, axial stress, or the first principal stress.

[0017] Furthermore, secondary strengthening treatments for the wheel include shot peening, laser shock peening, or roll forming.

[0018] Furthermore, when performing secondary strengthening treatment on the wheel, the secondary strengthening treatment area of ​​the wheel is the surface of the wheel that has residual tensile stress after pre-rotation.

[0019] Furthermore, the method also includes verifying the second residual stress distribution and deformation amount under the optimized secondary strengthening treatment parameters obtained by finite element calculation through experiments.

[0020] Furthermore, the optimized secondary strengthening parameters that meet the second deformation requirement indicate that the second deformation of the disk under these secondary strengthening parameters, obtained by finite element calculation, meets the tolerance requirements.

[0021] Furthermore, the method also includes: adjusting the wheel processing steps based on the first deformation of the wheel under optimized pre-rotation parameters calculated by finite element method.

[0022] Another aspect of this application discloses a parameter control system for improving the low-cycle fatigue life of a roulette wheel, comprising:

[0023] The first calculation module is configured to use finite element calculation to obtain the first residual stress distribution and deformation of the disk under different pre-rotation parameters.

[0024] The second calculation module is configured to use the first residual stress distribution and deformation of the disk as finite element input conditions to calculate the stress state of the disk under working rotation parameters.

[0025] The first output module is configured to calculate the low-cycle fatigue life of the disk under different pre-rotation parameter conditions based on the stress state of the disk, and output the pre-rotation parameters that meet the low-cycle fatigue life requirements as optimized pre-rotation parameters.

[0026] The second output module is configured to use the first residual stress distribution and deformation of the disk under optimized pre-rotation parameters as finite element input conditions to perform secondary strengthening treatment on the disk. The finite element calculation obtains the second residual stress distribution and deformation of the disk under different secondary strengthening treatment parameters, and outputs the secondary strengthening parameters that meet the requirements of the second residual stress distribution and deformation as optimized secondary strengthening treatment parameters.

[0027] Compared with the prior art, the beneficial effects of this application are:

[0028] This application uses finite element analysis to calculate the first residual stress distribution and first deformation of the disk under different pre-rotation parameters. Based on the first residual stress distribution and first deformation of the disk, it calculates the stress state of the disk under the working rotation parameters. This allows for the selection of optimized pre-rotation parameters based on the stress state of the disk. The disk after optimization of the pre-rotation parameters is used as the basis for selecting the parameters for subsequent secondary strengthening treatment, and finite element analysis is performed on the parameters for subsequent secondary strengthening treatment, ensuring the rationality of the selection of the parameters for subsequent secondary strengthening treatment. Attached Figure Description

[0029] Figure 1 This is a flowchart of the method in this application;

[0030] Figures 2a-2c The residual equivalent stress distribution of the disk after processing with different pre-rotation parameters;

[0031] Figures 3a-3c Equivalent stress distribution of the disk at operating speed after processing with different pre-rotation parameters;

[0032] Figure 4a and 4b This is a simulation analysis diagram of shot peening strengthening of the tenon and groove structure. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] A parameter control method for improving the low-cycle fatigue life of a rotary disk, referring to... Figure 1 ,include;

[0035] S100: Finite element calculations yielded the first residual stress distribution and first deformation of the disk under different pre-rotation parameters;

[0036] S200: Using the first residual stress distribution and deformation of the disk as finite element input conditions, the stress state of the disk under working rotation parameters is calculated.

[0037] S300: Based on the stress state calculation of the disk, the low-cycle fatigue life of the disk under different pre-rotation parameters is obtained, and the corresponding pre-rotation parameters that meet the low-cycle fatigue life requirements are output as optimized pre-rotation parameters.

[0038] S400: Using the first residual stress distribution and deformation of the disk under optimized pre-rotation parameters as finite element input conditions, the disk is subjected to secondary strengthening treatment. Finite element calculations obtain the second residual stress distribution and second deformation of the disk under different secondary strengthening treatment parameters, and output the secondary strengthening parameters that meet the requirements of the second residual stress distribution and second deformation as optimized secondary strengthening treatment parameters.

[0039] Specifically, in step S100, the pre-rotation parameters include rotational speed, temperature, and rotation time. When calculating the first residual stress distribution and first deformation of the disk under different pre-rotation parameter conditions using finite element analysis, the rotational speed is used as the input load, for example, by inputting the rotational speed through the Rotational Velocity command in ANSYS. The temperature is used as the boundary condition input. At the same time, when performing finite element analysis on the disk, the corresponding geometric model and material property parameters of the disk also need to be input. The material property parameters include material density, elastic modulus, Poisson's ratio, plastic constitutive parameters, and coefficient of thermal expansion at a set temperature (e.g., the temperature under working conditions).

[0040] Meanwhile, in step S100, the deformation of the wheel is the deformation of the unit at the location where plastic deformation occurs in the wheel.

[0041] In step S200, the first residual stress distribution and deformation of the disk are used as finite element input conditions, and calculations are performed. This means that when performing finite element calculations, the first residual stress distribution and deformation of the disk need to be used as boundary conditions, and combined with other input conditions, such as the aforementioned rotational speed input and disk model input, to complete the finite element calculation. Specifically, in steps S100 and S200, after changing different pre-rotation parameters for calculation, the rotational speed is reduced to 0 to complete the unloading from rotation. Then, the disk is accelerated to the working rotational speed to obtain the stress state under working conditions. At the same time, when performing finite element calculations of the stress state of the disk under working rotational parameters, the input temperature boundary condition is the temperature of the disk under working conditions.

[0042] In step S300, the low-cycle fatigue life of the disk under different pre-rotation parameters is calculated based on the stress state of the disk, including:

[0043] Obtain the stress in the critical direction at the stress concentration location of the wheel disk, and calculate the low-cycle fatigue life based on the stress in the critical direction.

[0044] Specifically, the aforementioned dangerous direction stresses include, but are not limited to, circumferential stress, radial stress, axial stress, or the first principal stress. The criterion for judging dangerous direction stresses is that the stress component in that direction is tensile stress and the stress value is the largest. After obtaining the dangerous direction stresses of the wheel, the low-cycle fatigue life can be calculated based on the dangerous direction stresses at the concentrated location of the wheel using the Manson-Coffin formula (Equation 1 below), the Morrow elastic stress correction model, the SWT parameter prediction model, the Walker correction model, etc.

[0045]

[0046] Where, ε a Where σ is the strain amplitude, N is the fatigue life, and σ is the fatigue amplitude. f ′ ε f ′ b, c are fatigue strength coefficient, fatigue ductility coefficient, fatigue strength index, and fatigue ductility index, respectively, and E is the elastic modulus.

[0047] Meanwhile, in step S300, meeting the low-cycle fatigue life requirement indicates that the low-cycle fatigue life of the wheel meets the expected target.

[0048] In step S400, the secondary strengthening treatment of the wheel includes, but is not limited to, shot peening, laser shock peening and rolling. When performing secondary strengthening treatment on the wheel, the selection can be based on the first residual stress distribution of the wheel to reduce the subsequent adjustment process. That is, the secondary strengthening treatment area of ​​the wheel is the surface of the wheel with residual tensile stress after pre-rotation.

[0049] Returning to step S400, satisfying the requirements for the second residual stress distribution and the second deformation means that after pre-rotation and secondary strengthening treatment, the radial residual tensile stress in the first residual stress distribution is manifested as radial residual compressive stress in the second residual stress distribution, and the depth and value of the residual compressive stress layer in the second residual stress distribution are not reduced compared to the depth and value of the residual compressive stress layer in the first residual stress distribution. At the same time, the second deformation of the wheel does not exceed the tolerance requirements of the drawing.

[0050] In some embodiments, the above method further includes verifying the second residual stress distribution and deformation under the optimized secondary strengthening treatment parameters obtained by finite element calculation through experiments. That is, conducting a physical test of the wheel based on the optimized pre-rotation parameters and the optimized secondary strengthening treatment parameters, and verifying the data obtained by finite element calculation by comparing the physical test data and the data obtained by finite element calculation. In other examples, the above data comparison verification also includes the comparison verification of low-cycle fatigue life.

[0051] In some embodiments, the above method further includes: adjusting the wheel processing steps based on the first deformation of the wheel under optimized pre-rotation parameters calculated by finite element method.

[0052] Specifically, when the finite element calculation shows that the first deformation of the disk under the optimized pre-rotation parameter conditions does not exceed the specified error range, the disk is first pre-rotated, then the dimensional correction process is performed, and finally the secondary strengthening process is performed.

[0053] The residual stress state generated in the gas turbine disk by the pre-rotation strengthening involved in this application was calculated using the finite element method (e.g., Figures 2a-2c As shown) and the superposition of residual stress generated by pre-rotation and stress at the operating speed (as shown) Figures 3a-3c As shown in the figure, comparison shows that after pre-rotation and over-rotation treatment, the maximum equivalent stress at the wheel center at the operating speed is reduced, which initially indicates that pre-rotation has a certain effect on improving the low-cycle fatigue life of the wheel. At the same time, the finite element analysis results show that as the speed increases, the main dangerous areas of the wheel under rotating conditions are the wheel center and the tenon groove. Shot peening was selected as a secondary strengthening treatment method, and a finite element simulation analysis technology study on the shot peening strengthening process was carried out on the tenon groove structure of the wheel (e.g. Figure 4a and 4b As shown in the figure, the effect of shot peening on the fatigue life of the tenon groove test specimen was preliminarily explored. The test results show that after shot peening, the fatigue life of the tenon groove under low cyclic fatigue load in the range of 100% to 120% is increased by an average of 2.02 times.

[0054] This application utilizes finite element analysis to optimize process parameters, improving the efficiency of developing pre-strain strengthening processes for the wheel disk and reducing experimental costs. Furthermore, it allows for analysis of the stress state under pre-rotation, secondary strengthening treatment, and operating speed, further optimizing the residual stress distribution of the wheel disk, identifying fatigue failure hazard points for reinforcement, and ultimately enhancing the lifespan extension of the pre-rotated wheel disk.

[0055] This application also discloses a parameter control system for improving the low-cycle fatigue life of a wheel, comprising:

[0056] The first calculation module is configured to use finite element calculation to obtain the first residual stress distribution and the first deformation of the disk under different pre-rotation parameters.

[0057] The second calculation module is configured to use the first residual stress distribution and the first deformation of the disk as finite element input conditions to calculate the stress state of the disk under working rotation parameters.

[0058] The first output module is configured to calculate the low-cycle fatigue life of the disk under different pre-rotation parameter conditions based on the stress state of the disk, and output the pre-rotation parameters that meet the low-cycle fatigue life requirements as optimized pre-rotation parameters.

[0059] The second output module is configured to perform secondary strengthening treatment on the disk using the first residual stress distribution and the first deformation amount of the disk under optimized pre-rotation parameters as finite element input conditions. The finite element calculation obtains the second residual stress distribution and the second deformation amount of the disk under different secondary strengthening treatment parameters, and outputs the secondary strengthening parameters that meet the requirements of the second residual stress distribution and the second deformation amount as optimized secondary strengthening treatment parameters.

[0060] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A parameter control method for improving the low cycle fatigue life of a wheel disc, characterized in that, include: Finite element analysis was used to obtain the first residual stress distribution and first deformation of the disk under different pre-rotation parameters. Using the first residual stress distribution and the first deformation of the disk as the finite element input conditions, the stress state of the disk under the working rotation parameters is calculated. The low-cycle fatigue life of the disk under different pre-rotation parameters is calculated based on the stress state of the disk, and the corresponding pre-rotation parameters that meet the low-cycle fatigue life requirements are output as optimized pre-rotation parameters. Using the first residual stress distribution and deformation of the disk under optimized pre-rotation parameters as finite element input conditions, the disk is subjected to secondary strengthening treatment. Finite element calculations obtain the second residual stress distribution and second deformation of the disk under different secondary strengthening treatment parameters, and output the secondary strengthening parameters that meet the requirements of the second residual stress distribution and second deformation as optimized secondary strengthening treatment parameters.

2. The parameter control method for improving the low cycle fatigue life of a wheel disc according to claim 1, characterized in that: The pre-rotation parameters include rotational speed, temperature, and rotation time.

3. The parameter control method for improving the low cycle fatigue life of a wheel disc according to claim 1, characterized in that: The low-cycle fatigue life of the disk under different pre-rotation parameters, calculated based on the stress state of the disk, includes: Obtain the stress in the critical direction at the stress concentration location of the wheel disk, and calculate the low-cycle fatigue life based on the stress in the critical direction.

4. The parameter control method for improving the low cycle fatigue life of a wheel disc according to claim 3, characterized in that: The stress in the dangerous direction is either circumferential stress, radial stress, axial stress, or the first principal stress.

5. The parameter control method for improving the low-cycle fatigue life of a wheel according to claim 1, characterized in that: Secondary strengthening treatments for the rotary disc include shot peening, laser shock peening, or roll forming.

6. The parameter control method for improving the low-cycle fatigue life of a wheel according to claim 1, characterized in that: When performing secondary strengthening treatment on the wheel, the secondary strengthening treatment area is the surface of the wheel that has residual tensile stress after pre-rotation.

7. The parameter control method for improving the low-cycle fatigue life of a wheel according to claim 1, characterized in that: The method also includes verifying the second residual stress distribution and deformation under the optimized secondary strengthening treatment parameters obtained by finite element calculation through experiments.

8. The parameter control method for improving the low-cycle fatigue life of a wheel according to claim 1, characterized in that: The optimized secondary strengthening parameters that meet the second deformation requirement indicate that the second deformation of the disk under these parameters, obtained from finite element analysis, meets the tolerance requirements.

9. The parameter control method for improving the low-cycle fatigue life of a wheel according to claim 1, characterized in that: The method further includes: adjusting the wheel processing steps based on the first deformation of the wheel under optimized pre-rotation parameters calculated by finite element method.

10. A parameter control system for improving the low-cycle fatigue life of a rotary disk, characterized in that, include: The first calculation module is configured to use finite element calculation to obtain the first residual stress distribution and the first deformation of the disk under different pre-rotation parameters. The second calculation module is configured to use the first residual stress distribution and deformation of the disk as finite element input conditions to calculate the stress state of the disk under working rotation parameters. The first output module is configured to calculate the low-cycle fatigue life of the disk under different pre-rotation parameter conditions based on the stress state of the disk, and output the pre-rotation parameters that meet the low-cycle fatigue life requirements as optimized pre-rotation parameters. The second output module is configured to perform secondary strengthening treatment on the disk using the first residual stress distribution and the first deformation amount of the disk under optimized pre-rotation parameters as finite element input conditions. The finite element calculation obtains the second residual stress distribution and the second deformation amount of the disk under different secondary strengthening treatment parameters, and outputs the secondary strengthening parameters that meet the requirements of the second residual stress distribution and the second deformation amount as optimized secondary strengthening treatment parameters.

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