Method for determining service life of wheel disc based on characteristics of multi-notch fatigue sample
By integrating a multi-notch model onto a single fatigue specimen and utilizing finite element analysis and multi-objective optimization algorithms to optimize the notch design, the problems of large errors and high costs in the fatigue life prediction of aero-engine rotor disks in existing technologies have been solved, achieving high-precision and low-cost life prediction.
Patent Information
- Application Number
- CN202511033618.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-25
- Publication Date
- 2025-11-07
AI Technical Summary
Existing technologies fail to effectively consider the stress concentration characteristics of multiple notches when predicting the fatigue life of aero-engine rotor disks, resulting in large prediction errors and high costs. Single-notch specimen design cannot simulate the stress concentration characteristics of multiple notches on rotor disks, further increasing economic costs.
By establishing a geometric model of a multi-notch fatigue specimen and integrating multiple notches onto a single fatigue specimen, the notch radius, depth, and specimen radius are optimized using finite element analysis and multi-objective optimization algorithms. This ensures the consistency of the stress distribution of the specimen with the key parts of the wheel and reduces simulation costs.
This method enables the simulation of multiple notch stress distributions on an aero-engine wheel disk on a single fatigue specimen, reducing the testing cost of fatigue life simulation components and improving prediction accuracy, while ensuring consistency between the notch stress distribution of the specimen and the key parts of the wheel disk.
Smart Images
Figure CN120911201A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of engine health monitoring, in particular, to a method for determining the life of a wheel disc based on the characteristics of a multi-notch fatigue test sample. BACKGROUND
[0002] There are multiple weak life positions in an aero-engine wheel disc, such as the mortise, web transition and air hole in the high-pressure turbine disc. The large stress of these positions is derived from the discontinuity of the material, and different radii of the notches cause different degrees of stress concentration.
[0003] When predicting the fatigue life of the key positions of the wheel disc, the traditional Coffin-Manson model is currently used. Since the supporting effect of the notch is not considered, the predicted fatigue life is too conservative, and there is a large error with the test results. The notch fatigue data in the current material manual is generally based on the stress concentration coefficients K t =2, K t =3 and K t =5 fatigue test results, and the notch radii of the K t =2, K t =3 and K t =5 fatigue test samples are 0.75mm, 0.34mm and 0.14mm respectively. Since the notch radius is small, the stress gradient at the notch is large. The design of such a single-notch test sample has a large difference with the notch stress gradient in the engine wheel disc, and directly using the test results of such a single-notch test sample to predict the fatigue life of the key positions of the engine wheel disc may be dangerous. On the other hand, due to the complexity of the state of the wheel disc, the single-notch test sample design cannot simulate the multi-notch stress concentration characteristics of the aero-engine wheel disc, and designing a simulation piece for fatigue test for each notch greatly increases the economic cost.
[0004] It can be seen that the notch stress gradient in the existing fatigue test sample has a large difference with the key positions of the aero-engine wheel disc, and the cost of designing a simulation piece for fatigue test for each key position of the aero-engine is high. SUMMARY
[0005] To solve the above problems, the present application provides a method for determining the life of a wheel disc based on the characteristics of a multi-notch fatigue test sample, comprising the following steps: obtaining the stress characteristics of the key positions of the aero-engine wheel disc; the stress characteristics include the maximum stress at the notch, the relative stress gradient, the stress gradient on the notch normal path and the distance away from the notch; based on the stress characteristics, establishing a multi-notch fatigue test sample geometric model, the multi-notch fatigue test sample geometric model is provided with multiple notches, and the design variables of each notch correspond to the key positions of the wheel disc; the design variables of the multi-notch fatigue test sample geometric model include the notch radius R, the notch depth D and the test sample radius W; determining an optimization target and an optimization design variable according to a multi-notch fatigue specimen geometry model; the optimization target is an optimized stress characteristic; constructing an optimal structure model based on the optimization design variable, and calculating a stress characteristic corresponding to the optimal structure model as an actual stress characteristic; performing error verification according to the actual stress characteristic and the optimization target, and if the error is within a standard range, the stress characteristic corresponding to the optimization target is used to confirm the life of a key position of a disk.
[0006] wherein a mathematical relationship between the stress characteristics is represented as: wherein, is a corresponding stress gradient, is a maximum stress at a notch, is a stress gradient at the notch, and x is a distance away from the notch.
[0007] When the multi-notch fatigue specimen geometry model is established, the distance between each notch is greater than 10 mm.
[0008] Determining the optimization target and the optimization design variable includes: importing the multi-notch fatigue specimen geometry model into a finite element software, taking the integral of the maximum stress at the notch and its corresponding stress gradient and the stress difference in the notch influence range as the optimization target, parameterizing the design target in the finite element software according to the design variable, and generating DOE data; According to the DOE data, the optimal solution of the design variable of each notch is obtained by using the optimization algorithm MOGA. The stress distribution at each notch is obtained using the optimal solution of the design variable of each notch.
[0009] Constructing the optimal structure model refers to establishing the geometry model and the finite element model of the multi-notch fatigue specimen according to the optimization design variable.
[0010] When the optimization target is performed, the maximum stress at the notch of the notch fatigue specimen and its corresponding stress gradient correspond to the key position of the disk, the stress curve of the specimen in the notch influence range and the stress curve of the key position of the disk are consistent to the greatest extent, and the integral of the stress difference in the notch influence range is also taken as the optimization target.
[0011] Further, if the error is greater than the standard range, the optimization target and the optimization design variable are determined again.
[0012] According to the application, multiple notch stress distributions of an aero-engine disc can be simulated on a fatigue specimen, the key positions of the disc are corresponded to the notches of the specimen by optimizing the notch radius, the notch depth and the specimen radius, the maximum stress at the notch and the corresponding stress gradient error are minimized, the design requirements of the notch fatigue simulation piece are met, the consistency of the stress distribution of the specimen notch and the key positions of the disc is fully ensured, and the test cost of the disc fatigue life simulation piece is reduced. BRIEF DESCRIPTION OF DRAWINGS
[0013] Figure 1 A method for determining the disc life based on the characteristics of the multi-notch fatigue specimen is provided according to the embodiment of the application; Figure 2 A structural schematic diagram of the multi-notch fatigue specimen is provided according to the embodiment of the application; Figure 3 A flowchart for determining the disc life based on the characteristics of the multi-notch fatigue specimen is provided according to the embodiment of the application; Figure 4 A schematic diagram of the maximum stress and the stress gradient at the notch of a typical fatigue specimen is provided according to the embodiment of the application. DETAILED DESCRIPTION
[0014] The application provides a method for determining the disc life based on the characteristics of the multi-notch fatigue specimen, in which the stress characteristics of multiple notches are integrated into a single fatigue specimen, and the geometric parameters are used for multi-objective optimization to obtain the optimized maximum stress and stress gradient for realizing the determination of the disc life, and meanwhile, the finite element verification is used to verify the consistency of the stress distribution of the specimen and the key positions of the disc.
[0015] The design structure of the multi-notch fatigue specimen provided by the application is to integrate multiple notches into a fatigue specimen, Figure 2 A fatigue specimen schematic diagram including two notches is provided, as shown in the figure, the radius of the left notch is R1, the notch depth is D1, the radius of the right notch is R2, the notch depth is D2, the design variable of each notch is the notch radius R, the notch depth D and the specimen radius W, and the specific implementation mode of the application is described in detail in combination with the description of the drawings.
[0016] Figure 1 A method step for determining the disc life based on the characteristics of the multi-notch fatigue specimen is provided, as shown in the figure, including: Step S100: acquiring the stress characteristics of the key positions of the aero-engine disc; the stress characteristics include the maximum stress at the notch, the relative stress gradient, the stress gradient on the notch normal path and the distance away from the notch; In this step, the stress and the gradient of the key positions of the aero-engine disc are acquired through the finite element analysis, and when the relative stress gradient is calculated, the calculation relationship is represented as: , wherein, is the relative stress gradient, is the maximum stress at the notch, is the stress gradient at the notch, x is the distance away from the notch.
[0017] The maximum stress at the notch and its stress gradient distribution of a typical fatigue specimen are shown in Figure 4 .
[0018] Step S110: Based on the stress characteristics, a multi-notch fatigue specimen geometric model is established in a CAD software, the multi-notch fatigue specimen geometric model is provided with a plurality of notches, and the design variable of each notch corresponds to the key position of the disc; the design variable of the notch fatigue specimen geometric model includes: notch radius R, notch depth D and specimen radius W; When the multi-notch fatigue specimen geometric model is established, the distance between the notches needs to be controlled, and the distance between each notch is greater than 10 mm.
[0019] Step S120: Determine the optimization target and optimization design variable according to the multi-notch fatigue specimen geometric model; the optimization target is the optimized stress characteristics; The process of determining the optimization target and optimization design variable includes: 1) Import the multi-notch fatigue specimen geometric model into the finite element software, and take the integral of the maximum stress at the notch and its corresponding stress gradient, the stress difference in the notch influence range as the optimization target; at the same time, in the finite element software, parameterize the design variable (notch radius R, notch depth D and specimen radius W) to generate DOE data; DOE data (Design of experiments) is a structured data set that can reflect the relationship between design parameters and application characteristics, which can be collected through experimental design method, in this step, CCD (Central Composite Design) method can be used to generate DOE data through finite element software.
[0020] At this time, the maximum stress at the notch of the notch fatigue specimen and its relative stress gradient correspond to the key position of the disc, and the stress curve of the specimen in the notch influence range is consistent with the stress curve of the key position of the disc to the greatest extent, and the integral of the stress difference in the notch influence range is taken as the optimization target.
[0021] 2) According to the DOE data, the optimal solution of the design variable of each notch is obtained by using the optimization algorithm MOGA (Multi-Objective Genetic Algorithm), that is, the optimal radius, depth and sample radius of the key position of the wheel disc corresponding to each notch are obtained, and the optimization design of the multi-notch fatigue sample is realized.
[0022] In this step, the optimal solution of the optimization algorithm interpolation is obtained.
[0023] 3) After obtaining the theoretical value, the stress distribution at each notch is obtained by using the optimized geometric size, that is, the optimal solution of the design variable of each notch, in the subsequent step.
[0024] Step S130: constructing an optimal structure model based on the optimization design variable, and calculating the stress characteristics corresponding to the optimal structure model as actual stress characteristics. In this step, the construction of the optimal structure model means that the geometric model and the finite element model of the multi-notch fatigue sample are established according to the optimization design variable.
[0025] Step S140: error verification according to the actual stress characteristics and the optimization target. In the process of error verification, if the error is within the standard range, the stress characteristics corresponding to the optimization target are used to confirm the life of the key position of the wheel disc; if the error is greater than the standard range, the optimization target and the optimization design variable are re-determined. In the error verification, the maximum stress at the test notch is needed to be guaranteed first The consistency with the key position of the wheel disc, and then the consistency of the corresponding stress gradient.
[0026] Through the error verification, it is determined that the optimization result of the optimization target is consistent with the expected target, and the stress characteristics embodied by the optimization target that passes the error verification can be used to confirm the life of the key position of the wheel disc.
[0027] In the present application, the stress distribution of multiple notches of an aero-engine wheel disc can be simulated on one fatigue sample, the key position of the wheel disc is one-to-one corresponding to the sample notch by optimizing the notch radius, notch depth and sample radius, the maximum stress at the notch and the relative stress gradient error are minimized, the design requirements of the notch fatigue simulation piece are met, the consistency of the stress distribution of the sample notch and the key position of the wheel disc is fully guaranteed, and the test cost of the wheel disc fatigue life simulation piece is reduced.
[0028] In general, the specific steps of the method for determining the life of the wheel disc through the characteristics of the multi-notch fatigue sample provided by the present application are as follows Figure 3The stress characteristics of key positions of the engine disc are obtained according to finite element analysis of the disc, the geometric size of the multi-notch sample is designed, the geometric model of the multi-notch sample is established, the experimental data are generated by combining the parametric finite element analysis design method, the optimization of the notch radius, the depth and the sample radius of the sample is carried out by using the multi-objective optimization design, then the consistency of the stress distribution of the sample and the key positions of the disc is verified by the finite element, and if the sample size corresponding to the stress characteristics meeting the consistency requirement can be used to determine the fatigue life of the disc.
[0029] By the scheme provided by the application, the application fills the blank of the design and application of the multi-notch fatigue sample, enriches the sample type of the notch fatigue test, establishes the foundation for the determination of the fatigue life of the disc at a lower cost, the fatigue life test of the corresponding position of the disc and the life prediction.
[0030] The above disclosed are only several specific embodiments of the application, but the application is not limited to this, and any change conceived by those skilled in the art should fall into the protection scope of the application.
Claims
1. A method of determining the life of a wheel disc based on the characteristics of a multi-notch fatigue specimen, characterized by, The method comprises the following steps: obtaining stress characteristics of a key position of an aero-engine disk; the stress characteristics include maximum stress at a notch, relative stress gradient, stress gradient on a notch normal path, and distance of the stress gradient away from the notch; based on the stress characteristics, establishing a multi-notch fatigue specimen geometric model, the multi-notch fatigue specimen geometric model is provided with multiple notches, and a design variable of each notch corresponds to the key position of the disk; the design variable of the multi-notch fatigue specimen geometric model includes a notch radius R, a notch depth D, and a specimen radius W; determining an optimization target and an optimization design variable according to the multi-notch fatigue specimen geometric model; the optimization target is an optimized stress characteristic; based on the optimization design variable, constructing an optimal structure model, and calculating an actual stress characteristic corresponding to the optimal structure model as the actual stress characteristic; performing error verification according to the actual stress characteristic and the optimization target; if the error is within a standard range, the stress characteristic corresponding to the optimization target is used to confirm a service life of the key position of the disk.
2. The method of determining the life of a wheel disc based on the characteristics of a multi-notch fatigue specimen according to claim 1, characterized in that, a mathematical relationship between the stress characteristics is represented as: wherein, is the relative stress gradient, is the maximum stress at the notch, is the stress gradient at the notch, x is the distance from the notch.
3. The method of determining the life of a wheel disc based on the characteristics of a multi-notch fatigue specimen according to claim 1, characterized in that, when the multi-notch fatigue specimen geometric model is established, a distance between each notch is greater than 10 mm.
4. The method of determining the life of a wheel disc based on the characteristics of a multi-notch fatigue specimen according to claim 1, characterized in that, the determination of the optimization target and the optimization design variable includes: importing the multi-notch fatigue specimen geometric model into finite element software, taking maximum stress at a notch and a corresponding stress gradient and an integral of a stress difference in a notch influence range as an optimization target, parameterizing a design target in the finite element software according to a design variable, and generating DOE data; according to the DOE data, obtaining an optimal solution of the design variable of each notch by using an optimization algorithm MOGA; using the optimal solution of the design variable of each notch to obtain stress distribution at each notch.
5. The method of determining the life of a wheel disc based on the characteristics of a multi-notch fatigue specimen according to claim 4, characterized in that, the construction of the optimal structure model refers to establishing a multi-notch fatigue specimen geometric model and a finite element model according to the optimization design variable.
6. The method of determining the life of a wheel disc based on the characteristics of a multi-notch fatigue specimen according to claim 5, characterized in that, The optimization target is the notch maximum stress of the notch fatigue test sample and its corresponding stress gradient Corresponding to the key position of the wheel disc, the stress curve of the sample in the notch influence range is consistent with the stress curve of the key position of the wheel disc to the greatest extent, and the integral of the stress difference in the notch influence range is simultaneously taken as the optimization target.
7. The method for determining the life of a wheel disc based on the characteristics of a multi-notch fatigue specimen according to claim 1, characterized in that, if the error is greater than the standard range, the optimization target and the optimization design variable are determined again.