Method and system for calculating fatigue creep interaction coupling damage factor of material
By calculating the damage factor coupled with the fatigue-creep interaction of materials, the problem of the failure to quantify the nonlinear coupling between fatigue and creep in the existing technology has been solved, thereby improving the accuracy and reliability of life prediction for high-temperature components.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- AECC HUNAN AVIATION POWERPLANT RES INST
- Filing Date
- 2026-01-13
- Publication Date
- 2026-05-12
AI Technical Summary
Existing life prediction methods under fatigue and creep interaction have failed to fully consider nonlinear coupling effects, resulting in conservative or unsafe prediction results, especially in high-temperature structural components such as aero engines.
A method for calculating the coupled damage factor of material fatigue-creep interaction is provided. By obtaining the alternating fatigue damage factor per unit time, the creep damage factor per unit time, and the fracture life of fatigue-creep interaction, the coupled damage factor is calculated, and the nonlinear mutual promotion effect between fatigue and creep is quantified.
It significantly improves the accuracy and reliability of life prediction for high-temperature components under complex loads, providing a scientific basis for the safety design and life assessment of key equipment such as aero engines.
Smart Images
Figure CN122024950A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of material mechanical property testing and life prediction technology, and specifically relates to a method and system for calculating the damage factor coupled by material fatigue creep interaction. Background Technology
[0002] In high-temperature structural components such as aero-engines and gas turbines, metallic materials often simultaneously endure cyclic loading (fatigue) and sustained static loading (creep). A strong interaction exists between fatigue and creep, significantly impacting the service life of the material. Currently, commonly used life prediction methods are mostly based on linear cumulative damage criteria, such as Miner's rule and Robinson's rule. Under fatigue-creep interactive conditions, the two are typically simply added together (D... fatigue + D creep = 1) As a failure criterion, the nonlinear coupling effect between fatigue and creep is not fully considered, resulting in prediction results that are too conservative or unsafe. For example, in a creep fatigue damage calculation method under a variable load history disclosed in CN115691720A, a load interaction factor θ is introduced to consider the influence of multi-level load sequence, but its damage accumulation model is still essentially linear, and its prediction results are too conservative or unsafe. Summary of the Invention
[0003] To address the aforementioned issues, this application provides a method and system for calculating the damage factor coupled by the interaction of material fatigue and creep.
[0004] The first objective of this application is to provide a method for calculating the damage factor coupled with the fatigue-creep interaction of materials, including: Obtain the alternating fatigue damage factor per unit time of the material under stress amplitudes with fixed maximum and minimum stresses; Obtain the creep damage factor per unit time of the material under different constant load stresses within a preset stress range; Obtain the fatigue creep interaction fracture life of the material under the holding time; The fatigue-creep interaction coupled damage factor of the material is calculated based on the fracture life, alternating fatigue damage factor per unit time, and creep damage factor per unit time.
[0005] In a specific embodiment of this application, the calculation formula for the damage factor coupled by the material fatigue-creep interaction is as follows:
[0006] Where, N fc For fatigue-creep interaction fracture life, D f The fatigue damage factor is the alternating fatigue factor per unit time, t hFor a fixed holding time, σ is the holding stress, t represents the holding time variable, and Dcoupling is the coupling damage factor; This represents the functional relationship between the creep damage factor and the stress-time function σ(t) for each cycle of load holding. It represents the total creep damage integral over the entire fatigue creep interaction life of the material.
[0007] In a specific embodiment of this application, the preset stress range is bounded by the fixed maximum stress and the fixed minimum stress.
[0008] In a specific embodiment of this application, the alternating fatigue damage factor per unit time is calculated based on the alternating fatigue fracture life under stress amplitudes of fixed maximum stress and fixed minimum stress. The calculation expression for the alternating fatigue damage factor per unit time is as follows: D f =1 / N f Where, N f To determine the alternating fatigue fracture life under stress amplitudes with fixed maximum and minimum stresses, D f It is the fatigue damage factor that varies per unit time.
[0009] In a specific embodiment of this application, the creep damage factor per unit time is calculated based on the creep fracture stress-life curve under different constant holding stresses within a preset stress range.
[0010] In a specific embodiment of this application, the calculation expression for the creep damage factor per unit time is as follows: D C(σ) =1 / tr(σ) Where tr(σ) is the creep fracture stress-life curve under different constant load stresses within the preset stress range. This represents the creep damage factor per unit time.
[0011] In a specific embodiment of this application, the fatigue creep interaction fracture life is obtained by a material fatigue creep interaction test with a fixed maximum stress, a fixed minimum stress, and a fixed holding time, wherein the fatigue creep interaction is a fatigue creep interaction under an upper holding condition or a lower holding condition.
[0012] In a specific embodiment of this application, the material is a metallic material; The metallic material is a nickel-based high-temperature alloy.
[0013] In a specific embodiment of this application, the coupling damage factor is used to quantify the nonlinear mutual promotion effect between fatigue load and creep load.
[0014] The second objective of this application is to provide a calculation system for the damage factor coupled with the fatigue-creep interaction of materials, including: Database module: used to obtain the alternating fatigue damage factor of the material per unit time under stress amplitudes with fixed maximum and minimum stresses; also used to obtain the creep damage factor of the material per unit time under different constant holding stresses within a preset stress range; also used to obtain the fatigue creep interaction fracture life of the material under holding time. Calculation module: Used to calculate the fatigue-creep interaction coupled damage factor of materials based on the fracture life, alternating fatigue damage factor per unit time, and creep damage factor per unit time.
[0015] Compared with the prior art, this application has the following advantages: This application presents a method and system for calculating the coupled damage factor of material fatigue-creep interaction. It obtains the coupled damage factor and uses it to quantify the nonlinear mutual promotion effect between fatigue load and creep load. This breaks through the limitations of traditional linear cumulative damage theory. For the first time, it accurately reveals the nonlinear damage mechanism of fatigue-creep interaction through the quantitative method of coupled damage factor, and solves the problem of difficulty in quantifying coupled damage in the prior art.
[0016] The method described in this application can significantly improve the accuracy and reliability of life prediction for high-temperature components (such as nickel-based superalloy components) under complex loads, providing a more scientific theoretical basis and practical engineering tool for the safety design and life assessment of key equipment such as aero engines.
[0017] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 A flowchart is shown showing a method for calculating the material fatigue creep interaction coupled damage factor according to an embodiment of this application; Figure 2 A schematic diagram of the load spectrum in a fatigue creep interaction test according to Embodiment 1 of this application is shown. Figure 3 A framework diagram of a calculation system for material fatigue creep interaction coupled with damage factor according to an embodiment of this application is shown. In the diagram: 10, Database module; 20, Calculation module. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, 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, 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.
[0021] The terms used in this application are explained as follows: Fatigue: refers to the damage and failure of materials under cyclic loading.
[0022] Creep: refers to the continuous deformation and failure of a material over time under constant static load (especially at high temperatures).
[0023] Interaction: refers to the mutual influence between the two damage mechanisms of fatigue and creep, which is not a simple additive effect.
[0024] Coupling damage factor: The core concept of this invention, referring to an additional damage factor generated by the interaction between fatigue and creep, independent of pure fatigue and pure creep damage.
[0025] like Figure 1 As shown, a method for calculating the damage factor coupled by material fatigue creep interaction according to certain embodiments of the present invention includes: S1. Obtain the alternating fatigue damage factor of the material per unit time under stress amplitudes with fixed maximum and minimum stresses; Obtain the creep damage factor per unit time of the material under different constant load stresses within a preset stress range; Obtain the fatigue creep interaction fracture life of the material under the holding time; The fatigue-creep interaction coupled damage factor of the material is calculated based on the fracture life, alternating fatigue damage factor per unit time, and creep damage factor per unit time.
[0026] In a specific embodiment of this application, the calculation formula for the material fatigue creep interaction coupled damage factor is shown in equation (1): (1) In equation (1), N fc For fatigue-creep interaction fracture life, D f The fatigue damage factor is the alternating fatigue factor per unit time, t h To maintain a fixed load duration, σ represents the load stress, t represents the variable load duration, and D... coupling For coupling damage factors; It represents the total creep damage integral over the entire fatigue creep interaction life of the material; This represents the functional relationship between the creep damage factor and the stress-time function σ(t) at each cycle of the fatigue creep test. The integral of this term represents the real-time integral of the stress-time function σ(t) at each cycle of the fatigue creep test. The coupling damage factor is a measure of the degree of nonlinear coupling between fatigue load and creep load. In the calculation process of equation (1), the units of stress and time should be consistent, such as N. fc t h If t is uniformly represented as hours, then D f The unit time involved is hours, and the load stress is MPa; It can also be N fc t h If t is uniformly represented as hours, then D f The unit time involved is hours, and the holding stress is Pa. Although this will affect the final size of the coupled damage factor, it does not affect the comparison of different coupled damage factors (the premise for the comparison of different coupled damage factors is that the units in the calculation process are consistent), that is, it does not affect its characterization of the nonlinear coupling effect between fatigue load and creep holding load.
[0027] In some embodiments of this application, the preset stress range is bounded by the fixed maximum stress and the fixed minimum stress.
[0028] In some instances of this application, the alternating fatigue damage factor per unit time is calculated based on the alternating fatigue fracture life under stress amplitudes of fixed maximum and fixed minimum stresses. The calculation expression for the alternating fatigue damage factor per unit time is shown in equation (2): D f =1 / N f (2) In equation (2), N f To determine the alternating fatigue fracture life under stress amplitudes with fixed maximum and minimum stresses, D f It is the fatigue damage factor that varies per unit time.
[0029] In some instances of this application, the creep damage factor per unit time is calculated based on the creep fracture stress-life curves under different constant holding stresses within a preset stress range; The calculation expression for the creep damage factor per unit time is shown in (3): D C(σ) =1 / tr(σ)(3) Where tr(σ) is the creep fracture stress-life curve under different constant holding stresses within the preset stress range (that is, the stress-time function under different constant holding stresses within the preset stress range). This represents the creep damage factor per unit time.
[0030] In some instances of this application, the fatigue creep interaction fracture life is obtained by material fatigue creep interaction tests with fixed maximum stress, fixed minimum stress and fixed holding time, wherein the fatigue creep interaction is fatigue creep interaction under upper holding condition or lower holding condition.
[0031] In some instances of this application, the material is a metallic material, which is a nickel-based high-temperature alloy or a wrought high-temperature alloy.
[0032] In some instances of this application, the coupling damage factor is used to quantify the nonlinear mutual promotion between fatigue load and creep load. The larger the value of the coupling damage factor, the greater the nonlinear coupling between fatigue load and creep load (that is, the greater the nonlinear mutual promotion between fatigue load and creep load).
[0033] The above method for calculating the coupling damage factor is applied to a specific example, as follows: Example 1 This embodiment uses high-quality GH4169 integral bladed disk for high-pressure compressors of aero-engines as the research object, and measures its load-bearing fatigue creep coupling damage factor at 650℃. The test equipment selected is an electro-hydraulic servo fatigue testing machine with a high-temperature environmental chamber and load-bearing function.
[0034] Experimental parameters: (1) Alternating fatigue stress: maximum stress σ max = 800 MPa, minimum stress σ min = 100 MPa.
[0035] (2) Creep holding stress: Within the range of 800 MPa to 100 MPa, three stress levels of 650 MPa, 700 MPa and 750 MPa were selected for creep test.
[0036] (3) Interactive test load holding: The upper load stress is 750 MPa, and the fixed load holding time is t.h = 1min.
[0037] Experimental process and results: (1) Pure fatigue test: The mean fatigue life N was measured. f =15000 cycles.
[0038] (2) Creep test: The creep fracture life tr(750MPa) under stress of 650℃ and 750 MPa was measured to be 300 hours. The creep life curve was obtained by fitting multiple stress points.
[0039] (3) Fatigue creep interaction test: at σ max =800 MPa, σ min The fracture life N was measured under a load spectrum of 100 MPa, with an upper load of 750 MPa maintained for 60 seconds. fc =5000 cycles. The fatigue load spectrum diagram is shown below. Figure 2 As shown.
[0040] Damage factor calculation: (1) Fatigue damage factor: D f =1 / N f =1 / 15000≈6.67e -5 (Each loop) (2) Creep damage factor at 750 MPa: Dc(750MPa)=1 / tr(750MPa)=1 / 300h≈3.33e -3 (per hour) (3) In the interactive test, the holding time for each cycle was 60 seconds (i.e., 1 / 60 hour). Therefore, the creep damage generated in each cycle was Dc(750MPa)*(1 / 60)h≈5.56e -5 (Each loop).
[0041] Calculation of coupling damage factor: According to the overall damage equation: N fc ×D f +N fc ×[creep damage per cycle] + N fc ×D coupling =1 Substitute the data: 5000 × 6.67e -5 +5000×5.56e -5 +5000×D coupling =1 0.3335 + 0.278 + 5000 * D coupling =1 5000×D coupling =1-0.6115=0.3885 D coupling =0.3885 / 5000=7.77e -5 (Each loop) Conclusion: Under the conditions of this embodiment, the coupled damage factor of GH4169 alloy in fatigue creep interaction under load at 650℃ is 7.77e. -5 / cycle. This positive value indicates a significant mutually reinforcing effect between fatigue and creep.
[0042] like Figure 3 As shown, a system for calculating the material fatigue creep interaction coupled with damage factor according to certain embodiments of this application includes: Database module 10: used to obtain the alternating fatigue damage factor of the material per unit time under stress amplitudes with fixed maximum and minimum stresses; also used to obtain the creep damage factor of the material per unit time under different constant holding stresses within a preset stress range; also used to obtain the fatigue creep interaction fracture life of the material under holding time. Calculation module 20: Used to calculate the fatigue-creep interaction coupled damage factor of materials based on the fracture life of fatigue creep interaction, the alternating fatigue damage factor per unit time, and the creep damage factor per unit time.
[0043] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. A method for calculating the damage factor coupled with the fatigue-creep interaction of materials, characterized in that, include: Obtain the alternating fatigue damage factor per unit time of the material under stress amplitudes with fixed maximum and minimum stresses; Obtain the creep damage factor per unit time of the material under different constant load stresses within a preset stress range; Obtain the fatigue creep interaction fracture life of the material under the holding time; The fatigue-creep interaction coupled damage factor of the material is calculated based on the fracture life, alternating fatigue damage factor per unit time, and creep damage factor per unit time.
2. The method for calculating the damage factor coupled by the material fatigue-creep interaction according to claim 1, characterized in that, The formula for calculating the damage factor coupled with the fatigue-creep interaction of the material is as follows: Where, N fc For fatigue-creep interaction fracture life, D f The fatigue damage factor is the alternating fatigue factor per unit time, t h To maintain a fixed load duration, σ represents the load stress, t represents the variable load duration, and D... coupling For coupling damage factors; This represents the functional relationship between the creep damage factor and the stress-time function σ(t) for each cycle of load holding. It represents the total creep damage integral over the entire fatigue creep interaction life of the material.
3. The method for calculating the damage factor coupled by the material fatigue-creep interaction according to claim 1, characterized in that, The preset stress range is bounded by the fixed maximum stress and the fixed minimum stress.
4. The method for calculating the damage factor coupled by the material fatigue creep interaction according to claim 1, characterized in that, The alternating fatigue damage factor per unit time is calculated based on the alternating fatigue fracture life under stress amplitudes of fixed maximum and fixed minimum stresses. The calculation expression for the alternating fatigue damage factor per unit time is as follows: D f =1 / N f Where, N f To determine the alternating fatigue fracture life under stress amplitudes with fixed maximum and minimum stresses, D f It is the fatigue damage factor that varies per unit time.
5. The method for calculating the damage factor coupled by the material fatigue-creep interaction according to claim 1, characterized in that, The creep damage factor per unit time is calculated based on the creep fracture stress-life curves under different constant holding stresses within a preset stress range.
6. The method for calculating the damage factor coupled by the material fatigue creep interaction according to claim 5, characterized in that, The calculation expression for the creep damage factor per unit time is as follows: D C(σ) =1 / tr(σ) Where tr(σ) is the creep fracture stress-life curve under different constant load stresses within the preset stress range. It represents the creep damage factor per unit time.
7. The method for calculating the damage factor coupled by the material fatigue creep interaction according to claim 1, characterized in that, The fatigue creep interaction fracture life is obtained by material fatigue creep interaction test with fixed maximum stress, fixed minimum stress and fixed holding time, wherein the fatigue creep interaction is fatigue creep interaction under upper holding condition or lower holding condition.
8. The method for calculating the damage factor coupled by the material fatigue-creep interaction according to claim 1, characterized in that, The material is a metallic material.
9. The method for calculating the damage factor coupled by the material fatigue creep interaction according to claim 1, characterized in that, The coupling damage factor is used to quantify the nonlinear mutual promotion between fatigue load and creep load.
10. A calculation system for damage factors coupled with fatigue-creep interaction in materials, characterized in that, include: Database module: used to obtain the alternating fatigue damage factor of the material per unit time under stress amplitudes with fixed maximum and minimum stresses; It is also used to obtain the creep damage factor of the material per unit time under different constant holding stresses within a preset stress range; it is also used to obtain the fatigue creep interaction fracture life of the material under holding time. Calculation module: Used to calculate the fatigue-creep interaction coupled damage factor of materials based on the fracture life, alternating fatigue damage factor per unit time, and creep damage factor per unit time.