Single crystal turbine blade simulation piece test parameter design method and system

Abstract

The invention relates to the technical field of turbine blade life analysis, and discloses a single crystal turbine blade simulation piece test parameter design method and system.The critical distance is adopted to correct the dangerous position of a single crystal turbine blade high-low cycle composite fatigue simulation piece, and then resonance analysis of different orders is carried out to obtain the maximum value of the vibration stress of the dangerous position; and finally, analyzing the static stress value of the dangerous position and the maximum value of the vibration stress to obtain a high-low cycle load ratio of the dangerous film hole so as to carry out high-low cycle composite fatigue test load spectrum design of the dangerous film hole and obtain a composite fatigue test load spectrum for carrying out high-low cycle composite fatigue life test analysis on the single crystal turbine blade simulation part. The influence of the static stress gradient on the high-low cycle composite fatigue life is considered, the sensitivity of the stress gradient to the life is reduced, and the problem that the life evaluation error is large due to the fact that the evaluation is conservative by directly adopting a multi-axis fatigue model based on the stress of the stress concentration position is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of turbine blade life analysis, and discloses a test parameter design method and system for a single crystal turbine blade simulation part. Background Art

[0002] With the demand for increasing efficiency of aircraft engines, increasing the inlet temperature of hot-end turbine blades is an important way. The inlet temperature of the hot-end turbine of the next generation of engines is expected to reach 2300-2400K, which has exceeded the temperature limit that nickel-based single crystal high-temperature alloys can withstand. Therefore, effective cooling protection measures can prevent it from being corroded and damaged by high temperature, of which advanced air film cooling technology accounts for about 60%-70%. However, the air film holes on the air-cooled blades have a certain impact on fatigue strength and service life due to stress concentration.

[0003] The working environment of air-cooled single-crystal turbine blades is extremely harsh and they are threatened by multiple damage mechanisms. Existing failure statistics show that fatigue failures caused by high- and low-cycle composite fatigue account for 38% of the total, posing a serious threat to the structural integrity of the engine. When the turbine blade is in service, its air film holes are simultaneously subjected to low-frequency, high-amplitude centrifugal loads and high-frequency, low-amplitude vibration loads superimposed on them. High-amplitude centrifugal loads lead to low-cycle fatigue failures, and vibration loads lead to high-cycle fatigue failures. A single study of low-cycle fatigue or high-cycle fatigue cannot accurately analyze the fatigue failure problem of the actual structure. Therefore, it is very necessary to study the life design method of single-crystal turbine blade air film holes under high- and low-cycle composite fatigue loads. Summary of the invention

[0004] The purpose of the present invention is to provide a test parameter design method and system for a single crystal turbine blade simulation component, which can reduce the sensitivity of stress gradient to life and avoid the problem of directly using a multi-axis fatigue model to evaluate the stress based on the stress concentration position, which is more conservative and leads to large errors in the estimated life.

[0005] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0006] The test parameter design method of single crystal turbine blade simulation includes:

[0007] Based on the finite element model of the orthotropic single crystal turbine blade with air film holes, the static strength analysis of the single crystal turbine blade with air film holes under the strength life design point is carried out, and the static stress distribution of the single crystal turbine blade with air film holes under the corresponding working condition is obtained;

[0008] According to the static stress distribution of the single crystal turbine blade with air film holes, the position with the maximum static stress is determined as the dangerous position of the single crystal turbine blade;

[0009] According to the dangerous position, the low cycle test stress value of the high and low cycle composite fatigue test is obtained by using the critical distance method;

[0010] Conducting resonance analysis of different orders on the finite element model of the single crystal turbine blade with air film holes to obtain the maximum value of the vibration stress at the dangerous position of the single crystal turbine blade with air film holes;

[0011] According to the low-cycle and high-cycle life design requirements of single-crystal turbine blades, the number of high-cycle cycles under each low-cycle load is calculated, and based on the low-cycle test stress value and the maximum vibration stress value, a high- and low-cycle composite fatigue test load spectrum of a single-crystal turbine blade with air film holes based on a single-crystal turbine blade simulation part is constructed.

[0012] Furthermore, the test temperature of the high- and low-cycle composite fatigue test of a single-crystal turbine blade with air film holes based on a single-crystal turbine blade simulation part is the temperature value of the dangerous position under the working condition corresponding to the maximum static stress.

[0013] Furthermore, the critical distance method is used to determine the static stress value at the location with a distance L along the direction of the maximum stress gradient at the dangerous position as the low-cycle test stress value, where Δσ0 is the fatigue limit of the standard round bar of single crystal turbine blade material, ΔK th is the stress intensity factor threshold, ΔK th According to the fatigue crack growth rate curve model of single crystal turbine blade material The analysis shows that a is the crack length, N is the number of fatigue test cycles of the single crystal turbine blade material under different test stress values, d is the differential sign, and f is related to the lattice orientation of the single crystal turbine blade material. C and m are fitting parameters, which are obtained by fitting the fatigue test data of single crystal turbine blade materials.

[0014] Furthermore, a method for constructing a high- and low-cycle composite fatigue test load spectrum of a single crystal turbine blade with air film holes based on a single crystal turbine blade simulation part includes:

[0015] According to the low-cycle and high-cycle life design requirements of single-crystal turbine blades, the number of high-cycle cycles for each low-cycle load is calculated. Where N L N is the design requirement value for low cycle life. H Design requirement for high cycle life;

[0016] The low cycle test stress value is used as the low cycle load of the high and low cycle composite fatigue test load spectrum;

[0017] σ L -σ H is the minimum value of high cyclic stress and σ L +σ HThe high-cycle stress is the maximum value. The high-cycle load is superimposed on each low-cycle load to obtain the high- and low-cycle composite fatigue test load spectrum of the single crystal turbine blade with air film holes.

[0018] In order to achieve the above technical effects, the present invention also provides a single crystal turbine blade simulation test parameter design system, including:

[0019] Finite element analysis module, which is used to carry out static strength analysis of the working condition to be analyzed under the strength life design point of the single crystal turbine blade with air film hole based on the orthotropic finite element model of the single crystal turbine blade with air film hole, and obtain the static stress distribution of the single crystal turbine blade with air film hole under the corresponding working condition;

[0020] A dangerous position determination module, used to determine the position with maximum static stress as the dangerous position of the single crystal turbine blade according to the static stress distribution of the single crystal turbine blade with air film holes;

[0021] A low-cycle stress analysis module, used to obtain the low-cycle test stress value of the high-low cycle composite fatigue test by using the critical distance method according to the dangerous position;

[0022] A vibration stress analysis module, used to carry out resonance analysis of different orders on the finite element model of the single crystal turbine blade with air film holes, and obtain the maximum value of the vibration stress at the dangerous position of the single crystal turbine blade with air film holes;

[0023] The load spectrum generation module is used to calculate the number of high-cycle cycles under each low-cycle load according to the low-cycle and high-cycle life design requirements of the single-crystal turbine blades, and based on the low-cycle test stress value and the maximum vibration stress value, construct a high- and low-cycle composite fatigue test load spectrum of a single-crystal turbine blade with air film holes based on a single-crystal turbine blade simulation part.

[0024] Furthermore, it also includes a test temperature determination module for determining the temperature value of the dangerous position under the working condition corresponding to the maximum static stress as the test temperature for the high and low cycle composite fatigue test of the single crystal turbine blade with air film holes.

[0025] Furthermore, in the low-cycle stress analysis module, the critical distance method is used to determine the static stress value at the position with a distance L along the maximum stress gradient direction at the dangerous position as the low-cycle test stress value, where Δσ0 is the fatigue limit of the standard round bar of single crystal turbine blade material, ΔK th is the stress intensity factor threshold, ΔK th According to the fatigue crack growth rate curve model of single crystal turbine blade material The analysis shows that a is the crack length, N is the number of fatigue test cycles of the single crystal turbine blade material under different test stress values, d is the differential sign, and f is related to the lattice orientation of the single crystal turbine blade material. C and m are fitting parameters, which are obtained by fitting the fatigue test data of single crystal turbine blade materials.

[0026] Furthermore, in the load spectrum generation module, the high-cycle cycle number of each low-cycle load is calculated according to the low-cycle and high-cycle life design requirements of the single-crystal turbine blade. Where N L N is the design requirement value for low cycle life. H is the high cycle life design requirement value; the low cycle test stress value is used as the low cycle load of the high and low cycle composite fatigue test load spectrum; σ L -σ H is the minimum value of high cyclic stress and σ L +σ H The high-cycle stress is the maximum value. The high-cycle load is superimposed on each low-cycle load to obtain the high- and low-cycle composite fatigue test load spectrum of the single crystal turbine blade with air film holes.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] In the load spectrum design process of the high and low cycle composite fatigue simulation parts of the single crystal turbine blades, the present invention adopts the critical distance method to determine the dangerous position, takes into account the influence of static stress gradient on the high and low cycle composite fatigue life, reduces the sensitivity of stress gradient to life, and avoids the problem of directly using a multi-axis fatigue model to evaluate the stress based on the stress concentration position, which is more conservative and leads to large errors in the estimated life. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of the test parameter design method of the single crystal turbine blade simulation part in the embodiment;

[0030] Figure 2 It is a structural block diagram of the test parameter design system of the single crystal turbine blade simulation part in the embodiment;

[0031] Figure 3 It is a schematic diagram of the load spectrum of the composite fatigue test in the embodiment;

[0032] Among them, 1. Finite element analysis module; 2. Dangerous position determination module; 3. Low-cycle stress analysis module; 4. Vibration stress analysis module; 5. Load spectrum generation module; 6. Test temperature determination module. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the embodiments and drawings. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0034] Example

[0035] See also Figure 1 , the test parameter design method of single crystal turbine blade simulation includes:

[0036] Based on the finite element model of the orthotropic single crystal turbine blade with air film holes, the static strength analysis of the single crystal turbine blade with air film holes under the strength life design point is carried out, and the static stress distribution of the single crystal turbine blade with air film holes under the corresponding working condition is obtained;

[0037] According to the static stress distribution of the single crystal turbine blade with air film holes, the position with the maximum static stress is determined as the dangerous position of the single crystal turbine blade;

[0038] According to the dangerous position, the low cycle test stress value of the high and low cycle composite fatigue test is obtained by using the critical distance method;

[0039] Conducting resonance analysis of different orders on the finite element model of the single crystal turbine blade with air film holes to obtain the maximum value of the vibration stress at the dangerous position of the single crystal turbine blade with air film holes;

[0040] According to the low-cycle and high-cycle life design requirements of single-crystal turbine blades, the number of high-cycle cycles under each low-cycle load is calculated, and based on the low-cycle test stress value and the maximum vibration stress value, a high- and low-cycle composite fatigue test load spectrum of a single-crystal turbine blade with air film holes based on a single-crystal turbine blade simulation part is constructed.

[0041] In this embodiment, the static stress distribution of the single crystal turbine blade with air film holes is obtained by carrying out finite element analysis, and the position of the maximum static stress is determined to be the dangerous position of the single crystal turbine blade. Then, the low-cycle stress test value of the high-low cycle composite fatigue simulation of the single crystal turbine blade is corrected by using the critical distance; then, resonance analysis of different orders is carried out on the single crystal turbine blade with air film holes to obtain the maximum value of the vibration stress at the dangerous position; finally, the corrected low-cycle stress test value and the maximum value of the vibration stress are used to construct the high-low cycle composite fatigue test load spectrum of the single crystal turbine blade with air film holes based on the single crystal turbine blade simulation. In the load spectrum design process for the high-low cycle composite fatigue simulation of the single crystal turbine blade in this embodiment, the critical distance method is used to determine the low-cycle stress test value, and the influence of the static stress gradient on the high-low cycle composite fatigue life is considered, the sensitivity of the stress gradient to the life is reduced, and the problem of large error in the life evaluation caused by directly using the multi-axis fatigue model to evaluate the stress based on the stress concentration position is more conservative.

[0042] In this embodiment, the temperature value of the dangerous position under the working condition corresponding to the maximum static stress is used as the test temperature of the high-low cycle composite fatigue test of the single crystal turbine blade with air film hole. This temperature is the lowest temperature of the composite fatigue life of the dangerous air film hole, and the high-low cycle composite fatigue life of the single crystal turbine blade under extreme conditions can be obtained, thereby improving the service reliability of the engine.

[0043] In this embodiment, the critical distance method is used to determine the static stress value at the location where the distance L along the maximum stress gradient direction at the dangerous position is the low-cycle test stress value, where Δσ0 is the fatigue limit of the standard round bar of single crystal turbine blade material, ΔK th is the stress intensity factor threshold, ΔK th According to the fatigue crack growth rate curve model of single crystal turbine blade material The analysis shows that a is the crack length, N is the number of fatigue test cycles of the single crystal turbine blade material under different test stress values, d is the differential sign, and f is related to the lattice orientation of the single crystal turbine blade material. C and m are fitting parameters, which are obtained by fitting the fatigue test data of single crystal turbine blade materials.

[0044] In this embodiment, a method for constructing a high- and low-cycle composite fatigue test load spectrum of a single-crystal turbine blade with air film holes based on a single-crystal turbine blade simulator includes:

[0045] According to the low-cycle and high-cycle life design requirements of single-crystal turbine blades, the number of high-cycle cycles for each low-cycle load is calculated. Where N L N is the design requirement value for low cycle life. H It is the design requirement value of high cycle life, generally 1×10 7 ~3×10 7 ;

[0046] The low cycle test stress value is used as the low cycle load of the high and low cycle composite fatigue test load spectrum;

[0047] σ L -σ H is the minimum value of high cyclic stress and σ L +σ H is the maximum value of high-cycle stress. The high-cycle load is superimposed on each low-cycle load to obtain the high- and low-cycle composite fatigue test load spectrum of the single crystal turbine blade with air film holes, as shown in Figure 3 shown.

[0048] Based on the same inventive concept, this embodiment also provides a single crystal turbine blade simulation test parameter design system, such as Figure 2 As shown, including:

[0049] Finite element analysis module 1 is used to carry out static strength analysis of the working condition to be analyzed under the strength life design point of the single crystal turbine blade with air film holes based on the orthotropic finite element model of the single crystal turbine blade with air film holes, and obtain the static stress distribution of the single crystal turbine blade with air film holes under the corresponding working condition;

[0050] Dangerous position determination module 2, used to determine the position with maximum static stress as the dangerous position of the single crystal turbine blade according to the static stress distribution of the single crystal turbine blade with air film holes;

[0051] A low-cycle stress analysis module 3 is used to analyze and obtain the low-cycle test stress value of the high-low cycle composite fatigue test by using a critical distance method according to the dangerous position;

[0052] A vibration stress analysis module 4 is used to perform resonance analysis of different orders on the finite element model of the single crystal turbine blade with air film holes to obtain the maximum value of the vibration stress at the dangerous position of the single crystal turbine blade with air film holes;

[0053] The load spectrum generation module 5 is used to calculate the number of high-cycle cycles under each low-cycle load according to the low-cycle and high-cycle life design requirements of the single-crystal turbine blades, and to construct a high- and low-cycle composite fatigue test load spectrum of a single-crystal turbine blade with air film holes based on a single-crystal turbine blade simulation part based on the low-cycle test stress value and the maximum value of the vibration stress.

[0054] In addition, the single crystal turbine blade simulation test parameter design system in this embodiment also includes a test temperature determination module 6, which is used to determine the temperature value of the dangerous position under the working condition corresponding to the maximum static stress as the test temperature for the high and low cycle composite fatigue test of the single crystal turbine blade with air film holes.

[0055] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for designing test parameters of a single crystal turbine blade simulation component, characterized in that: include: Based on the finite element model of the orthotropic single crystal turbine blade with air film holes, the static strength analysis of the single crystal turbine blade with air film holes under the strength life design point is carried out, and the static stress distribution of the single crystal turbine blade with air film holes under the corresponding working condition is obtained; According to the static stress distribution of the single crystal turbine blade with air film holes, the position with the maximum static stress is determined as the dangerous position of the single crystal turbine blade; According to the dangerous position, the low cycle test stress value of the high and low cycle composite fatigue test is obtained by using the critical distance method; Conducting resonance analysis of different orders on the finite element model of the single crystal turbine blade with air film holes to obtain the maximum value of the vibration stress at the dangerous position of the single crystal turbine blade with air film holes; According to the low-cycle and high-cycle life design requirements of single-crystal turbine blades, the number of high-cycle cycles under each low-cycle load is calculated, and based on the low-cycle test stress value and the maximum vibration stress value, a high- and low-cycle composite fatigue test load spectrum of a single-crystal turbine blade with air film holes based on a single-crystal turbine blade simulation part is constructed.

2. The single crystal turbine blade simulation test parameter design method according to claim 1, characterized in that: The test temperature of the high- and low-cycle combined fatigue test of a single-crystal turbine blade with air film holes based on a single-crystal turbine blade simulation is the temperature value of the dangerous position under the working condition corresponding to the maximum static stress.

3. The single crystal turbine blade simulation test parameter design method according to claim 1, characterized in that: The critical distance method is used to determine the static stress value at the location with a distance L along the direction of the maximum stress gradient at the dangerous position as the low-cycle test stress value, where Δσ0 is the fatigue limit of the standard round bar of single crystal turbine blade material, ΔK th is the stress intensity factor threshold, ΔK th According to the fatigue crack growth rate curve model of single crystal turbine blade material The analysis shows that a is the crack length, N is the number of fatigue test cycles of the single crystal turbine blade material under different test stress values, d is the differential sign, and f is related to the lattice orientation of the single crystal turbine blade material. C and m are fitting parameters, which are obtained by fitting the fatigue test data of single crystal turbine blade materials.

4. The single crystal turbine blade simulation test parameter design method according to claim 3, characterized in that: The method for constructing a high- and low-cycle composite fatigue test load spectrum of a single-crystal turbine blade with air film holes based on a single-crystal turbine blade simulator includes: According to the low-cycle and high-cycle life design requirements of single-crystal turbine blades, the number of high-cycle cycles for each low-cycle load is calculated. Where N L N is the design requirement value for low cycle life. H Design requirement for high cycle life; The low cycle test stress value is used as the low cycle load of the high and low cycle composite fatigue test load spectrum; σ L -σ H is the minimum value of high cyclic stress and σ L +σ H The high-cycle stress is the maximum value. The high-cycle load is superimposed on each low-cycle load to obtain the high- and low-cycle composite fatigue test load spectrum of the single crystal turbine blade with air film holes.

5. Single crystal turbine blade simulation test parameter design system, characterized in that: include: Finite element analysis module, which is used to carry out static strength analysis of the working condition to be analyzed under the strength life design point of the single crystal turbine blade with air film hole based on the orthotropic finite element model of the single crystal turbine blade with air film hole, and obtain the static stress distribution of the single crystal turbine blade with air film hole under the corresponding working condition; A dangerous position determination module, used to determine the position with maximum static stress as the dangerous position of the single crystal turbine blade according to the static stress distribution of the single crystal turbine blade with air film holes; A low-cycle stress analysis module, used to obtain the low-cycle test stress value of the high-low cycle composite fatigue test by using the critical distance method according to the dangerous position; A vibration stress analysis module, used to carry out resonance analysis of different orders on the finite element model of the single crystal turbine blade with air film holes, and obtain the maximum value of the vibration stress at the dangerous position of the single crystal turbine blade with air film holes; The load spectrum generation module is used to calculate the number of high-cycle cycles under each low-cycle load according to the low-cycle and high-cycle life design requirements of the single-crystal turbine blades, and based on the low-cycle test stress value and the maximum vibration stress value, construct a high- and low-cycle composite fatigue test load spectrum of a single-crystal turbine blade with air film holes based on a single-crystal turbine blade simulation part.

6. The single crystal turbine blade simulation test parameter design system according to claim 5, characterized in that: It also includes a test temperature determination module for determining the temperature value of the dangerous position under the working condition corresponding to the maximum static stress as the test temperature for the high and low cycle composite fatigue test of the single crystal turbine blade with air film holes.

7. The single crystal turbine blade simulation test parameter design system according to claim 5, characterized in that: In the low-cycle stress analysis module, the critical distance method is used to determine the static stress value at the dangerous position at a distance L along the maximum stress gradient direction as the low-cycle test stress value, where Δσ0 is the fatigue limit of the standard round bar of single crystal turbine blade material, ΔK th is the stress intensity factor threshold, ΔK th According to the fatigue crack growth rate curve model of single crystal turbine blade material The analysis shows that a is the crack length, N is the number of fatigue test cycles of the single crystal turbine blade material under different test stress values, d is the differential sign, and f is related to the lattice orientation of the single crystal turbine blade material. C and m are fitting parameters, which are obtained by fitting the fatigue test data of single crystal turbine blade materials.

8. The single crystal turbine blade simulation test parameter design system according to claim 7, characterized in that: In the load spectrum generation module, the high-cycle number of cycles of each low-cycle load is calculated according to the low-cycle and high-cycle life design requirements of the single-crystal turbine blade. Where N L N is the design requirement value for low cycle life. H is the high cycle life design requirement value; the low cycle test stress value is used as the low cycle load of the high and low cycle composite fatigue test load spectrum; σ L -σ H is the minimum value of high cyclic stress and σ L +σ H The high-cycle stress is the maximum value. The high-cycle load is superimposed on each low-cycle load to obtain the high- and low-cycle composite fatigue test load spectrum of the single crystal turbine blade with air film holes.

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