Aero-engine foreign object damaged blade fatigue strength prediction method based on macro-micro damage three-dimensional feature analysis

Abstract

The invention belongs to the technical field of aero-engine blades, particularly discloses an aero-engine foreign object damaged blade fatigue strength prediction method based on macro and micro damage three-dimensional feature analysis, and aims to carry out notch local high-precision scanning and reconstruction for the high-cycle fatigue strength evaluation problem of the aero-engine blade with foreign object damage. The method comprises the following steps: disclosing macroscopic and microcosmic damage characteristics of a notch, establishing an accurate foreign object damage notch blade high-cycle fatigue strength evaluation model, performing first-order modal simulation by using the model, and performing analysis and calculation on the foreign object damage blade high-cycle fatigue strength by using related parameters obtained by simulation. And an effective fatigue strength prediction result of the blade damaged by the foreign object is obtained. According to the method, the fatigue strength of the aero-engine blade with the foreign object damage notch can be accurately evaluated, theoretical guidance is provided for repair-free or waste judgment of the blade, and the method has important scientific significance and engineering application value.

Description

Technical Field

[0001] The invention belongs to the technical field of aero-engine blades, and in particular relates to a fatigue strength prediction method for aero-engine blades damaged by foreign objects based on three-dimensional feature analysis of macro and micro damage. Background Art

[0002] Fan and compressor blades are the core components of aircraft engines. They are mostly made of surface-strengthened titanium alloy. When the blades rotate at high speed, they are subjected to huge centrifugal force and aerodynamic force, and are very prone to fatigue fracture. When the aircraft is used in harsh natural environments (Gobi, desert, etc.), the engine will inevitably inhale hard objects such as sand, gravel, and screws. These inhaled objects are likely to cause foreign object damage to the fan and compressor blades. Foreign object damage will seriously weaken the fatigue performance of the blades, causing blade fracture, which in turn affects the safe operation of the engine.

[0003] The damage morphology of blades with foreign object damage is very complex. Taking the notch, the main type of damage caused by foreign object damage, as an example, the macro damage notch usually has an irregular geometric shape, and there will be micro damage such as micro cracks around the macro damage notch. In addition to the stress concentration caused by the macro damage notch, the influence of local micro damage (such as cracks) on the fatigue performance of blades due to foreign object damage is more significant. The current way to study the fatigue performance of blades with foreign object damage is to simplify the foreign object damage notch into a macro notch, and does not consider the influence of micro damage around the notch. Therefore, it is necessary to adopt more refined measurement and analysis methods, consider the influence of micro damage around the notch, and achieve more accurate fatigue strength assessment of blades with foreign object damage. Summary of the invention

[0004] The purpose of the present invention is to provide a method for predicting fatigue strength of aircraft engine blades damaged by foreign objects based on three-dimensional feature analysis of macro and micro damage, so as to solve the above problems existing in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, a fatigue strength prediction method for aero-engine blades damaged by foreign objects based on three-dimensional feature analysis of macro and micro damage is provided, comprising:

[0007] Perform optical microscopic measurement on the macroscopic notch of the target foreign object damaged blade to obtain its macroscopic damage geometric characteristic data, and perform CT scanning on the local micro-damage part of the macroscopic notch of the target foreign object damaged blade to obtain its microscopic damage geometric characteristic data;

[0008] A damage data model is constructed based on the macroscopic damage geometric feature data and the microscopic damage geometric feature data of the target foreign object damaged blade, and a complete blade data model corresponding to the target foreign object damaged blade is constructed, and the complete blade data model is superimposed on the damage data model to obtain a damaged blade data model;

[0009] The first-order modal simulation of the damaged blade data model is performed to determine its far-field point and the dangerous point at the root of the notch. The modal stress σ at the far-field point along the length direction of the blade is A'_仿真 , the Mises stress σ at the far-field point A'_Mises_仿真 , and the Mises stress σ at the critical point at the root of the notch B'_Mises_仿真 , perform first-order modal simulation on the complete blade data model to determine the Mises stress σ at the corresponding far-field point A_Mises_仿真 And the Mises stress σ at the critical point at the root of the gap B_Mises_仿真 ;

[0010] Using σ A'_Mises_仿真 , σ B'_Mises_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Calculate the stress concentration factor corresponding to the target foreign object damaged blade, and determine the notch depth and notch width corresponding to the target foreign object damaged blade based on the damage data model;

[0011] The fitting critical distance of the dangerous point at the root of the notch is calculated using the notch depth, notch width and stress concentration factor corresponding to the blade damaged by the target foreign object;

[0012] Based on the first-order modal simulation results of the damaged blade data model, the average stress σ in the hemispherical area along the notch depth direction with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius is determined. aver_仿真 ;

[0013] According to σ A'_仿真 , σ aver_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 The fatigue limit of the target foreign object damaged blade along the length direction of the blade at the dangerous point at the root of the notch is calculated.

[0014] In one possible design, the utilization of σ A'_Mises_仿真 , σ B'_Mises_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Calculate the stress concentration factor corresponding to the target foreign object damaged blade, including:

[0015] σ A'_Mises_仿真 , σ B'_Mises_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真Substitute the set stress concentration factor formula for calculation to obtain the stress concentration factor corresponding to the target foreign object damaged blade. The stress concentration factor formula is:

[0016]

[0017] Among them, K t Characterizes the stress concentration factor.

[0018] In a possible design, the calculation of the critical distance of the dangerous point at the root of the notch using the notch depth, notch width and stress concentration factor corresponding to the blade damaged by the target foreign object includes:

[0019] Calling a preset critical distance fitting relationship, wherein the critical distance fitting relationship includes a functional relationship between the critical distance and the notch depth, notch width, and stress concentration factor;

[0020] The notch depth, notch width and stress concentration factor corresponding to the target foreign object damaged blade are substituted into the critical distance fitting formula for calculation to obtain the fitting critical distance of the dangerous point at the root of the notch of the target foreign object damaged blade.

[0021] In a possible design, before calling the preset critical distance fitting relationship, the method further includes:

[0022] Performing optical microscopic measurement on the macroscopic notch of the blade sample damaged by foreign objects to obtain its macroscopic damage geometric characteristic data, and performing CT scanning on the local micro-damage part of the macroscopic notch of the blade sample damaged by foreign objects to obtain its microscopic damage geometric characteristic data, wherein the material and specification of the blade sample damaged by foreign objects are the same as those of the target blade damaged by foreign objects;

[0023] A sample damage data model is constructed based on the macroscopic damage geometric feature data and microscopic damage geometric feature data of the blade sample damaged by foreign objects, and a complete blade data model corresponding to the blade sample damaged by foreign objects is constructed, and the complete blade data model is superimposed with the sample damage data model to obtain the sample damaged blade data model;

[0024] The first-order modal simulation of the damaged blade data model of the foreign object damaged blade specimen is carried out to determine its far-field point and the dangerous point at the root of the notch. The Mises stress σ at the far-field point is A'_Mises_试样 , and the Mises stress σ at the dangerous point at the root of the notch B'_Mises_试样 , the first-order modal simulation is performed on the complete blade data model of the foreign object damaged blade specimen to determine the Mises stress σ at the corresponding far-field point A_Mises_试样 And the Mises stress σ at the critical point at the root of the gap B_Mises_试样 ;

[0025] Using σ A'_Mises_试样 , σB'_Mises_试样 , σ A_Mises_试样 and σ B_Mises_试样 Calculate the stress concentration factor K corresponding to the blade specimen damaged by foreign objects t , based on the specimen damage data model, determine the notch depth a and notch width b corresponding to the blade specimen damaged by foreign objects;

[0026] Based on the first-order modal simulation results of the damaged blade data model, the critical distance r of the root danger point of the notch is determined. c ,in:

[0027] r c =1.54l0

[0028]

[0029] M is the set geometric correction coefficient, σ -1 is the fatigue strength of the given blade material, ΔK th is the set fatigue threshold stress intensity factor;

[0030] The stress concentration factor K corresponding to several blade specimens damaged by foreign objects is used t , gap depth a, gap width b and critical distance r of the dangerous point at the root of the gap c Perform polynomial fitting to obtain the critical distance fitting relationship.

[0031] In a possible design, the first-order modal simulation result based on the damaged blade data model determines the average stress σ in the area within the hemispherical range along the notch depth direction with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius. aver_仿真 ,include:

[0032] Determine the grid cells within the hemispherical range along the notch depth direction, with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius in the damaged blade data model, and use these grid cells as target grid cells;

[0033] Determine the absolute value of the maximum principal stress of each target grid unit, and take the average value of the absolute values ​​of the maximum principal stress of all target grid units as the average stress σ of the corresponding notch root danger point area aver_仿真 .

[0034] In one possible design, the A'_仿真 , σ aver_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Calculate the fatigue limit of the target foreign object damaged blade along the length direction of the blade at the dangerous point at the root of the notch, including:

[0035] σA'_仿真 , σ aver_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Substitute it into the preset fatigue limit prediction formula for calculation, and obtain the fatigue limit σ of the target foreign object damaged blade along the blade length direction at the dangerous point of the notch root B_测 , the fatigue limit prediction formula is:

[0036]

[0037] Among them, σ -1 is the fatigue strength of the given blade material.

[0038] In one possible design, the method further includes:

[0039] Perform optical microscopic measurement on the macroscopic notch of the blade verified by foreign object damage to obtain its macroscopic damage geometric characteristic data, and perform CT scanning on the local micro-damage part of the macroscopic notch of the blade verified by foreign object damage to obtain its microscopic damage geometric characteristic data;

[0040] A verification damage data model is constructed based on the macroscopic damage geometric feature data and microscopic damage geometric feature data of the blade damaged by foreign objects, and a verification complete blade data model corresponding to the verification foreign object damaged blade is constructed, and the verification complete blade data model is superimposed on the verification damage data model to obtain a verification damaged blade data model;

[0041] The first-order modal simulation is performed on the data model of the damaged blade to determine the far-field point and the dangerous point at the root of the notch. The modal stress σ at the far-field point along the length direction of the blade is A'_验证 , the Mises stress σ at the far-field point A'_Mises_验证 , and the Mises stress σ at the critical point at the root of the notch B'_Mises_验证 , perform the first-order modal simulation on the complete blade data model to determine the Mises stress σ at the corresponding far-field point A_Mises_验证 And the Mises stress σ at the critical point at the root of the gap B_Mises_验证 ;

[0042] Using σ A'_Mises_验证 , σ B'_Mises_验证 , σ A_Mises_验证 and σ B_Mises_验证 Calculate the stress concentration factor corresponding to the blade with foreign object damage, and determine the notch depth and notch width corresponding to the blade with foreign object damage based on the damage data model;

[0043] The fitting critical distance of the dangerous point at the root of the notch is calculated by verifying the notch depth, notch width and stress concentration factor corresponding to the blade damaged by foreign objects;

[0044] Based on the first-order modal simulation results of the damaged blade data model, the average stress σ in the hemispherical area along the notch depth direction is determined with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius. aver_验证 ;

[0045] σ aver_验证 , σ A'_验证 , σ A_Mises_验证 and σ B_Mises_验证 Substitute into the fatigue limit prediction formula and use σ aver_验证 Replace σ aver_仿真 , using σ A'_验证 Replace σ A'_仿真 , using σ A_Mises_验证 Replace σ A_Mises_仿真 , using σ B_Mises_验证 Replace σ B_Mises_仿真 , using σ B_验证 Replace σ B_验 , the verified fatigue limit σ of the blade damaged by foreign objects along the length direction of the blade at the dangerous point of the notch root is calculated B_验证 ;

[0046] The fatigue strength test of the blade with foreign object damage is carried out to determine the experimental fatigue limit σ of the blade with foreign object damage along the length direction at the dangerous point of the notch root. B_实验 ;

[0047] The experimental fatigue limit σ B_实验 To verify the fatigue limit σ B_验证 Verify the fatigue limit σ B_验证 and experimental fatigue limit σ B_实验 When the error between them meets the set error condition, the verification is judged to be successful.

[0048] In a second aspect, a fatigue strength prediction system for aero-engine foreign object damaged blades based on three-dimensional feature analysis of macro and micro damage is provided, comprising a geometry measurement unit, a model building unit, a modal simulation unit, a parameter determination unit, a fitting calculation unit, a stress determination unit and a limit estimation unit, wherein:

[0049] A geometric measurement unit is used to perform optical microscopic measurement on the macroscopic notch of the target foreign object damaged blade to obtain its macroscopic damage geometric characteristic data, and to perform CT scanning on the local micro-damage part of the macroscopic notch of the target foreign object damaged blade to obtain its microscopic damage geometric characteristic data;

[0050] A model building unit is used to build a damage data model based on the macro damage geometric feature data and micro damage geometric feature data of the target foreign object damaged blade, and to build a complete blade data model corresponding to the target foreign object damaged blade, and to superimpose the complete blade data model with the damage data model to obtain a damaged blade data model;

[0051] The modal simulation unit is used to perform first-order modal simulation on the damaged blade data model to determine its far-field point and the dangerous point at the root of the notch, and the modal stress σ at the far-field point along the length direction of the blade A'_仿真 , the Mises stress σ at the far-field point A'_Mises_仿真 , and the Mises stress σ at the critical point at the root of the notch B'_Mises_仿真 , perform first-order modal simulation on the complete blade data model to determine the Mises stress σ at the corresponding far-field point A_Mises_仿真 And the Mises stress σ at the critical point at the root of the gap B_Mises_仿真 ;

[0052] Parameter determination unit for utilizing σ A'_Mises_仿真 , σ B'_Mises_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Calculate the stress concentration factor corresponding to the target foreign object damaged blade, and determine the notch depth and notch width corresponding to the target foreign object damaged blade based on the damage data model;

[0053] A fitting calculation unit is used to calculate the fitting critical distance of the dangerous point at the root of the notch by using the notch depth, notch width and stress concentration factor corresponding to the blade damaged by the target foreign object;

[0054] The stress determination unit is used to determine the average stress σ in the hemispherical area along the notch depth direction with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius based on the first-order modal simulation results of the damaged blade data model. aver_仿真 ;

[0055] The limit estimation unit is used to calculate the A'_仿真 , σ aver_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 The fatigue limit of the target foreign object damaged blade along the length direction of the blade at the dangerous point at the root of the notch is calculated.

[0056] In a third aspect, a fatigue strength prediction system for aircraft engine foreign object damaged blades based on macro and micro damage three-dimensional feature analysis is provided, comprising:

[0057] A memory for storing instructions;

[0058] A processor is used to read the instructions stored in the memory and execute any one of the methods described in the first aspect according to the instructions.

[0059] In a fourth aspect, a computer-readable storage medium is provided, wherein instructions are stored on the computer-readable storage medium, and when the instructions are executed on a computer, the computer executes any one of the methods described in the first aspect. In addition, a computer program product is provided, and when the computer program product is executed on a computer, the computer executes any one of the methods described in the first aspect.

[0060] Beneficial effects: The present invention aims at the problem of high-cycle fatigue strength assessment of aircraft engine blades with foreign object damage, carries out high-precision scanning and reconstruction of the notch locally, reveals the macroscopic and microscopic damage characteristics of the notch, establishes an accurate high-cycle fatigue strength assessment model for blades with foreign object damage notches, and then uses the model to perform first-order modal simulation, uses the relevant parameters obtained by the simulation to analyze and calculate the high-cycle fatigue strength of blades with foreign object damage, and obtains effective fatigue strength prediction results for blades with foreign object damage. The present invention can accurately assess the fatigue strength of aircraft engine blades with foreign object damage notches, provides theoretical guidance for the exemption of repair or scrapping of blades, and has important scientific significance and engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0062] Figure 1 This is a schematic diagram of the steps of the method in Example 1 of the present invention;

[0063] Figure 2 Schematic diagram of the system structure in Example 3 of the present invention. DETAILED DESCRIPTION

[0064] It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. The specific structures and functional details disclosed herein are only used to describe the exemplary embodiments of the present invention. However, the present invention can be embodied in many alternative forms, and it should not be understood that the present invention is limited to the embodiments set forth herein.

[0065] It should be understood that unless otherwise clearly specified and limited, the corresponding terms should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments can be understood according to specific circumstances.

[0066] In the following description, certain details are provided to facilitate a complete understanding of the example embodiments. However, it will be appreciated by those of ordinary skill in the art that the example embodiments may be implemented without these certain details. For example, devices may be shown in block diagrams to avoid obscuring the examples with unnecessary details. In other embodiments, well-known processes, structures, and techniques may not be shown in unnecessary detail to avoid obscuring the embodiments.

[0067] Embodiment 1:

[0068] This embodiment provides a method for predicting fatigue strength of aircraft engine blades with foreign object damage based on three-dimensional feature analysis of macro and micro damage, which can be applied to corresponding evaluation systems, such as Figure 1 As shown, the method comprises the following steps:

[0069] S1. Perform optical microscopic measurement on the macroscopic notch of the target foreign object damaged blade to obtain its macroscopic damage geometric characteristic data, and perform CT scanning on the local micro-damaged part of the macroscopic notch of the target foreign object damaged blade to obtain its microscopic damage geometric characteristic data.

[0070] In specific implementation, the macroscopic notch of the target foreign object damaged blade can be optically measured by optical microscopic measurement equipment to obtain its macroscopic damage geometric feature data, and the measurement data can be exported as a .stl format file. The local micro-damage part of the macroscopic notch of the target foreign object damaged blade can be CT scanned by CT scanning equipment to obtain its microscopic damage geometric feature data, and the measurement data can be exported as a .stl format file.

[0071] S2. Construct a damage data model based on the macroscopic damage geometric feature data and microscopic damage geometric feature data of the target foreign object damaged blade, and construct a complete blade data model corresponding to the target foreign object damaged blade, and superimpose the complete blade data model with the damage data model to obtain a damaged blade data model.

[0072] In specific implementation, the .stl format file containing the macroscopic damage geometric feature data of the target foreign object damaged blade can be reversely reconstructed to obtain the .stp format file containing the corresponding macroscopic damage geometric feature data, and the .stl format file containing the microscopic damage geometric feature data of the target foreign object damaged blade can be reversely reconstructed to obtain the .stp format file containing the corresponding microscopic damage geometric feature data, and then the .stp format file corresponding to the macroscopic damage geometric feature data and the .stp format file corresponding to the microscopic damage geometric feature data are combined for modeling to generate the corresponding damage data model. At the same time, a complete blade data model corresponding to the target foreign object damaged blade can be constructed based on the external dimensions of the target foreign object damaged blade, that is, a complete blade model without a damage notch, and then the complete blade data model is superimposed on the damage data model to obtain a damaged blade data model.

[0073] S3. Perform first-order modal simulation on the damaged blade data model to determine its far-field point and the dangerous point at the root of the notch. The modal stress σ at the far-field point along the blade length direction A'_仿真 , the Mises stress σ at the far-field point A'_Mises_仿真 , and the Mises stress σ at the critical point at the root of the notch B'_Mises_仿真 , perform first-order modal simulation on the complete blade data model to determine the Mises stress σ at the corresponding far-field point A_Mises_仿真 And the Mises stress σ at the critical point at the root of the gap B_Mises_仿真 .

[0074] In specific implementation, the system can perform first-order modal simulation on the damaged blade data model and display the model simulation results. The user can select the far-field point A and the dangerous point B at the root of the notch according to the displayed model simulation results. The system determines the far-field point A and the dangerous point B at the root of the notch in response to the user's selection operation, and determines the modal stress σ at the far-field point A along the length direction of the blade based on the simulation results. A'_仿真 , Mises stress σ at far-field point A A'_Mises_仿真 , and the Mises stress σ at the dangerous point B at the root of the notch B'_Mises_仿真 At the same time, the system performs a first-order modal simulation on the complete blade data model to determine the Mises stress σ at the position corresponding to the far-field point A in the complete blade data model. A'_Mises_仿真 , and the Mises stress σ at the position of the dangerous point B at the root of the notch B'_Mises_仿真 .

[0075] S4. Using σ A'_Mises_仿真 , σ B'_Mises_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 The stress concentration factor corresponding to the target foreign object damaged blade is calculated, and the notch depth and notch width corresponding to the target foreign object damaged blade are determined based on the damage data model.

[0076] In specific implementation, the system will A'_Mises_仿真 , σ B'_Mises_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Substitute the set stress concentration factor formula for calculation to obtain the stress concentration factor corresponding to the target foreign object damaged blade. The stress concentration factor formula is:

[0077]

[0078] Among them, K t Characterize the stress concentration factor. At the same time, the system determines the notch depth and notch width corresponding to the target foreign object damaged blade based on the corresponding measured geometric feature data of the damage data model.

[0079] S5. Calculate the fitting critical distance of the dangerous point at the root of the notch using the notch depth, notch width and stress concentration factor corresponding to the blade damaged by the target foreign object.

[0080] During specific implementation, the system can call a preset critical distance fitting formula, which includes a functional relationship between the critical distance and the notch depth, notch width and stress concentration factor. The notch depth, notch width and stress concentration factor corresponding to the target foreign object damaged blade are then substituted into the critical distance fitting formula for calculation to obtain the fitting critical distance of the dangerous point at the root of the notch of the target foreign object damaged blade.

[0081] The critical distance fitting relational expression is a priori relational expression, which can be fitted in advance based on the test results of the foreign object damaged blade specimen of the same type as the foreign object damaged blade. The test process of the foreign object damaged blade specimen can refer to the above steps S1-S4 corresponding to the target foreign object damaged blade. Exemplarily, before calling the critical distance fitting relational expression, the process of determining the critical distance fitting relational expression may include the following steps S51-S56:

[0082] S51. Performing optical microscopic measurement of the macroscopic notch of the blade sample damaged by foreign objects to obtain its macroscopic damage geometric characteristic data, and performing CT scanning on the local micro-damage site of the macroscopic notch of the blade sample damaged by foreign objects to obtain its microscopic damage geometric characteristic data, wherein the material and specification of the blade sample damaged by foreign objects are the same as those of the target blade damaged by foreign objects;

[0083] S52. constructing a sample damage data model based on the macroscopic damage geometric feature data and microscopic damage geometric feature data of the blade sample damaged by foreign objects, and constructing a complete blade data model corresponding to the blade sample damaged by foreign objects, superimposing the complete blade data model with the sample damage data model to obtain the sample damage blade data model;

[0084] S53. Perform first-order modal simulation on the blade damage data model of the blade damage specimen, determine its far-field point and the dangerous point at the root of the notch, and the Mises stress σ at its far-field point A'_Mises_试样 , and the Mises stress σ at the dangerous point at the root of the notch B'_Mises_试样 , the first-order modal simulation is performed on the complete blade data model of the foreign object damaged blade specimen to determine the Mises stress σ at the corresponding far-field point A_Mises_试样 And the Mises stress σ at the critical point at the root of the gap B_Mises_试样 ;

[0085] S54. Using σ A'_Mises_试样 , σ B'_Mises_试样 , σ A_Mises_试样 and σ B_Mises_试样 Calculate the stress concentration factor K corresponding to the blade specimen damaged by foreign objects t , based on the specimen damage data model, determine the notch depth a and notch width b corresponding to the blade specimen damaged by foreign objects;

[0086] S55. Based on the first-order modal simulation results of the damaged blade data model, determine the critical distance r of the root danger point of the notch c ,in:

[0087] r c =1.54l0

[0088]

[0089] M is the set geometric correction coefficient, σ -1 is the fatigue strength of the given blade material, ΔK th is the set fatigue threshold stress intensity factor;

[0090] S56. Stress concentration factor K corresponding to blade specimens damaged by several foreign objects t , gap depth a, gap width b and critical distance r of the dangerous point at the root of the gap c Perform polynomial fitting to obtain the critical distance fitting relationship r c =f(a, b, K t ). The critical distance fitting relationship is a relationship function obtained by polynomial fitting for the same type (i.e., the same material and specification) of foreign object damaged blade specimens. Different types of foreign object damaged blades correspond to different critical distance fitting relationships. The same type of foreign object damaged blade specimens can be selected for testing and fitting according to the type (i.e., material and specification) of the target foreign object damaged blade.

[0091] S6. Based on the first-order modal simulation results of the damaged blade data model, determine the average stress σ in the hemispherical area along the notch depth direction with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius. aver_仿真 .

[0092] In the specific implementation, the system first determines the grid cells in the damaged blade data model, with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius, within the hemispherical range along the notch depth direction, and uses these grid cells as target grid cells. Then, the maximum principal stress absolute value of each target grid cell is determined, and the average value of the maximum principal stress absolute values ​​of all target grid cells is used as the average stress σ corresponding to the notch root danger point area. aver_仿真 .

[0093] S7. According to σ A'_仿真 , σ aver_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 The fatigue limit of the target foreign object damaged blade along the length direction of the blade at the dangerous point at the root of the notch is calculated.

[0094] In specific implementation, the system will A'_仿真 , σ aver_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Substitute it into the preset fatigue limit prediction formula for calculation, and obtain the fatigue limit σ of the target foreign object damaged blade along the blade length direction at the dangerous point of the notch root B_测 , the fatigue limit prediction formula is:

[0095]

[0096] Among them, σ -1 is the fatigue strength of the given blade material.

[0097] Before the fatigue limit prediction formula is used to actually calculate the fatigue limit of the target foreign object damaged blade, it is necessary to undergo corresponding accuracy verification, that is, using a verification foreign object damaged blade of the same type as the target foreign object damaged blade to obtain the corresponding verification fatigue limit by referring to the above steps S1-S7, and then through the fatigue strength test of the verification foreign object damaged blade, the corresponding experimental fatigue limit is obtained, and by comparing the verification fatigue limit of the verification foreign object damaged blade with the experimental fatigue limit, it is determined whether the accuracy verification of the fatigue limit prediction formula has passed. The verification process is as follows: Steps S71-S79:

[0098] S71. Perform optical microscopic measurement on the macroscopic notch of the blade verified by foreign object damage to obtain its macroscopic damage geometric characteristic data, and perform CT scanning on the local micro-damage part of the macroscopic notch of the blade verified by foreign object damage to obtain its microscopic damage geometric characteristic data;

[0099] S72. Constructing a verification damage data model based on the macroscopic damage geometric feature data and microscopic damage geometric feature data of the blade damaged by foreign objects, and constructing a verification complete blade data model corresponding to the blade damaged by foreign objects, superimposing the verification complete blade data model with the verification damage data model to obtain a verification damaged blade data model;

[0100] S73. Perform first-order modal simulation on the damaged blade data model to determine the far-field point and the dangerous point at the root of the notch. The modal stress σ at the far-field point along the blade length direction A'_验证 , the Mises stress σ at the far-field point A'_Mises_验证 , and the Mises stress σ at the critical point at the root of the notch B'_Mises_验证 , perform the first-order modal simulation on the complete blade data model to determine the Mises stress σ at the corresponding far-field point A_Mises_验证 And the Mises stress σ at the critical point at the root of the gap B_Mises_验证 ;

[0101] S74. Using σ A'_Mises_验证 , σ B'_Mises_验证 , σ A_Mises_验证 and σ B_Mises_验证 Calculate the stress concentration factor corresponding to the blade with foreign object damage, and determine the notch depth and notch width corresponding to the blade with foreign object damage based on the damage data model;

[0102] S75. Calculate the fitting critical distance of the dangerous point at the root of the notch by using the notch depth, notch width and stress concentration factor corresponding to the blade damaged by the foreign object;

[0103] S76. Based on the first-order modal simulation results of the damaged blade data model, determine the average stress σ in the hemispherical area along the notch depth direction with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius. aver_验证 ;

[0104] S77. aver_验证 , σ A'_验证 , σ A_Mises_验证 and σ B_Mises_验证 Substitute into the fatigue limit prediction formula and use σ aver_验证 Replace σ aver_仿真 , using σ A'_验证 Replace σ A'_仿真 , using σ A_Mises_验证 Replace σ A_Mises_仿真 , using σB_Mises_验证 Replace σ B_Mises_仿真 , using σ B_验证 Replace σ B_验 , the verified fatigue limit σ of the blade damaged by foreign objects along the length direction of the blade at the dangerous point of the notch root is calculated B_验证 ;

[0105] S78. Perform fatigue strength test on the blades with foreign object damage to determine the experimental fatigue limit σ of the blades with foreign object damage at the dangerous point of the notch root along the length direction of the blade. B_实验 ;

[0106] S79. Using experimental fatigue limit σ B_实验 To verify the fatigue limit σ B_验证 Verify the fatigue limit σ B_验证 and experimental fatigue limit σ B_实验 When the error between them meets the set error condition, the verification is judged to be successful.

[0107] Embodiment 2:

[0108] This embodiment provides a fatigue strength prediction system for aero-engine foreign object damaged blades based on macro-micro damage three-dimensional feature analysis, including a geometry measurement unit, a model building unit, a modal simulation unit, a parameter determination unit, a fitting calculation unit, a stress determination unit and a limit estimation unit, wherein:

[0109] A geometric measurement unit is used to perform optical microscopic measurement on the macroscopic notch of the target foreign object damaged blade to obtain its macroscopic damage geometric characteristic data, and to perform CT scanning on the local micro-damage part of the macroscopic notch of the target foreign object damaged blade to obtain its microscopic damage geometric characteristic data;

[0110] A model building unit is used to build a damage data model based on the macro damage geometric feature data and micro damage geometric feature data of the target foreign object damaged blade, and to build a complete blade data model corresponding to the target foreign object damaged blade, and to superimpose the complete blade data model with the damage data model to obtain a damaged blade data model;

[0111] The modal simulation unit is used to perform first-order modal simulation on the damaged blade data model to determine its far-field point and the dangerous point at the root of the notch, and the modal stress σ at the far-field point along the length direction of the blade A'_仿真 , the Mises stress σ at the far-field point A'_Mises_仿真 , and the Mises stress σ at the critical point at the root of the notch B'_Mises_仿真 , perform first-order modal simulation on the complete blade data model to determine the Mises stress σ at the corresponding far-field point A_Mises_仿真 And the Mises stress σ at the critical point at the root of the gap B_Mises_仿真 ;

[0112] Parameter determination unit for utilizing σ A'_Mises_仿真 , σ B'_Mises_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Calculate the stress concentration factor corresponding to the target foreign object damaged blade, and determine the notch depth and notch width corresponding to the target foreign object damaged blade based on the damage data model;

[0113] A fitting calculation unit is used to calculate the fitting critical distance of the dangerous point at the root of the notch by using the notch depth, notch width and stress concentration factor corresponding to the blade damaged by the target foreign object;

[0114] The stress determination unit is used to determine the average stress σ in the hemispherical area along the notch depth direction with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius based on the first-order modal simulation results of the damaged blade data model. aver_仿真 ;

[0115] The limit estimation unit is used to calculate the A'_仿真 , σ aver_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 The fatigue limit of the target foreign object damaged blade along the length direction of the blade at the dangerous point at the root of the notch is calculated.

[0116] Embodiment 3:

[0117] This embodiment provides a fatigue strength prediction system for aircraft engine foreign object damaged blades based on macro and micro damage three-dimensional feature analysis. Figure 2 As shown, at the hardware level, it includes:

[0118] Data interface, used to establish data connection between the processor and the external data terminal;

[0119] A memory for storing instructions;

[0120] The processor is used to read the instructions stored in the memory and execute the fatigue strength prediction method of the aircraft engine foreign object damaged blade in Example 1 according to the instructions.

[0121] Optionally, the system further includes an internal bus, through which the processor, the memory and the data interface can be interconnected, and the internal bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc.

[0122] The memory may include, but is not limited to, random access memory (RAM), read only memory (ROM), flash memory, first input first output (FIFO) and / or first in last out (FILO), etc. The processor may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components.

[0123] Embodiment 4:

[0124] This embodiment provides a computer-readable storage medium, on which instructions are stored, and when the instructions are executed on a computer, the computer executes the method for predicting fatigue strength of aeroengine blades damaged by foreign objects in Embodiment 1. The computer-readable storage medium refers to a carrier for storing data, which may include but is not limited to a floppy disk, an optical disk, a hard disk, a flash memory, a USB flash drive, and / or a memory stick, etc., and the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.

[0125] This embodiment also provides a computer program product, which, when executed on a computer, executes the method for predicting fatigue strength of aero-engine foreign object damaged blades in Embodiment 1. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.

[0126] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fatigue strength prediction method for aircraft engine foreign object damaged blades based on three-dimensional feature analysis of macro and micro damage, characterized in that: include: Perform optical microscopic measurement on the macroscopic notch of the target foreign object damaged blade to obtain its macroscopic damage geometric characteristic data, and perform CT scanning on the local micro-damage part of the macroscopic notch of the target foreign object damaged blade to obtain its microscopic damage geometric characteristic data; A damage data model is constructed based on the macroscopic damage geometric feature data and the microscopic damage geometric feature data of the target foreign object damaged blade, and a complete blade data model corresponding to the target foreign object damaged blade is constructed, and the complete blade data model is superimposed on the damage data model to obtain a damaged blade data model; The first-order modal simulation of the damaged blade data model is performed to determine its far-field point and the dangerous point at the root of the notch. The modal stress σ at the far-field point along the length direction of the blade is A'_仿真 , the Mises stress σ at the far-field point A'_Mises_仿真 , and the Mises stress σ at the critical point at the root of the notch B'_Mises_仿真 , perform first-order modal simulation on the complete blade data model to determine the Mises stress σ at the corresponding far-field point A_Mises_仿真 And the Mises stress σ at the critical point at the root of the gap B_Mises_仿真 ; Using σ A'_Mises_仿真 , σ B'_Mises_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Calculate the stress concentration factor corresponding to the target foreign object damaged blade, and determine the notch depth and notch width corresponding to the target foreign object damaged blade based on the damage data model; The fitting critical distance of the dangerous point at the root of the notch is calculated using the notch depth, notch width and stress concentration factor corresponding to the blade damaged by the target foreign object; Based on the first-order modal simulation results of the damaged blade data model, the average stress σ in the hemispherical area along the notch depth direction with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius is determined. aver_仿真 ; According to σ A'_仿真 , σ aver_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 The fatigue limit of the target foreign object damaged blade along the length direction of the blade at the dangerous point at the root of the notch is calculated.

2. The fatigue strength prediction method of aero-engine foreign object damaged blades based on macro-micro damage three-dimensional feature analysis according to claim 1 is characterized in that: The use of σ A'_Mises_仿真 , σ B'_Mises_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Calculate the stress concentration factor corresponding to the target foreign object damaged blade, including: σ A'_Mises_仿真 , σ B'_Mises_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Substitute the set stress concentration factor formula for calculation to obtain the stress concentration factor corresponding to the target foreign object damaged blade. The stress concentration factor formula is: Among them, K t Characterizes the stress concentration factor.

3. The fatigue strength prediction method of aero-engine foreign object damaged blades based on macro-micro damage three-dimensional feature analysis according to claim 1 is characterized in that: The method of calculating the critical distance of the dangerous point at the root of the notch by using the notch depth, notch width and stress concentration factor corresponding to the blade damaged by the target foreign object comprises: Calling a preset critical distance fitting relationship, wherein the critical distance fitting relationship includes a functional relationship between the critical distance and the notch depth, notch width, and stress concentration factor; The notch depth, notch width and stress concentration factor corresponding to the target foreign object damaged blade are substituted into the critical distance fitting formula for calculation to obtain the fitting critical distance of the dangerous point at the root of the notch of the target foreign object damaged blade.

4. The fatigue strength prediction method of aero-engine foreign object damaged blades based on macro-micro damage three-dimensional feature analysis according to claim 3 is characterized in that: Before calling the preset critical distance fitting relationship, the method further includes: Performing optical microscopic measurement on the macroscopic notch of the blade sample damaged by foreign objects to obtain its macroscopic damage geometric characteristic data, and performing CT scanning on the local micro-damage part of the macroscopic notch of the blade sample damaged by foreign objects to obtain its microscopic damage geometric characteristic data, wherein the material and specification of the blade sample damaged by foreign objects are the same as those of the target blade damaged by foreign objects; A sample damage data model is constructed based on the macroscopic damage geometric feature data and microscopic damage geometric feature data of the blade sample damaged by foreign objects, and a complete blade data model corresponding to the blade sample damaged by foreign objects is constructed, and the complete blade data model is superimposed with the sample damage data model to obtain the sample damaged blade data model; The first-order modal simulation of the damaged blade data model of the foreign object damaged blade specimen is carried out to determine its far-field point and the dangerous point at the root of the notch. The Mises stress σ at the far-field point is A'_Mises_试样 , and the Mises stress σ at the dangerous point at the root of the notch B'_Mises_试样 , the first-order modal simulation is performed on the complete blade data model of the foreign object damaged blade specimen to determine the Mises stress σ at the corresponding far-field point A_Mises_试样 And the Mises stress σ at the critical point at the root of the gap B_Mises_试样 ; Using σ A'_Mises_试样 , σ B'_Mises_试样 , σ A_Mises_试样 and σ B_Mises_试样 Calculate the stress concentration factor K corresponding to the blade specimen damaged by foreign objects t , based on the specimen damage data model, determine the notch depth a and notch width b corresponding to the blade specimen damaged by foreign objects; Based on the first-order modal simulation results of the damaged blade data model, the critical distance r of the root danger point of the notch is determined. c ,in: r c ＝1.54l0 M is the set geometric correction coefficient, σ -1 is the fatigue strength of the given blade material, ΔK th is the set fatigue threshold stress intensity factor; The stress concentration factor K corresponding to several blade specimens damaged by foreign objects is used t , gap depth a, gap width b and critical distance r of the dangerous point at the root of the gap c Perform polynomial fitting to obtain the critical distance fitting relationship.

5. The fatigue strength prediction method of aero-engine foreign object damaged blades based on macro-micro damage three-dimensional feature analysis according to claim 1 is characterized in that: The first-order modal simulation results based on the damaged blade data model determine the average stress σ in the hemispherical area along the notch depth direction with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius. aver_仿真 ,include: Determine the grid cells within the hemispherical range along the notch depth direction, with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius in the damaged blade data model, and use these grid cells as target grid cells; Determine the absolute value of the maximum principal stress of each target grid unit, and take the average value of the absolute values ​​of the maximum principal stress of all target grid units as the average stress σ of the corresponding notch root danger point area aver_仿真 .

6. The fatigue strength prediction method of aero-engine foreign object damaged blades based on macro-micro damage three-dimensional feature analysis according to claim 1 is characterized in that: According to σ A'_仿真 , σ aver_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Calculate the fatigue limit of the target foreign object damaged blade along the length direction of the blade at the dangerous point at the root of the notch, including: σ A'_仿真 , σ aver_仿真 , σ A_Mises_仿真 and σ B_Mises_仿真 Substitute it into the preset fatigue limit prediction formula for calculation, and obtain the fatigue limit σ of the target foreign object damaged blade along the blade length direction at the dangerous point of the notch root B_测 , the fatigue limit prediction formula is: Among them, σ -1 is the fatigue strength of the given blade material.

7. The fatigue strength prediction method of aero-engine foreign object damaged blades based on macro-micro damage three-dimensional feature analysis according to claim 6 is characterized in that: The method further comprises: Perform optical microscopic measurement on the macroscopic notch of the blade verified by foreign object damage to obtain its macroscopic damage geometric characteristic data, and perform CT scanning on the local micro-damage part of the macroscopic notch of the blade verified by foreign object damage to obtain its microscopic damage geometric characteristic data; A verification damage data model is constructed based on the macroscopic damage geometric feature data and microscopic damage geometric feature data of the blade damaged by foreign objects, and a verification complete blade data model corresponding to the verification foreign object damaged blade is constructed, and the verification complete blade data model is superimposed on the verification damage data model to obtain a verification damaged blade data model; The first-order modal simulation is performed on the data model of the damaged blade to determine the far-field point and the dangerous point at the root of the notch. The modal stress σ at the far-field point along the length direction of the blade is A'_验证 , the Mises stress σ at the far-field point A'_Mises_验证 , and the Mises stress σ at the critical point at the root of the notch B'_Mises_验证 , perform the first-order modal simulation on the complete blade data model to determine the Mises stress σ at the corresponding far-field point A_Mises_验证 And the Mises stress σ at the critical point at the root of the gap B_Mises_验证 ; Using σ A'_Mises_验证 , σ B'_Mises_验证 , σ A_Mises_验证 and σ B_Mises_验证 Calculate the stress concentration factor corresponding to the blade with foreign object damage, and determine the notch depth and notch width corresponding to the blade with foreign object damage based on the damage data model; The fitting critical distance of the dangerous point at the root of the notch is calculated by verifying the notch depth, notch width and stress concentration factor corresponding to the blade damaged by foreign objects; Based on the first-order modal simulation results of the damaged blade data model, the average stress σ in the hemispherical area along the notch depth direction is determined with the notch root danger point as the center and the fitting critical distance of the notch root danger point as the radius. aver_验证 ; σ aver_验证 , σ A'_验证 , σ A_Mises_验证 and σ B_Mises_验证 Substitute into the fatigue limit prediction formula and use σ aver_验证 Replace σ aver_仿真 , using σ A'_验证 Replace σ A'_仿真 , using σ A_Mises_验证 Replace σ A_Mises_仿真 , using σ B_Mises_验证 Replace σ B_Mises_仿真 , using σ B_验证 Replace σ B_验 , the verified fatigue limit σ of the blade damaged by foreign objects along the length direction of the blade at the dangerous point of the notch root is calculated B_验证 ; The fatigue strength test of the blade with foreign object damage is carried out to determine the experimental fatigue limit σ of the blade with foreign object damage along the length direction at the dangerous point of the notch root. B_实验 ; The experimental fatigue limit σ B_实验 To verify the fatigue limit σ B_验证 Verify the fatigue limit σ B_验证 and experimental fatigue limit σ B_实验 When the error between them meets the set error condition, the verification is judged to be successful.

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