CN115165381A - Design method of large-size fan rotor blade vibration fatigue test piece - Google Patents

Design method of large-size fan rotor blade vibration fatigue test piece Download PDF

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Publication number
CN115165381A
CN115165381A CN202210919453.9A CN202210919453A CN115165381A CN 115165381 A CN115165381 A CN 115165381A CN 202210919453 A CN202210919453 A CN 202210919453A CN 115165381 A CN115165381 A CN 115165381A
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China
Prior art keywords
fan rotor
rotor blade
blade
test piece
vibration
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CN202210919453.9A
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Chinese (zh)
Inventor
沈锡钢
苏守丽
刘一雄
邵帅
伊锋
于连超
韩方军
储建恒
王相平
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AECC Shenyang Engine Research Institute
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AECC Shenyang Engine Research Institute
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M15/00—Testing of engines
    • G01M15/14—Testing gas-turbine engines or jet-propulsion engines
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M7/00—Vibration-testing of structures; Shock-testing of structures
    • G01M7/02—Vibration-testing by means of a shake table
    • G01M7/022—Vibration control arrangements, e.g. for generating random vibrations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M7/00—Vibration-testing of structures; Shock-testing of structures
    • G01M7/02—Vibration-testing by means of a shake table
    • G01M7/025—Measuring arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
    • G01N3/34—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces generated by mechanical means, e.g. hammer blows
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0073—Fatigue

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Combustion & Propulsion (AREA)
  • Engineering & Computer Science (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

The application provides a design method of a large-size fan rotor blade vibration fatigue test piece, which comprises the following steps: carrying out modal analysis of the large-size fan rotor blade in a test and a working state to obtain the vibration characteristic of the large-size fan rotor blade; determining a resonance dangerous part of the fan rotor blade according to the static strength calculation result, the vibration characteristic and the whole machine dynamic stress test result of the fan rotor blade; the method comprises the following steps that a truncated fan rotor blade is truncated to obtain a truncated blade test piece containing a resonance danger part, and the truncated blade test piece and the fan rotor blade have the same or similar stress distribution; determining vibration fatigue test parameters of the truncated blade test piece; developing a vibration fatigue test of the test piece with the shortened blade, verifying whether the crack part is positioned at the checked resonance dangerous part, and completing the shortening design of the test piece if the crack is positioned at the checked resonance dangerous part; and if the crack is positioned at the non-examined resonance dangerous part, adjusting the truncation position until the requirement is met.

Description

Design method of large-size fan rotor blade vibration fatigue test piece
Technical Field
The application belongs to the technical field of aero-engines, and particularly relates to a design method of a large-size fan rotor blade vibration fatigue test piece.
Background
The large-size fan rotor blade with the shoulder is the titanium alloy rotor blade for aviation with the largest size, the strictest performance requirement and the largest technical difficulty in China at present, is mainly applied to an aircraft engine with a large bypass ratio, and the design of high cycle fatigue resistance of the large-size fan rotor blade is one of key factors. Meanwhile, in order to meet the design requirements of the engine on long service life and high reliability, a vibration fatigue test of the large-size fan blades needs to be carried out so as to know and master the difference between the fatigue strengths of the fan rotor component and the test piece, test the stability of the process, obtain the fatigue performance of the fan blades and verify whether the large-size fan blades can meet the design requirements of high cycle fatigue.
In a conventional blade vibration fatigue test, a full-size blade is usually adopted, however, the excitation energy of a conventional test bed cannot meet the requirement because the size of a large-size fan blade is much larger than that of the conventional blade, a large-thrust test bed needs to be purchased, and meanwhile, the vibration fatigue test of the large-size fan blade easily causes the failure of a non-examined part in advance, so that the verification of the examined part is insufficient, and the test period is prolonged.
Disclosure of Invention
The application aims to provide a design method of a large-size fan rotor blade vibration fatigue test piece, and the effectiveness of a test is guaranteed and the test cost is saved by reasonably intercepting large-size fan blades to form the test piece.
The technical scheme of the application is as follows: a design method of a large-size fan rotor blade vibration fatigue test piece comprises the following steps:
carrying out modal analysis of the large-size fan rotor blade in a test and working state to obtain the vibration characteristic of the large-size fan rotor blade;
according to the static strength calculation result, the vibration characteristic and the whole dynamic stress test result of the large-size fan rotor blade, determining the resonance dangerous part of the large-size fan rotor blade;
truncating the large-size fan rotor blade to obtain a truncated blade test piece containing the resonance danger part, wherein the truncated blade test piece and the large-size fan rotor blade have the same or similar stress distribution;
determining vibration fatigue test parameters of the truncated blade test piece, wherein the test parameters comprise an initial vibration load and a strain gauge bonding position;
carrying out a vibration fatigue test of the truncated blade test piece, verifying whether the crack part is positioned at the checked resonance dangerous part or not, and completing the truncation design of the truncated test piece if the crack is positioned at the checked resonance dangerous part; and if the crack is positioned at the non-examined resonance dangerous part, adjusting the truncation position until the requirement is met.
Further, the resonance danger part comprises a blade root.
Further, a lower half part test piece of the blade, which comprises a dangerous resonance part of the root of the blade body, is obtained by cutting along the profile direction or the horizontal direction of the blade body.
Further, when the large fan rotor blade has a shoulder, the resonance danger zone further includes a shoulder root.
Furthermore, the shoulder upper half part test piece containing the dangerous resonance part of the shoulder root is obtained by cutting along the horizontal direction at the lower side of the shoulder.
Further, the test initial load is determined by the following formula:
σ a = A·σ b
in the formula, σ a To test the initial load, σ b The ultimate strength of the material of the large-size fan rotor blade is A, and the A is a load coefficient.
Furthermore, the value of the load coefficient A is between 0.5 and 0.8.
Further, the bonding position of the strain gauge is obtained by converting the position of the maximum vibration stress, wherein the vibration stress of the strain gauge at the bonding position and the maximum vibration stress satisfy the following conditions:
σ= B·σ max
where σ is the vibration stress at the position where the strain gauge is attached, and σ max Maximum vibration stress of the blade, B is sigma and sigma max The ratio of the vibrational stresses.
Furthermore, the vibration stress ratio B is between 0.1 and 0.5.
The design method of the large-size fan rotor blade vibration fatigue test piece can guarantee effectiveness of the test, greatly shortens test period, is not limited by test equipment, is high in operability, and reduces test cost.
Drawings
In order to more clearly illustrate the technical solutions provided by the present application, the following briefly introduces the accompanying drawings. It is to be expressly understood that the drawings described below are only illustrative of some embodiments of the invention.
FIG. 1 is a flow chart of a design method of a large-sized fan rotor blade vibration fatigue test piece according to the present application.
FIG. 2a is a schematic diagram of the positions of a first cut-off line and a second cut-off line according to an embodiment of the present application.
FIG. 2b is a schematic diagram of the positions of a first truncation line and a second truncation line according to another embodiment of the present application.
Detailed Description
In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the drawings in the embodiments of the present application.
In order to carry out vibration fatigue test on large-size fan rotor blades on a conventional test bed, the application provides a design method of a large-size fan rotor blade vibration fatigue test piece, and the purpose of checking the fatigue performance of each key part is achieved by reasonably truncating the blades. The method can ensure that cracks appear at the examined parts at first, can obtain the fatigue performance of a plurality of examined parts, can shorten the test period, can reduce the test cost, and provides effective support for the high cycle fatigue resistance design of the large-size fan rotor blade.
As shown in FIG. 1, the present application provides a schematic flow chart of a method for designing a large-sized fan rotor blade vibration fatigue test piece, which comprises the following steps:
s1, analyzing vibration characteristics of large-size fan rotor blade
And carrying out modal analysis on the full-size fan rotor blade in the test and working states, obtaining the vibration characteristics of the blade, including vibration frequency and relative vibration stress distribution, and providing a basis for determining an examined part in a vibration fatigue test.
S2, determining the assessment part of the vibration fatigue test
And obtaining the resonance dangerous part of the blade by drawing a Goodman diagram based on the dynamic strength storage result according to the static strength calculation result, the vibration characteristic result and the whole machine dynamic stress test result of the blade.
In general, for a large-sized shrouded fan rotor blade, the shrouded root is a resonance hazard in addition to the blade root of interest, and therefore the shrouded large-sized fan rotor blade is examined at the blade root and the shrouded root.
S3, shortening fatigue test pieces for large-size fan rotor blades
The core of the blade truncation is that the self vibration characteristic of the blade is changed through the truncation blade so as to ensure that the checking part firstly cracks in the test period, and the truncation scheme of the test piece is finally determined through repeated iteration of numerical simulation analysis in the truncation process:
s31, as shown in figures 2a and 2b, in order to ensure that the checking parts of the root part of the convex shoulder and the root part of the blade body can obtain fatigue strength checking, in the application, the convex shoulder J1 and the tenon J2 are respectively used as test clamping parts, the lower part of the convex shoulder J1 is truncated by adopting a first truncation short line X1, and the large-size fan rotor blade is divided into a part 11 above the convex shoulder and a lower half part 12 of the blade body.
S32, regarding the dimension L of the position 11 above the convex shoulder, after the truncated, the convex shoulder J1 can be regarded as a fixed support, and finite element simulation analysis is carried out to ensure that the stress distribution of the position 11 above the truncated convex shoulder can simulate the resonance condition of the position of the convex shoulder when the large-size fan rotor blade is in the working state, and the two parts have the same or similar resonance frequencies.
S33, regarding the size of the lower half part 12 of the blade body, the lower half part 12 of the blade body may be further truncated by the second truncation line X2. During truncation, the stress distribution and the frequency characteristic of the root part of the blade body need to be comprehensively considered, the position of the maximum stress point is firstly ensured to be positioned at the root part of the blade body needing to be checked, and the vibration frequency and the maximum amplitude increasing frequency of the truncated blade are ensured to be optimal in the shortest test period.
In the present application, the second truncation line X2 may be truncated along the blade profile direction or may be truncated in a horizontal direction. As shown in fig. 2a, a second cut-off line X2 may be cut along the blade profile direction, and is substantially parallel to the blade root; the second truncated line X2 is cut horizontally as shown in fig. 2b, and is parallel to the first truncated line X1.
And S34, in order to improve the test efficiency, the lower half part 12 of the blade body can be truncated for multiple times by repeating the step c until the optimal lower half part 12 of the blade body is obtained.
S4, determining vibration fatigue test parameters
For the vibration fatigue test parameters of the truncated large-size fan rotor blade, the initial load and the sticking position of the strain gauge are mainly determined.
For test initial load: the large-size fan rotor blade is made of titanium alloy, the fatigue performance of a blade component is not clear, and meanwhile, the fatigue strength of the blade component and a pressure test piece is greatly different, so that reasonable initial load must be given to ensure the effectiveness of the test.
In the present application, the initial load of the test is determined by the following formula:
σ a = A·σ b
in the formula, σ a To test the initial load, σ b For the ultimate strength of the blade material, A is a load coefficient, and the load coefficient A is usually between 0.5 and 0.8 and is determined according to the material property and the size of the blade component.
For the strain gauge attachment position: generally speaking, the strain gauge can be adhered to any part of the blade body during the vibration fatigue test and is adhered to the maximum position of the vibration stress as much as possible, but the strain gauge cannot be adhered to a part of the examined part due to the complicated shape of the large-size fan rotor blade.
Therefore, the following method is adopted in the present application to determine the patch position:
σ= B·σ max
where σ is the vibration stress at the position where the strain gauge is attached, and σ max Maximum vibration stress of the blade, B is sigma and sigma max And the vibration stress ratio ensures that the vibration stress conversion is more accurate by controlling the proportional relation between the sticking position and the maximum vibration stress. The ratio B needs to be controlled within a certain range, usually between 0.1 and 0.5, and needs to be determined according to the whole machine dynamic measurement result and the similar structure fatigue result.
S5, carrying out vibration stress test and vibration fatigue test verification on the truncated blade
In order to ensure that the test achieves the expected effect, firstly, a vibration stress distribution test of the test piece at the upper part of the shoulder and the test piece at the lower part of the blade body is carried out, and the maximum stress position of each part is determined and verified. And calibrating according to the position, developing a vibration fatigue test of the test piece, and verifying whether the crack part is positioned at the checking part of the shoulder root and the blade body root. If the vibration fatigue test fracture positions of the truncated upper half part of the shoulder test piece and the truncated lower half part of the blade body test piece are corresponding check parts respectively, the test piece truncation design is completed; if the fracture position of the vibration fatigue test is a non-checking part, then carrying out truncation scheme design, and adjusting the positions of the first truncation line and the second truncation line until the requirements are met.
The design method of the large-size fan rotor blade vibration fatigue test piece can guarantee effectiveness of the test, greatly shortens test period, is not limited by test equipment, is high in operability, and reduces test cost.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (9)

1. A design method for a large-size fan rotor blade vibration fatigue test piece is characterized by comprising the following steps:
carrying out modal analysis of the large-size fan rotor blade in a test and working state to obtain the vibration characteristic of the large-size fan rotor blade;
according to the static strength calculation result, the vibration characteristic and the whole machine dynamic stress test result of the large-size fan rotor blade, determining a resonance dangerous part of the large-size fan rotor blade;
truncating the large-size fan rotor blade to obtain a truncated blade test piece containing the resonance danger part, wherein the truncated blade test piece and the large-size fan rotor blade have the same or similar stress distribution;
determining vibration fatigue test parameters of the truncated blade test piece, wherein the test parameters comprise an initial vibration load and a strain gauge bonding position;
developing a vibration fatigue test of the test piece with the shortened blade, verifying whether the crack part is positioned at the checked resonance dangerous part, and completing the shortening design of the test piece with the shortened blade if the crack is positioned at the checked resonance dangerous part; and if the crack is positioned at the non-examined resonance dangerous part, adjusting the truncation position until the requirement is met.
2. The method of claim 1, wherein the resonance risk portion comprises a blade root portion.
3. The method for designing a vibration fatigue test piece of a large-sized fan rotor blade as claimed in claim 2, wherein the lower half portion test piece of the blade including the dangerous resonance portion of the root portion of the blade body is obtained by cutting along the blade body profile direction or the horizontal direction.
4. The method of designing a large size fan rotor blade vibration fatigue test article of claim 2, wherein when the large size fan rotor blade has a shoulder, the resonance danger zone further comprises a shoulder root.
5. A design method of a large size fan rotor blade vibration fatigue test piece according to claim 4, wherein the shoulder upper half test piece containing the shoulder root dangerous resonance part is obtained by cutting along the horizontal direction at the lower side of the shoulder.
6. A design method of a large size fan rotor blade vibration fatigue test piece according to claim 3 or 5, wherein the test initial load is determined by the following formula:
σ a = A·σ b
in the formula, σ a To test the initial load, σ b The ultimate strength of the material of the large-size fan rotor blade is A, and the A is a load coefficient.
7. The method for designing a large-sized fan rotor blade vibration fatigue test piece according to claim 6, wherein the value of the load coefficient A is between 0.5 and 0.8.
8. The method for designing a large-sized fan rotor blade vibration fatigue test piece according to claim 6, wherein the bonding position of the strain gauge is converted from a maximum vibration stress position, and the vibration stress of the strain gauge at the bonding position and the maximum vibration stress satisfy:
σ= B·σ max
where σ is the vibration stress at the position where the strain gauge is attached, and σ max Maximum vibration stress of the blade, B is sigma and sigma max The ratio of the vibrational stresses.
9. The method for designing a large size fan rotor blade vibration fatigue test piece according to claim 8, wherein the vibration stress ratio B is between 0.1 and 0.5.
CN202210919453.9A 2022-08-02 2022-08-02 Design method of large-size fan rotor blade vibration fatigue test piece Pending CN115165381A (en)

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Application Number Priority Date Filing Date Title
CN202210919453.9A CN115165381A (en) 2022-08-02 2022-08-02 Design method of large-size fan rotor blade vibration fatigue test piece

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210919453.9A CN115165381A (en) 2022-08-02 2022-08-02 Design method of large-size fan rotor blade vibration fatigue test piece

Publications (1)

Publication Number Publication Date
CN115165381A true CN115165381A (en) 2022-10-11

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Application Number Title Priority Date Filing Date
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