A method for simulating blade damage by coupling hard object impact and erosion tests

Abstract

This invention provides a blade damage simulation method coupled with hard object impact and corrosion testing, comprising the following steps: corrosion testing of a metal specimen and recording mass loss; calculating the average mass loss per unit surface area; obtaining a fitting equation between mass loss per unit surface area and corrosion time; using the fitting equation to calculate the corrosion time required to simulate real blade corrosion damage; conducting corrosion testing on the simulated blade; conducting a hard object impact test on the corroded simulated blade; and measuring and recording the size and surface morphology of the blade damage notch. Using a specimen of the same material as the real blade, a corrosion test is conducted to obtain a fitting equation between corrosion time and mass loss per unit surface area. Based on the mass loss per unit surface area of ​​the real blade, the required corrosion time is obtained, resulting in a simulated blade with the same degree of corrosion as the real blade. A hard object impact test is then conducted on the simulated blade using an air gun testing system to obtain a simulated blade after hard object impact that more closely approximates real operating conditions.

Description

Technical Field

[0001] This invention relates to the field of aero-engine blade technology, and specifically to a blade damage simulation method that couples hard object impact and corrosion testing. Background Technology

[0002] Aircraft engines may be damaged by hard external objects under service conditions. These objects include screws, hail, gravel, sand, etc. Damage can affect critical engine components, such as blades and turbines, leading to decreased engine performance or even failure. External object damage is one of the major hidden dangers to aircraft safety. Some standards refer to damage caused by hard objects such as metal and gravel impacting the engine as "Foreign Object Damage" (FOD).

[0003] To ensure that engines in service can continue to operate normally for a period of time after experiencing various types of damage, the material parameters and blade profile of the blades must be guaranteed to meet fatigue limits after damage during the initial design phase. Since blades in service may suffer random damage, and the relative velocity between the hard object and the blade is very high, it is necessary to seek methods to more realistically simulate the severe consequences of hard objects damaging the blades under laboratory conditions. At the same time, the conditions of the blades in service in real-world operating environments, such as the effects of oxidation and corrosion, must also be considered. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a method for simulating blade damage by accurately simulating hard object impact and corrosion tests coupled under laboratory conditions.

[0005] Technical solution: A blade damage simulation method coupling hard object impact and corrosion testing, comprising the following steps:

[0006] (1) Immerse multiple metal specimens made of the same material as real blades in a corrosion solution and keep them at a constant temperature, and record the mass loss at different corrosion times;

[0007] (2) Calculate the average mass loss per unit surface area of ​​each metal specimen under the same corrosion time;

[0008] (3) Using the corrosion time and the mean mass loss per unit surface area, the corresponding fitting equation is obtained;

[0009] (4) Measure the mass loss per unit surface area of ​​the real blade and calculate the required corrosion time using the fitting equation.

[0010] (5) Based on the corrosion time in step (4), the simulated blade is immersed in the corrosion solution to conduct a corrosion simulation test;

[0011] (6) The simulated blade after corrosion in step (5) is fixed in the air gun test system using a holding device, the hard object impact position is set, and a hard object damage test is carried out.

[0012] (7) Measure and record the size and surface morphology of the blade damage notch.

[0013] Specifically, step (6) includes the following sub-steps:

[0014] (61) Fix the simulated blade on the holding device and rotate the holding device so that the leading edge of the simulated blade is at a predetermined incident angle with the barrel of the air gun test system.

[0015] (62) Insert the test hard object into the barrel, set the pressure value of the air gun test system, and control the air gun test system to push the hard object to impact the leading edge of the simulated blade.

[0016] Preferably, the cross-section of the aforementioned gun barrel is square.

[0017] Preferably, step (61) further includes: setting a point light source inside the barrel of the cannon to form a light spot at the muzzle of the cannon, and using the light spot to determine the impact position of the hard object.

[0018] Specifically, step (7) includes: measuring the width and depth of the damage notch using a three-dimensional stereomicroscope and taking pictures to record the damage morphology; and observing and recording the microscopic features of the damage notch using a scanning electron microscope.

[0019] Specifically, the fitting equation is:

[0020] Δm=a-be -ct

[0021] In the formula: Δm is the mass loss per unit surface area, e is the natural logarithm, t is the corrosion time, and a, b, and c are positive constants that are related to the composition and concentration of the corrosion solution and the composition of the specimen.

[0022] Specifically, step (5) also includes: using a super depth-of-field three-dimensional microscopy system to measure and record the depth of the etched simulated blade surface.

[0023] Specifically, the metal specimen is made of stainless steel, and in some embodiments, it is 13Cr15Ni4Mo stainless steel.

[0024] Specifically, the corrosive liquid contains Cl - In some embodiments, the corrosive solution is an aqueous solution of dilute HCl.

[0025] Beneficial effects: Compared with the prior art, the significant effect of the present invention is that by using a standard test piece with the same material as the real blade to conduct corrosion tests under laboratory conditions, a fitting equation between corrosion time and mass loss per unit surface area is obtained. Thus, based on the mass loss per unit surface area of ​​the real blade, the required corrosion time under laboratory conditions is obtained, thereby obtaining a simulated blade with the same degree of corrosion as the real blade under laboratory conditions. Furthermore, the simulated blade after corrosion is subjected to hard object impact tests using an air gun test system, resulting in a simulated blade after hard object impact that is closer to the actual working conditions. Attached Figure Description

[0026] Figure 1 This is a flowchart of the steps in Example 1, which simulates blade damage by coupling hard object impact and corrosion tests. Detailed Implementation

[0027] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] In this embodiment, the selected corrosion solution is a 3.5% HCl solution by mass. The materials used for the metal specimen and the simulated blade are 13Cr15Ni4Mo stainless steel, and the size of the metal specimen is 20mm×20mm×10mm.

[0030] Please refer to Figure 1 As shown, this embodiment provides a blade damage simulation method that couples hard object impact and corrosion testing. The method includes the following steps:

[0031] (1) Six stainless steel specimens were completely immersed in the corrosive solution and kept at a constant temperature of 40°C. The mass loss of each specimen was recorded at 24h, 72h, 120h, 192h and 240h.

[0032] (2) Calculate the mass loss per unit surface area Δm of each stainless steel specimen under the above corrosion time, that is, the ratio of mass loss to surface area, and calculate the average mass loss per unit surface area Δm of the 6 metal specimens under the same corrosion time, and obtain the data in Table 1 below.

[0033] Table 1

[0034]

[0035] (3) Using the corrosion time and the mean mass loss Δm per unit surface area, the corresponding fitting equation is obtained:

[0036]

[0037] In the formula: Δm is the mass loss per unit surface area, and t is the corrosion time.

[0038] (4) Measure the mass loss per unit surface area Δm of the actual blade and calculate the required corrosion time using the above fitting equation.

[0039] (5) Based on the corrosion time in step (4), the simulated blades are immersed in the corrosion solution to conduct a corrosion simulation test, and multiple simulated blades with the same degree of corrosion as the real blades are obtained. The depth of the surface of the simulated blades after corrosion is measured and recorded using a super depth-of-field three-dimensional microscopic system.

[0040] (6) Fix the simulated blade after corrosion in step (5) onto the air gun test system using a holding device, set the hard object impact position, and conduct a hard object damage test, specifically including the following steps:

[0041] (61) The simulated blade is fixed on the holding device by a clamp. In this embodiment, the clamp is a turntable clamp, which can rotate 360° in the horizontal and vertical directions respectively. The clamp is fixed on the three-coordinate moving platform of the holding device, so that it can move freely in three directions, allowing the simulated blade to be subjected to hard object impacts at various positions and angles.

[0042] The rotating turntable fixture is used to make the leading edge of the simulated blade and the barrel of the air gun test system form a predetermined incident angle. The three-coordinate moving platform is moved back and forth along the barrel direction so that the distance between the leading edge and the muzzle is 2-3 cm, leaving aiming space. A point light source is set in the barrel to form a light spot at the muzzle. The center of the light spot is the impact position of the foreign object. The three-coordinate moving platform is moved so that the preset impact position is at the center of the light spot.

[0043] In this embodiment, the air gun barrel adopts a square barrel and a square sabot, which are different from those used in conventional tests, in order to control the flight attitude of irregular hard objects and achieve precise control of the hard object damage test.

[0044] (62) The test hard object is loaded into the barrel of the gun, the cylinder pressure is preset using the control system software, and the air gun test system is controlled to push the hard object to accelerate and impact the leading edge of the simulated blade to cause impact damage.

[0045] (7) Using a three-dimensional stereomicroscope, adjust the magnification (50 / 100 times) according to the microscope's field of view to measure the width and depth of the damage notch and take pictures to record the damage morphology; use a scanning electron microscope to observe and record the microscopic features of the damage notch to provide data support for further analysis.

Claims

1. A method for simulating blade damage by coupling hard object impact and corrosion testing, characterized in that, Includes the following steps: (1) Immerse multiple metal specimens made of the same material as real blades in a corrosion solution and keep them at a constant temperature, and record the mass loss at different corrosion times; (2) Calculate the average mass loss per unit surface area of ​​each metal specimen under the same corrosion time; (3) Using the corrosion time and the mean mass loss per unit surface area, the corresponding fitting equation is obtained; (4) Measure the mass loss per unit surface area of ​​the real blade and calculate the required corrosion time using the fitting equation. (5) Based on the corrosion time in step (4), the simulated blade is immersed in the corrosion solution to conduct a corrosion simulation test; (6) The simulated blade after corrosion in step (5) is fixed in the air gun test system using a holding device, the hard object impact position is set, and a hard object damage test is carried out. (7) Measure and record the size and surface morphology of the blade damage notch.

2. The blade damage simulation method according to claim 1, characterized in that: Step (6) includes the following sub-steps: (61) Fix the simulated blade on the holding device and rotate the holding device so that the leading edge of the simulated blade is at a predetermined incident angle with the barrel of the air gun test system. (62) Insert the test hard object into the gun barrel, set the pressure value of the air gun test system, and control the air gun test system to push the hard object to impact the leading edge of the simulated blade.

3. The blade damage simulation method according to claim 2, characterized in that: The cross-section of the gun barrel is square.

4. The blade damage simulation method according to claim 2, characterized in that: The step (61) further includes: setting a point light source inside the barrel of the cannon to form a light spot at the muzzle of the cannon, and using the light spot to determine the impact position of the hard object.

5. The blade damage simulation method according to claim 1, characterized in that: Step (7) includes: measuring the width and depth of the damage notch using a three-dimensional stereomicroscope and taking pictures to record the damage morphology; and observing and recording the microscopic features of the damage notch using a scanning electron microscope.

6. The blade damage simulation method according to claim 1, characterized in that: The fitting equation is: Δm=a-be -ct In the formula: Δm is the mass loss per unit surface area, e is the natural logarithm, t is the corrosion time, and a, b, and c are positive constants.

7. The blade damage simulation method according to claim 1, characterized in that: Step (5) further includes: using a super depth-of-field three-dimensional microscopy system to measure and record the depth of the corroded simulated blade surface.

8. The blade damage simulation method according to claim 1, characterized in that: The metal specimen is made of stainless steel.

9. The blade damage simulation method according to claim 1, characterized in that: The corrosive solution is an aqueous solution containing Cl-.

10. The blade damage simulation method according to claim 9, characterized in that: The corrosive solution is a dilute HCl solution.

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