Fan blade high-low cycle composite fatigue test excitation system and method

Abstract

The application provides a fan blade high-low cycle composite fatigue test excitation system and method. The system comprises: a rotating test table arranged in a vacuum chamber and used to drive the fan blade to rotate in the vacuum chamber; at least one actuator installed on the fan blade; a driving circuit connected with the at least one actuator; and a control device used to control the driving circuit to drive the at least one actuator to vibrate. The application can realize the mutual non-interference of low cycle load and high cycle load acting on the fan blade simultaneously.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, and in particular to a vibration excitation system and method for high- and low-cycle combined fatigue testing of fan blades. Background Technology

[0002] As the most prominent component of a high-bypass turbofan engine, the fan blade is susceptible to fatigue fracture, a common type of engine failure. Fan blade fracture directly impacts aircraft performance and can even jeopardize flight safety. During takeoff, cruise, and landing, the fan blade is simultaneously subjected to large-amplitude, low-frequency low-cycle loads caused by centrifugal force, and high-frequency, small-amplitude vibration loads caused by system vibrations and transient airflow disturbances. The combined effect of these two loads on the fan blade is neither purely low-cycle fatigue nor purely high-cycle fatigue, but rather a combination of both. Therefore, using only high-cycle or low-cycle fatigue as the basis for strength design and life estimation cannot effectively reflect the damage process of the blade during actual operation; a combination of high- and low-cycle fatigue must be used as the basis for strength design and life estimation.

[0003] The airworthiness regulations for civil aircraft engines clearly stipulate that life assessment must include the combined effects of high-cycle fatigue and low-cycle fatigue, and blade fatigue test results are the primary basis for determining blade life. Since it is difficult to accurately simulate the combined stress environment of high-cycle and low-cycle fatigue on fan blades in a real engine environment, there is an urgent need for an excitation method that can flexibly simulate the real working environment of blades. This method should provide the blades with excitation loads that vary with space and time, and these excitation loads should be independent of the blade rotational speed and unaffected by the blade rotational speed.

[0004] Currently, the challenges in high-cycle and low-cycle combined fatigue testing and measurement technology have been largely resolved. In terms of excitation technology, oil or gas is generally used as the excitation medium to apply periodic excitation to rotating blades, thereby achieving the testing objective of vibrating fan blades. However, this method leads to the coupling of high-cycle load and blade rotation speed. Applying gas or liquid excitation to the blades disrupts the original vacuum environment, causing speed fluctuations, which in turn affect the actual load. Therefore, how to effectively apply low-cycle and high-cycle loads simultaneously to the fan blades without interference is a pressing problem that needs to be solved. Summary of the Invention

[0005] To address the problem of mutual interference when low-cycle and high-cycle loads are applied simultaneously to fan blades, this invention provides a vibration excitation system and method for combined high- and low-cycle fatigue testing of fan blades.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a vibration excitation system for high- and low-cycle combined fatigue testing of fan blades, comprising:

[0008] A rotating test bench installed inside the vacuum chamber is used to drive the fan blades to rotate inside the vacuum chamber.

[0009] At least one actuator is mounted on the fan blade;

[0010] A drive circuit, connected to the at least one actuator; and

[0011] A control device for controlling the drive circuit to drive the at least one actuator to vibrate.

[0012] In a preferred embodiment of the present invention, the system further includes:

[0013] A vibration sensor installed on the fan blade is used to detect the real-time vibration signal of the fan blade and feed the real-time vibration signal back to the control device, so that the control device controls the drive circuit based on the real-time vibration signal.

[0014] In a preferred embodiment of the present invention, the system further includes:

[0015] A data acquisition device is used to acquire the real-time vibration signal detected by the vibration sensor and feed the real-time vibration signal back to the control device.

[0016] In a preferred embodiment of the present invention, the driving circuit includes:

[0017] A signal conversion module is used to convert the control signals output by the control device into corresponding digital signals;

[0018] An analog signal generator is used to convert the digital signal into a corresponding analog signal;

[0019] A power amplifier is used to amplify the analog signal and send it to the at least one actuator.

[0020] In a preferred embodiment of the present invention, the drive circuit is connected to the at least one actuator via a slip ring.

[0021] In a preferred embodiment of the invention, the actuator is made of a piezoelectric material.

[0022] Secondly, the present invention provides a vibration excitation method for high- and low-cycle combined fatigue testing of fan blades, based on the aforementioned vibration system, the method comprising:

[0023] The control device outputs a control signal to the drive circuit, so that the drive circuit drives the at least one actuator to vibrate according to the control signal.

[0024] In a preferred embodiment of the present invention, the method further includes:

[0025] The vibration sensor detects the real-time vibration signal of the fan blades and feeds the real-time vibration signal back to the control device, so that the control device adjusts the control signal based on the real-time vibration signal.

[0026] In a preferred embodiment of the present invention, the process by which the driving circuit drives the at least one actuator to vibrate according to the control signal is as follows:

[0027] The drive circuit converts the control signal into a corresponding digital signal, then converts the digital signal into a corresponding analog signal, and then amplifies the analog signal before sending it to the at least one actuator to drive the at least one actuator to vibrate.

[0028] In a preferred embodiment of the present invention, the method further includes:

[0029] The fan blades are rotated inside the vacuum chamber by the rotating test bench.

[0030] By adopting the above technical solution, the present invention has the following beneficial effects:

[0031] This invention, by incorporating a control device, drive circuit, and actuator, converts electrical energy into vibrational energy to excite fan blades, causing them to vibrate according to a preset mode shape, simulating high-cycle loads. This high-cycle load, combined with the low-cycle load from the fan blades' own rotation, successfully simulates the combined high- and low-cycle load excitation experienced by the fan blades during operation. Since the excitation load and the fan blade rotation speed are independent and unaffected by the blade speed, the high- and low-cycle loads acting simultaneously on the fan blades do not interfere with each other. This allows for flexible simulation of the excitation experienced by the blades under real-world operating conditions, effectively improving the accuracy and reliability of fan blade fatigue life prediction. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the vibration system for high- and low-cycle combined fatigue testing of fan blades provided in Embodiment 1 of the present invention.

[0033] Figure 2 This is a schematic flowchart of the vibration excitation method for high- and low-cycle combined fatigue testing of fan blades provided in Embodiment 2 of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0035] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0036] Example 1

[0037] This embodiment provides an architecture diagram of a vibration excitation system for high- and low-cycle combined fatigue testing of fan blades, as shown below. Figure 1 As shown, the system includes: a rotary test bench 3 disposed within a vacuum chamber 1 to drive fan blades 2 to rotate within the vacuum chamber 1; at least one actuator 4 (two are shown in the figure) mounted on the fan blades 2; a drive circuit 5 connected to the at least one actuator 4; and a control device 6 for controlling the drive circuit 5 to drive the at least one actuator 4 to vibrate. The control device 6 controls the output load of the at least one actuator 4 according to the target excitation waveform and the current / voltage amplitude.

[0038] In this embodiment, the actuator 4 is made of a piezoelectric material with high electromechanical coupling performance. Preferably, the piezoelectric material is an MFC (Macro-Fiber Composite) piezoelectric material. MFC piezoelectric material is a novel smart material that simultaneously considers performance and applicability. On the one hand, it has good flexibility, which can be applied to situations where the structure undergoes large deformation and / or large rotation angles, or adapt to complex structures with large curvature. On the other hand, it has a stronger actuation effect than piezoelectric polymers or even piezoelectric ceramics, and can apply a wider range of actuation voltages. When an MFC piezoelectric patch is used as the actuator 4, it has advantages such as high output frequency response, fast dynamic response, large load capacity, stable performance, no heat generation, no noise generation, and low susceptibility to external force interference. At the same time, it has better durability and flexibility than traditional piezoelectric materials.

[0039] In this embodiment, the drive circuit 5 includes a signal conversion module 51, an analog signal generator 52, a power amplifier 53, and a slip ring 7 connected in sequence. The signal conversion module 51 converts the control signal output by the control device 6 into a corresponding digital signal; the analog signal generator 52 converts the digital signal into a corresponding analog signal; and the power amplifier 53 amplifies the analog signal and sends it through the slip ring 7 to the at least one actuator 4 to drive the actuator 4 to vibrate, thereby exciting the fan blades 2 to vibrate.

[0040] Furthermore, to ensure consistent excitation load output by actuator 4 during high- and low-cycle combined fatigue testing, the system in this embodiment may further include: a vibration sensor 8 mounted on the fan blade 2, and a data acquisition device 9 connected between the vibration sensor 8 and the control device 6. The vibration sensor 8 is used to detect the real-time vibration signal of the fan blade 2; the data acquisition device 9 is used to acquire the real-time vibration signal detected by the vibration sensor 8 through a slip ring 7, and feed the real-time vibration signal back to the control device 6, so that the control device 6 controls the drive circuit 5 based on the real-time vibration signal.

[0041] Specifically, after receiving the real-time vibration signal of the fan blade 2, the control device 6 adjusts the input current / voltage to the actuator 4 according to the difference between the real-time vibration signal of the fan blade 2 and the target vibration signal, in accordance with a predetermined control algorithm, so as to ensure that the output load of the excitation system remains stable and to facilitate the simulation of the high-cycle load on the fan blade 2 when the engine is working.

[0042] Preferably, the vibration sensor 8 can be implemented using a laser vibrometer or a vibration sensor 8 based on an MFC patch. The number and position of the actuators 4 can be optimized according to the target excitation mode shape, such as through topology optimization design. Furthermore, the data acquisition device 9 is preferably implemented using a digital acquisition card, and the drive circuit 5 is preferably implemented using an output card, to realize programmable inductors and negative capacitors, avoiding the problem of unacceptably large additional mass caused by using coils to implement inductors.

[0043] This embodiment, by setting up a control device 6, a drive circuit 5, and an actuator 4, can convert electrical energy into vibrational energy to excite the fan blade 2, causing it to vibrate according to a preset mode shape, simulating high-cycle load. This high-cycle load, combined with the low-cycle load from the fan blade 2's own rotation, successfully simulates the combined high- and low-cycle load excitation experienced by the fan blade 2 during its working state. Simultaneously, since the excitation load and the rotational speed of the fan blade 2 are independent and unaffected by the blade's rotational speed, the high- and low-cycle loads applied by this invention do not interfere with each other when acting simultaneously on the fan blade 2. This allows for flexible simulation of the excitation experienced by the blade under real-world working conditions, thereby effectively improving the accuracy and reliability of fatigue life prediction for the fan blade 2.

[0044] Example 2

[0045] This embodiment provides a vibration excitation method for high- and low-cycle combined fatigue testing of fan blades, implemented based on the vibration system provided in Embodiment 1, such as... Figure 2 As shown, the method specifically includes the following steps:

[0046] S1, the fan blades 2 are driven to rotate at a predetermined speed in the vacuum chamber 1 by the rotating test bench 3.

[0047] S2, the control device 6 outputs a control signal to the drive circuit 5 so that the drive circuit 5 drives the at least one actuator 4 to vibrate according to the control signal.

[0048] Specifically, the control device 6 can be a control program developed based on LabVIEW or Simulink software, which can output corresponding control signals according to the target excitation waveform and current / voltage amplitude.

[0049] In this embodiment, the process by which the driving circuit 5 drives the at least one actuator 4 to vibrate according to the control signal is as follows:

[0050] First, the control signal is converted into a corresponding digital signal by the signal conversion module 51 in the drive circuit 5; then, the digital signal is converted into a corresponding analog signal by the analog signal generator 52 in the drive circuit 5; finally, the analog signal is amplified by the power amplifier 53 in the drive circuit 5 and sent to the at least one actuator 4 through the slip ring 7 to drive the at least one actuator 4 to vibrate, thereby exciting the fan blades 2 to vibrate.

[0051] Preferably, the method of this embodiment further includes: detecting the real-time vibration signal of the fan blade 2 by the vibration sensor 8, so that the control device 6 adjusts the control signal based on the real-time vibration signal, thereby ensuring that the output load of the excitation system remains stable and facilitating the simulation of the high-cycle load on the fan blade 2 when the engine is working.

[0052] In this embodiment, the operation of the control device 6, drive circuit 5, and actuator 4 converts electrical energy into vibrational energy to excite the fan blade 2, causing it to vibrate according to a preset mode shape, simulating high-cycle load. This high-cycle load, combined with the low-cycle load of the fan blade 2's own rotation, successfully simulates the combined high- and low-cycle load excitation experienced by the fan blade 2 during its working state. Since the excitation load and the rotational speed of the fan blade 2 are independent of each other and are not affected by the blade's rotational speed, the high- and low-cycle loads applied by this invention do not interfere with each other when acting simultaneously on the fan blade 2. This allows for flexible simulation of the excitation experienced by the blade under real working conditions, thereby effectively improving the accuracy and reliability of fatigue life prediction for the fan blade 2.

[0053] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A vibration excitation system for high- and low-cycle combined fatigue testing of fan blades, characterized in that, include: A rotating test bench installed inside the vacuum chamber is used to drive the fan blades to rotate inside the vacuum chamber. At least one actuator is mounted on the fan blade; A drive circuit is connected to the at least one actuator; as well as A control device for controlling the drive circuit to drive the at least one actuator to vibrate; The vibration sensor installed on the fan blade is used to detect the real-time vibration signal of the fan blade and feed the real-time vibration signal back to the control device, so that the control device controls the drive circuit based on the real-time vibration signal; The vibration sensor and the actuator are mounted on the same side of the fan blades; The control device is used to adjust the input current / voltage to the actuator according to a predetermined control algorithm based on the difference between the real-time vibration signal of the fan blade and the target vibration signal after receiving the real-time vibration signal of the fan blade, so as to ensure that the output load of the excitation system is continuously stable and simulates high-cycle load; the high-cycle load and the low-cycle load of the fan blade rotation work together to simulate the high- and low-cycle composite load excitation of the fan blade in the working state. A data acquisition device is provided, which is used to acquire the real-time vibration signal detected by the vibration sensor through a slip ring, and to feed the real-time vibration signal back to the control device so that the control device controls the drive circuit based on the real-time vibration signal.

2. The fan blade high- and low-cycle combined fatigue test excitation system according to claim 1, characterized in that, The driving circuit includes: A signal conversion module is used to convert the control signals output by the control device into corresponding digital signals; An analog signal generator is used to convert the digital signal into a corresponding analog signal; A power amplifier is used to amplify the analog signal and send it to the at least one actuator.

3. The vibration system for high- and low-cycle combined fatigue testing of fan blades according to claim 1, characterized in that, The drive circuit is connected to the at least one actuator via a slip ring.

4. The fan blade high- and low-cycle combined fatigue test excitation system according to claim 1, characterized in that, The actuator is made of piezoelectric material.

5. A vibration excitation method for high- and low-cycle combined fatigue testing of fan blades, implemented based on the vibration excitation system for high- and low-cycle combined fatigue testing of fan blades according to any one of claims 1-4; characterized in that, The method includes: The control device outputs a control signal to the drive circuit, so that the drive circuit drives the at least one actuator to vibrate according to the control signal. The vibration sensor detects the real-time vibration signal of the fan blades and feeds the real-time vibration signal back to the control device, so that the control device adjusts the control signal based on the real-time vibration signal.

6. The vibration excitation method for high- and low-cycle combined fatigue testing of fan blades according to claim 5, characterized in that, The process by which the drive circuit drives the at least one actuator to vibrate according to the control signal is as follows: The drive circuit converts the control signal into a corresponding digital signal, then converts the digital signal into a corresponding analog signal, and then amplifies the analog signal before sending it to the at least one actuator to drive the at least one actuator to vibrate.

7. The vibration excitation method for high- and low-cycle combined fatigue testing of fan blades according to claim 5, characterized in that, The method further includes: The fan blades are rotated inside the vacuum chamber by the rotating test bench.

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