A vibration experimental device for simulating a breathing crack blade
By designing a vibration experimental device to simulate breathing crack blades and using split blades to simulate breathing crack parameters, low-cost and high-precision breathing crack fault diagnosis was achieved, solving the problem of experimental reproduction in existing technologies and verifying the dynamic characteristics of breathing crack blades.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- NAT UNIV OF DEFENSE TECH
- Filing Date
- 2025-07-29
- Publication Date
- 2026-05-26
AI Technical Summary
Existing technologies lack suitable experimental methods to reproduce and verify the vibration response signals of breathing crack blades. Real crack blades are rare and difficult to obtain. The preparation of fatigue cracks is costly and the parameters are difficult to match. Cracks prepared by wire cutting are inconsistent with the actual failure modes.
A vibration experimental device for simulating a breathing crack blade is designed. A split blade is used to simulate the cracked blade. The vibration response of the blade is measured by a vibration excitation generator and a signal acquisition device. The parameters of the breathing crack are precisely controllable by using a split blade, which includes a combination of the blade body and the docking unit, to simulate the shape and location of the breathing crack.
The vibration response characteristics of breathing crack blades were reproduced at low cost and with high precision. The experimental results were in good agreement with the theoretical analysis, filling the gap in experimental reproduction in the research on breathing crack fault diagnosis.
Smart Images
Figure CN224286318U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of blade dynamics experiments, and in particular to a vibration experimental device for simulating breathing cracks in blades, which is mainly used for the study of vibration characteristics of cracked blades. Background Technology
[0002] Blades are critical components in heavy equipment such as aero engines and gas turbines. During equipment operation, due to the high-speed rotation of the rotor and complex airflow conditions, blades are highly susceptible to fatigue damage, leading to irreversible failures such as cracks. To promptly detect blade cracks, studying the characteristics of the vibration response signals of cracked blades and achieving cracked blade signal identification has always been an important research topic for scholars in the field of fault diagnosis.
[0003] Current research on blade vibration characteristics, based on fracture mechanics theory, typically assumes that the initiating crack is a breathing crack model. However, current research on the vibration response signals of breathing cracked blades lacks suitable experimental methods for reproduction and verification. There are currently three experimental verification methods: first, selecting real blades with cracked failures; second, accelerating the failure of blades through mechanical loading, chemical corrosion, or thermal corrosion to create breathing cracks; and third, creating cracks on intact blades through wire cutting. However, real cracked blades are rare and difficult to obtain; accelerated failure methods for creating fatigue cracks are costly, and the crack parameters are difficult to match with those set in theoretical studies; cracks created by wire cutting are actually open-end cracks, which do not match the vibration response characteristics of breathing crack failure modes caused by fatigue in actual equipment operation. Therefore, it is necessary to study a vibration experimental device that simulates cracked blades with dynamic characteristics consistent with those of real cracked blades, to achieve research on the dynamic characteristics of cracked blades at a lower cost. Utility Model Content
[0004] To address the problems existing in the prior art, this utility model provides a vibration experimental device for simulating a breathing crack blade. It uses a split blade to simulate a cracked blade to study the vibration response characteristics of a blade with a breathing crack. It features low design cost and precise controllability of various parameters of the breathing crack.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] A vibration experimental device for simulating a breathing crack blade, the vibration experimental device comprising a bladed disk, a vibration excitation generator, and a vibration signal acquisition device;
[0007] The bladed disk has at least one blade; at least one blade is a simulated breathing crack blade; the simulated breathing crack blade includes a blade body and a docking unit; the blade body has a notch, and the docking unit corresponds to the shape and size of the notch; the docking unit is installed at the notch, and the combination of the docking unit and the blade body is consistent with the shape and size of the blade, and the side end face of the docking unit opposite to the blade body is not connected, for simulating the breathing crack of the blade;
[0008] The vibration excitation generator is used to excite the loaded blade, causing the blade to vibrate;
[0009] The vibration signal acquisition device is used to measure the displacement vibration response of the blade.
[0010] Furthermore, the notch is the portion of the blade that has been cut away according to breathing crack parameters; the breathing crack parameters include crack length, crack depth, and crack location.
[0011] Furthermore, the side end face of the notch on the blade body is set as a first mating surface, the surface of the notch is set as a first contact surface, and the docking unit has a second mating surface that matches the first mating surface and a second contact surface that matches the first contact surface;
[0012] The length and width of the first and second mating surfaces are respectively the crack length and the crack depth, and the positions of the first and second mating surfaces in the blade are the crack locations;
[0013] When the docking unit is placed at the notch, the first contact surface and the second contact surface are in contact, while the first mating surface and the second mating surface are not connected, simulating the breathing crack of the blade.
[0014] Furthermore, adhesive is applied to the first contact surface and the second contact surface respectively to bond and fix the blade body to the docking unit.
[0015] Furthermore, the adhesive is a structural metal bonding adhesive.
[0016] Furthermore, the distance between the vibration excitation generator and the blade satisfies the effective range of the vibration excitation generator, and the force output surface of the vibration excitation generator is parallel to the side surface of the blade; the acquisition end of the vibration signal acquisition device is perpendicular to the side surface of the blade excited by the vibration excitation generator, and is directly opposite the point to be measured on the side surface of the blade.
[0017] Furthermore, the vibration excitation generator is a non-contact exciter, and the vibration signal acquisition device is a laser displacement sensor.
[0018] Furthermore, the vibration experimental apparatus also includes a signal generator and a computer; the signal generator is used to generate an excitation loading signal for the vibration experimental target; the signal generator is connected to the vibration excitation generator and the computer respectively; the computer summarizes and records the excitation loading signal, and the vibration excitation generator excites the blade according to the excitation loading signal;
[0019] The vibration signal acquisition device is connected to the computer, and the computer summarizes, records, and analyzes the displacement signals acquired by the vibration signal acquisition device.
[0020] Furthermore, the bladed disk also includes a disc, and the blades are fitted onto the disc via a ring.
[0021] Furthermore, the vibration experimental device also includes an experimental platform and a clamp, with the bladed disk mounted on the experimental platform via the clamp; the vibration excitation generator and the vibration signal acquisition device are respectively arranged on the outside of the experimental platform.
[0022] The beneficial effects of this utility model are:
[0023] This invention presents a vibration experimental device for simulating breathing crack blades. The device employs a split-type blade design to simulate breathing cracks, offering advantages such as low design cost and precise control over various parameters of the breathing crack. It solves the problem of difficulty in experimentally reproducing breathing crack faults in blade dynamics theory research, achieving accurate reproduction of breathing crack faults and ensuring the simulated crack matches the conditions set in theoretical analysis and numerical simulation. The results of dynamic experiments conducted using this device can also reproduce the relevant dynamic response characteristics of breathing crack blades studied in theory. This invention demonstrates high feasibility in reproducing the vibration response of breathing cracks, filling the gap in research on breathing crack blade fault diagnosis that lacks a low-cost, high-precision experimental reproduction method. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the vibration experimental device for simulating a breathing crack blade according to this utility model.
[0025] Figure 2 This is a schematic diagram of the bladed disk containing simulated breathing crack blades in this utility model;
[0026] Figure 3 The theoretical displacement response diagram of the blade tip of the breathing crack obtained from finite element theory analysis;
[0027] Figure 4 The blade tip displacement response diagram obtained for verification of this utility model;
[0028] Figure 5The spectrum of the theoretical displacement response at the tip of the breathing crack blade obtained by finite element analysis.
[0029] Figure 6 The image shows the blade tip displacement response spectrum obtained for verification of this utility model.
[0030] Among them: 1-Experimental platform, 2-Clamping fixture, 3-Disc, 4-Blade, 4.1-Blade body, 4.1.1-First mating surface, 4.1.2-First contact surface, 4.2-Dating unit, 4.2.1-Second mating surface, 4.2.2-Second contact surface, 5-Vibration excitation generator, 6-Vibration signal acquisition device, 7-Signal generator, 8-Computer. Detailed Implementation
[0031] To enable those skilled in the art to better understand the technical solutions of this application, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0032] The directional terms such as above, below, left, right, front, and back used in this application are based on the positional relationships shown in the attached drawings. Different attached drawings may result in different positional relationships, therefore they should not be interpreted as limitations on the scope of protection.
[0033] In this utility model, the terms "installation," "connection," "interlocking," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a connection that allows communication, a direct connection, or an indirect connection through an intermediate medium. They can also refer to the internal connection of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.
[0034] This embodiment describes a vibration experimental device for simulating a breathing crack blade, such as... Figure 1 As shown, the vibration experimental device includes an experimental platform 1, a clamp 2, a disk 3, a blade 4, a vibration excitation generator 5, a vibration signal acquisition device 6, a signal generator 7, and a computer 8.
[0035] The disk 3 is mounted on the experimental table 1 by the clamp 2. One or more blades 4 are evenly distributed on the circumference of the disk 3. The disk 3 and the blades 4 form a bladed disk. Multiple blades 4 can be directly mounted on the circumference of the disk 3, or they can be evenly mounted on a ring to form a blade group, which is then fitted onto the disk 3 by the ring.
[0036] In this embodiment, the experimental platform 1 is provided with multiple connection holes for installing the clamp 2. The clamp 2 can be installed by selecting the appropriate connection hole according to the specifications of the impeller.
[0037] In this embodiment, at least one of the multiple blades 4 is a simulated breathing crack blade, which is the blade to be studied in the experiment. The simulated breathing crack blade is a split blade structure used to simulate a blade with an internal crack failure surface.
[0038] like Figure 2 The simulated breathing crack blade shown includes a blade body 4.1 and a docking unit 4.2. The blade body 4.1 is the remaining portion after cutting and removing parts according to the breathing crack parameters. After cutting, a notch is formed on the blade body 4.1, and the surface where the notch is located forms a stepped surface. The docking unit 4.2 corresponds to the shape and size of the notch. After being fitted and shaped at the notch of the blade body 4.1, the docking unit 4.2 and the assembly of the blade body 4.1 have the same shape and size as other blades 4 without notches. This embodiment uses the notch on the front surface of the blade body 4.1 as an example for illustration. Specifically:
[0039] The side end face of the notch on the blade body 4.1 is designated as the first mating surface 4.1.1, and the surface of the notch is designated as the first contact surface 4.1.2. The docking unit 4.2 has a second mating surface 4.2.1 that matches the first mating surface 4.1.1 and a second contact surface 4.2.2 that matches the first contact surface 4.1.2. When the docking unit 4.2 is placed at the notch of the blade body 4.1, the first contact surface 4.1.2 and the second contact surface 4.2.2 mate, while the first mating surface 4.1.1 and the second mating surface 4.2.1 are opposite but not connected, simulating the breathing crack of the blade. After the blade body 4.1 and the docking unit 4.2 are tightly fitted together, the surface of the blade 4 is cleaned to ensure that the surface of the blade 4 is free of contamination, thus avoiding the influence of contaminants on the experimental results. Preferably, an adhesive (such as structural metal bonding adhesive) can be applied thinly and evenly to the first contact surface 4.1.2 and the second contact surface 4.2.2 respectively to achieve the bonding and fixation of the blade body 4.1 and the docking unit 4.2; the blade surface is cleaned by wiping with anhydrous ethanol.
[0040] According to Wu Zhiyuan's paper "Axial-bending coupling vibration characteristics of a rotating blade with breathing crack" from Shanghai Jiao Tong University, the internal crack surface that causes damage in the blade can be uniquely determined by breathing parameters such as crack length, crack depth, and crack location in a breathing crack that has undergone crack simulation and dynamic characteristic experiments.
[0041] In this embodiment, the location and dimensions of the first mating surface 4.1.1 and the second mating surface 4.2.1 correspond to the location and dimensions of the crack fracture surface. Specifically, the internal crack surface ≌ the mating surface, the length of the mating surface equals the crack length, and the width of the mating surface equals the crack depth. The position of the mating surface within the blade 4 is the same as the position of the internal crack failure surface. Furthermore, the dimensional tolerance of the blade body 4.1 and the docking unit 4.2 does not exceed ±0.1 mm. The first contact surface 4.1.2 and the second contact surface 4.2.2 undergo surface treatment to ensure that their surface roughness Ra is no greater than 3.2 μm. This embodiment thus sets the dimensions and shape of the blade body 4.1 and the docking unit 4.2 to simulate the internal crack failure surface of the blade, thereby reproducing the breathing crack blade.
[0042] A vibration excitation generator 5 is used to excite the loaded blade 4, causing the blade tip of the blade 4 to vibrate. It is set on the outside of the experimental platform 1, and the distance between it and the blade 4 meets the effective range of the vibration excitation generator 5. The force output surface of the vibration excitation generator 5 is parallel to the side of the blade 4. The signal generator 7 is connected to the vibration excitation generator 5 and the computer 8 respectively. The signal generator 7 generates the excitation loading signal of the vibration experimental target. The vibration excitation generator 5 excites the blade 4 according to the excitation loading signal, causing the blade tip of the blade 4 to vibrate. The computer 8 summarizes and records the excitation loading signal.
[0043] The vibration signal acquisition device 6 is used to measure the displacement vibration response of the blade 4. It is arranged on the outside of the experimental platform 1, and its acquisition end is perpendicular to the side of the blade 4 excited by the vibration excitation generator 5, facing the point to be measured on the side of the blade 4. The vibration signal acquisition device 6 is connected to the computer 8. After the displacement signal acquired by the vibration signal acquisition device 6 is transmitted to the computer 8, the computer 8 summarizes, records and analyzes the data.
[0044] Preferably, the vibration excitation generator 5 is a non-contact exciter, and the vibration signal acquisition device 6 is a laser displacement sensor. The light source emitted by the sensor is perpendicular to the side of the blade 4 excited by the vibration excitation generator 5, so that the light spot is directly facing the test point on the side of the blade 4. During the experiment, neither the vibration excitation generator 5 nor the vibration signal acquisition device 6 comes into contact with the blade 4, thus avoiding changes to the true dynamic characteristics of the blade 4.
[0045] The vibration test apparatus of this embodiment is used to test the vibration response of a simulated breathing crack blade, and to verify the experimental reproduction effect of the dynamic characteristics of the breathing crack in the theoretical study.
[0046] Signal generator 7 sends a target frequency sweep excitation loading signal to vibration excitation generator 5. The frequency sweep range covers the first natural frequency of blade 4. In this embodiment, the experiment is conducted with the first natural frequency ranging from 10Hz to 400Hz.
[0047] The clamp 2 maintains the clamping state of the disk 3, and the signal generator 7 sends a fixed frequency excitation loading signal to the vibration excitation generator 5. In this embodiment, the fixed frequency is 80Hz as an example for the experiment.
[0048] During the process of frequency sweeping and fixed-frequency excitation of the vibration excitation generator 5 to simulate the breathing crack blade, the vibration signal acquisition device 6 measures the vibration displacement response of the test point on the blade 4 in real time, and transmits the vibration displacement data to the computer 8 for aggregation, analysis and processing.
[0049] The characteristics and errors of the experimentally measured signal and the theoretically calculated vibration response signal containing the breathing crack were compared under the same loading method.
[0050] Blade 4 was excited using a frequency sweep excitation method. Figure 3 The theoretical displacement response of the blade tip with a breathing crack, obtained from finite element analysis, is shown. Figure 4 The blade tip displacement response obtained by experimental verification using the vibration experimental setup of this embodiment under the same conditions is shown.
[0051] Blade 4 is excited using a fixed-frequency excitation method. Figure 5 The spectrum of the theoretical displacement response of the blade tip with a breathing crack, obtained by analysis using finite element theory, is shown. Figure 6 The blade tip displacement response spectrum obtained by experimental verification using the vibration experimental apparatus of this embodiment under the same conditions is shown.
[0052] The above comparison shows that the vibration experimental device proposed in this embodiment not only presents the dynamic characteristics of the breathing crack in the theoretical study, but also the experimental test results are in high agreement with the finite element theory analysis results, proving the feasibility of the invention.
[0053] Although the principles of this utility model have been described in detail above with reference to preferred embodiments, those skilled in the art should understand that the above embodiments are merely illustrative explanations of the implementation of this utility model and are not intended to limit the scope of this utility model. The details in the embodiments do not constitute a limitation on the scope of this utility model. Any obvious changes, such as equivalent transformations or simple substitutions, based on the technical solution of this utility model without departing from its spirit and scope fall within the protection scope of this utility model.
Claims
1. A vibration testing apparatus for simulating a breathing crack blade, characterized by, The vibration experimental device includes a bladed disk, a vibration excitation generator (5), and a vibration signal acquisition device (6); The bladed disk has at least one blade (4); at least one blade (4) is a simulated breathing crack blade; the simulated breathing crack blade includes a blade body (4.1) and a docking unit (4.2); the blade body (4.1) has a notch, and the docking unit (4.2) corresponds to the shape and size of the notch; the docking unit (4.2) is installed at the notch, and the combination of the docking unit (4.2) and the blade body (4.1) is consistent with the shape and size of the blade (4), and the side end faces of the docking unit (4.2) and the blade body (4.1) are not connected, for simulating the breathing crack of the blade; The vibration excitation generator (5) is used to excite the loaded blade (4) to cause the blade (4) to vibrate; The vibration signal acquisition device (6) is used to measure the displacement vibration response of the blade (4).
2. The vibration experimental apparatus simulating a breathing crack blade according to claim 1, wherein The notch is the portion of the blade (4) that has been cut away according to the breathing crack parameters; the breathing crack parameters include crack length, crack depth and crack location.
3. The vibration experimental apparatus for simulating a breathing cracked blade according to claim 2, characterized in that, The side end face of the notch on the blade body (4.1) is designated as the first mating surface. 4.1.1), the surface of the notch is designated as a first contact surface (4.1.2), and the docking unit (4.2) has a second contact surface (4.2.1) that matches the first contact surface (4.1.1) and a second contact surface (4.2.2) that matches the first contact surface (4.1.2); The length and width of the first mating surface (4.1.1) and the second mating surface (4.2.1) are respectively the crack length and the crack depth, and the positions of the first mating surface (4.1.1) and the second mating surface (4.2.1) in the blade (4) are the crack positions; When the docking unit (4.2) is placed at the notch, the first contact surface (4.1.2) and the second contact surface (4.2.2) dock together, while the first mating surface (4.1.1) and the second mating surface (4.2.1) are not connected, simulating the breathing crack of the blade.
4. The vibration experimental apparatus for simulating a breathing cracked blade according to claim 3, characterized in that, Adhesive is applied to the first contact surface (4.1.2) and the second contact surface (4.2.2) respectively to bond and fix the blade body (4.1) to the docking unit (4.2).
5. The vibration experimental apparatus for simulating a breathing cracked blade according to claim 4, characterized in that, The adhesive is a structural metal bonding adhesive.
6. The vibration experimental apparatus for simulating a breathing cracked blade according to claim 1, characterized in that, The distance between the vibration excitation generator (5) and the blade (4) satisfies the effective range of the vibration excitation generator (5), and the force output surface of the vibration excitation generator (5) is parallel to the side surface of the blade (4); the acquisition end of the vibration signal acquisition device (6) is perpendicular to the side surface of the blade (4) excited by the vibration excitation generator (5), and is directly opposite the test point on the side surface of the blade (4).
7. The vibration experimental apparatus for simulating a breathing cracked blade according to claim 1, characterized in that, The vibration excitation generator (5) is a non-contact exciter, and the vibration signal acquisition device (6) is a laser displacement sensor.
8. The vibration experimental apparatus for simulating a breathing cracked blade according to claim 1, characterized in that, The vibration test apparatus also includes a signal generator (7) and a computer (8); the signal generator (7) is used to generate an excitation loading signal for the vibration test target; the signal generator (7) is connected to the vibration excitation generator (5) and the computer (8) respectively; the computer (8) summarizes and records the excitation loading signal, and the vibration excitation generator (5) excites the blade (4) according to the excitation loading signal; The vibration signal acquisition device (6) is connected to the computer (8) for data exchange. The computer (8) summarizes, records and analyzes the displacement signals acquired by the vibration signal acquisition device (6).
9. The vibration experimental apparatus for simulating a breathing cracked blade according to claim 1, characterized in that, The bladed disk also includes a disc (3), and the blades (4) are fitted onto the disc (3) by means of a ring.
10. The vibration experimental apparatus for simulating a breathing crack blade according to claim 1, characterized in that, The vibration experimental device also includes an experimental platform (1) and a clamp (2). The bladed disk is mounted on the experimental platform (1) via the clamp (2). The vibration excitation generator (5) and the vibration signal acquisition device (6) are respectively arranged outside the experimental platform (1).