Composite material fan blade defect detection device and method

Abstract

The invention relates to a composite fan blade defect detection device and method, and the device comprises an ultrasonic generator which is used for generating a low-frequency ultrasonic wave with a set defect detection frequency, and the low-frequency ultrasonic wave is emitted to the surface of a to-be-detected composite fan blade region; the at least one group of transmitting probes and receiving probes are tightly attached to the surface of a to-be-detected composite material fan blade area during detection; the ultrasonic probe is used for transmitting low-frequency ultrasonic waves with set defect detection frequency to the surface of the to-be-detected composite fan blade through the transmitting probe and receiving reflected waves, returned by the to-be-detected composite fan blade, of the low-frequency ultrasonic waves through the receiving probe; the reflected wave processing module is connected with the receiving probe and is used for digitally processing the reflected wave acquired by the receiving probe; and the display is used for displaying the digitally processed emission wave and carrying out defect detection according to the amplitude change condition of the reflection wave. Compared with the prior art, the method has the advantages of convenient operation, high accuracy and the like.

Description

Technical Field

[0001] The present invention relates to the field of fan blade defect detection, and in particular to a fan blade defect detection device and method. Background Art

[0002] Composite wind turbine blades are sandwich structures consisting of an outer layer of glass fiber reinforced material, a middle core material, and another layer of glass fiber reinforced material. They have been widely used in wind turbine power generation due to their high strength and high stiffness. Wind turbine blades are key components of wind turbines, and their working conditions directly affect power generation efficiency and operational safety. Therefore, defect detection of composite wind turbine blades before delivery and installation is crucial.

[0003] At present, the defect detection of composite fan blades mainly adopts knocking detection and visual detection schemes, which have problems such as low sensitivity and low quantitative accuracy. The conventional ultrasonic blade defect detection scheme is aimed at ordinary fan blades. For composite fan blades, most of the energy of the ultrasonic wave will be absorbed by the middle core material in the sandwich structure, so the structural defects cannot be effectively identified.

[0004] Therefore, there is an urgent need to design a more accurate and efficient defect detection solution for composite wind turbine blades. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a fan blade defect detection device and method. By detecting the frequency and energy changes formed by low-frequency ultrasonic waves at the skin-core material interface, defect detection of composite material fan blades can be achieved more accurately and efficiently.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A composite material fan blade defect detection device, comprising:

[0008] An ultrasonic generator, used to generate low-frequency ultrasonic waves of a set defect detection frequency to be emitted to the surface of a composite material fan blade area to be detected;

[0009] At least one set of transmitting probes and receiving probes, which are arranged close to the surface of the composite material fan blade area to be tested during testing, and are used to transmit low-frequency ultrasonic waves of a set defect detection frequency to the surface of the composite material fan blade to be tested through the transmitting probe and receive the reflected waves of the low-frequency ultrasonic waves returned by the composite material fan blade to be tested through the receiving probe;

[0010] A reflected wave processing module, connected to the receiving probe, for digitally processing the reflected wave obtained by the receiving probe;

[0011] The display is used to display the digitally processed transmitted wave and perform defect detection based on the change in the amplitude of the reflected wave.

[0012] Preferably, the defect detection frequency of the low-frequency ultrasonic wave is set as follows: placing the transmitting probe on a non-destructive test block with the same structure as the composite fan blade to be tested, adjusting the RF gain, and selecting the frequency when the reflected wave is the highest as the defect detection frequency of the composite fan blade to be tested.

[0013] Preferably, the transmitting probe and the receiving probe are fixed on the bottom side of the ultrasonic generator, and the interval between the transmitting probe and the receiving probe is less than a set distance.

[0014] Preferably, the device comprises two sets of redundantly arranged transmitting probes and receiving probes.

[0015] Preferably, the reflected wave processing module comprises a preamplifier, a filter, a phase rotator and an A / D converter which are arranged in sequence.

[0016] According to a second aspect of the present invention, a method for using the composite material wind turbine blade defect detection device is provided, the method comprising:

[0017] Place the transmitting probe on a non-destructive test block with the same structure as the composite fan blade to be tested, adjust the RF gain, and select the frequency when the reflected wave is the highest as the defect detection frequency of the composite fan blade to be tested;

[0018] After determining the defect detection frequency, defect detection is carried out on the wind turbine blade area to be inspected. When the amplitude of the reflected wave displayed on the display rises sharply, it is determined that stratification or debonding exists at the monitoring point in the current wind turbine blade area. The boundary of stratification or debonding is determined by pushing the probe on the surface of the composite material wind turbine blade area to be inspected.

[0019] Preferably, the waveform at the time of the highest reflected wave on a test block with the same structure as the composite material fan blade to be tested and which is damageless is set as the reference horizontal line. After setting the reference horizontal line, it also includes: selecting at least 2 more test points on the test block for sensitivity verification. When the absolute value ratio of the amplitude error is lower than the set threshold, it is determined that the sensitivity verification has passed. After passing the sensitivity verification, defect detection is performed in the fan blade area to be tested.

[0020] Preferably, when the amplitude error absolute value ratio is lower than 10%, it is considered that the sensitivity verification has been passed, otherwise the defect detection frequency is re-determined.

[0021] Preferably, after determining the defect detection frequency, defect detection is performed on the composite material fan blade area to be inspected. When the amplitude of the reflected wave displayed on the display rises sharply, it is determined that stratification or debonding exists at the monitoring point in the current fan blade area, and the boundary of the stratification or debonding is determined by pushing the probe on the surface of the composite material fan blade area to be inspected.

[0022] Preferably, the single push displacement interval is determined according to the surface condition of the composite material fan blade area to be inspected, and defect detection is performed on each interval point using a one-transmit-one-receive method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Since most of the energy of the emitted ultrasonic wave will be absorbed by the middle core material in the sandwich structure of the composite fan blade, it is impossible to effectively identify structural defects. The present invention creatively provides a solution for defect detection of composite fan blades using low-frequency ultrasonic waves, which is more accurate and reliable and can detect 10x10mm debonding and delamination defects. Operators can directly perform defect detection on site through a one-transmit-one-receive method, which is more convenient to operate and further improves the efficiency of on-site detection.

[0025] (2) The present invention solves the problem of the knocking test being dependent on the tester's experience and hearing ability. The detection effectiveness can cover the knocking test and can detect debonding and delamination defects that it fails to find. The defect detection results are more objective and accurate, and the knocking test can be prevented from causing damage or secondary damage to the detection area.

[0026] (3) By placing the transmitting probe on a non-destructive test block with the same structure as the composite fan blade to be tested, adjusting the RF gain, and selecting the frequency when the reflected wave is the highest as the defect detection frequency of the composite fan blade to be tested, the defect detection frequency of each model of composite fan blade can be adjusted adaptively, which is more flexible and accurate.

[0027] (4) After obtaining the defect detection frequency, other test points are selected on the test block for sensitivity verification. After the sensitivity verification is passed, blade inspection is performed to avoid the inaccurate acquisition of a single defect detection frequency affecting the overall detection accuracy, and the reliability is higher.

[0028] (5) The transmitting probe and receiving probe groups are set redundantly. When a problem occurs in one group, the other group of probes can be directly enabled for detection to avoid the progress of on-site defect detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of a fan blade defect detection device in an embodiment;

[0030] Figure 2It is a schematic diagram of the operation of the fan blade defect detection device in the embodiment. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0032] Example

[0033] For composite fan blades, since most of the energy of the emitted ultrasonic waves will be absorbed by the middle core material in the sandwich structure, structural defects cannot be effectively identified. The present invention uses low-frequency ultrasonic waves for the first time to perform defect detection on composite fan blades. By detecting the frequency and energy changes formed by low-frequency ultrasonic waves at the skin-core material interface, defect detection on composite fan blades can be achieved more accurately and efficiently.

[0034] This embodiment provides a composite material fan blade defect detection device, which creatively uses low-frequency ultrasonic waves for defect detection. Figure 1 and Figure 2 As shown, the device comprises:

[0035] An ultrasonic generator, used to generate low-frequency ultrasonic waves of a set defect detection frequency to be emitted to the surface of a composite material fan blade area to be detected;

[0036] At least one set of transmitting probes and receiving probes, which are arranged close to the surface of the composite material fan blade area to be tested during testing, and are used to transmit low-frequency ultrasonic waves of a set defect detection frequency to the surface of the fan blade to be tested through the transmitting probe and receive the reflected waves of the low-frequency ultrasonic waves returned by the composite material fan blade to be tested through the receiving probe;

[0037] A reflected wave processing module, connected to the receiving probe, for digitally processing the reflected wave obtained by the receiving probe;

[0038] The display is used to display the digitally processed transmitted wave and perform defect detection based on the change in the amplitude of the reflected wave.

[0039] In this embodiment, the defect detection frequency of the low-frequency ultrasonic wave is set as follows: the transmitting probe is placed on a non-destructive test block with the same structure as the composite fan blade to be tested, the RF gain is adjusted, and the frequency when the reflected wave is the highest is selected as the defect detection frequency of the composite fan blade to be tested.

[0040] Specifically, the reflected wave processing module of this embodiment includes a preamplifier, a filter, a phase rotator and an A / D converter which are arranged in sequence.

[0041] After phase-sensitive detection, the reflected wave is amplified in the preamplifier. After filtering and phase conversion, the A / D converter converts the analog signal into a digital signal, and the defect is displayed on the display as an amplitude change. The operator evaluates the integrity of the blade of the inspected and verified material by the amplitude and phase change rules, and can directly perform defect diagnosis in real time on site, and determine the nature of the defect more accurately based on the defect location, shape, signal amplitude and phase change.

[0042] The transmitting probe and the receiving probe are fixed on the bottom side of the ultrasonic generator, and the interval between the transmitting probe and the receiving probe is less than the set distance. As another preferred embodiment, the device includes two sets of redundantly arranged transmitting probes and receiving probes.

[0043] Specifically, the frequency range of the low-frequency ultrasonic wave in this embodiment is: 2.0kHz-20kHz, which is based on the depth that can penetrate the detection requirement; the length is: 1000μs-15000μs, which is based on the depth range that covers the detection requirement.

[0044] As shown in Table 1 below, this embodiment provides initial values ​​for setting the RF frequency for different thicknesses, so that subsequent fine-tuning can more quickly determine the defect detection frequency.

[0045] Table 1 Correspondence between detection frequency and thickness

[0046]

[0047] This embodiment also provides a composite material fan blade defect detection method, using the composite material fan blade defect detection device mentioned above, the method comprises:

[0048] Place the transmitting probe on a non-destructive test block with the same structure as the composite fan blade to be tested, adjust the RF gain, and select the frequency when the reflected wave is the highest as the defect detection frequency of the composite fan blade to be tested;

[0049] After determining the defect detection frequency, defect detection is carried out on the wind turbine blade area to be inspected. When the amplitude of the reflected wave displayed on the display rises sharply, it is determined that stratification or debonding exists at the monitoring point in the current wind turbine blade area. The boundary of stratification or debonding is determined by pushing the probe on the surface of the composite material wind turbine blade area to be inspected.

[0050] In this embodiment, the waveform of the highest reflected wave on a test block with the same structure as the composite fan blade to be tested and without damage is set as the reference horizontal line. As another preferred embodiment, after setting the reference horizontal line, at least two test points are selected on the test block for sensitivity verification. When the absolute value ratio of the amplitude error is lower than the set threshold (set to 10% in this embodiment), it is determined that the sensitivity verification has passed. After passing the sensitivity verification, defect detection is performed in the fan blade area to be tested, otherwise the defect detection frequency is re-determined.

[0051] After determining the defect detection frequency, defect detection is carried out on the composite material fan blade area to be inspected. When the amplitude of the reflected wave displayed on the display rises sharply, it is determined that stratification or debonding exists at the monitoring point in the current fan blade area. The boundary of stratification or debonding is determined by pushing the probe on the surface of the composite material fan blade area to be inspected.

[0052] The single push displacement interval is determined according to the surface condition of the composite material fan blade area to be inspected, and defect detection is carried out on each interval point using a one-transmit-one-receive method.

[0053] After determining the defect detection frequency, defect detection is carried out on the wind turbine blade area to be inspected. When the amplitude of the reflected wave displayed on the display rises sharply, it is determined that stratification or debonding exists at the monitoring point in the current wind turbine blade area. The boundary of stratification or debonding is determined by pushing the probe on the surface of the composite material wind turbine blade area to be inspected.

[0054] The single push displacement interval is determined according to the surface condition of the composite material fan blade area to be inspected, and the defect detection is performed on each interval point using a one-shot-one-catch method. In the one-shot-one-catch mode, under the excitation of AC power of a specific frequency, the excitation signal is amplified after passing through the power amplifier to a level sufficient to excite the probe piezoelectric chip to oscillate, thereby exciting low-frequency ultrasonic waves. The low-frequency ultrasonic waves propagate in the material, encounter heterogeneous materials with different acoustic impedances, and are reflected back to the probe.

[0055] The composite material fan blade defect detection device of this embodiment can identify 220x160 mm 2 Skin-core delamination.

[0056] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A composite material fan blade defect detection device, characterized in that: include: An ultrasonic generator, used to generate low-frequency ultrasonic waves of a set defect detection frequency to be emitted to the surface of a composite material fan blade area to be detected; At least one set of transmitting probes and receiving probes, which are arranged close to the surface of the composite material fan blade area to be tested during testing, and are used to transmit low-frequency ultrasonic waves of a set defect detection frequency to the surface of the composite material fan blade to be tested through the transmitting probe and receive the reflected waves of the low-frequency ultrasonic waves returned by the composite material fan blade to be tested through the receiving probe; A reflected wave processing module, connected to the receiving probe, for digitally processing the reflected wave obtained by the receiving probe; The display is used to display the digitally processed transmitted wave and perform defect detection based on the change in the amplitude of the reflected wave.

2. A composite material fan blade defect detection device according to claim 1, characterized in that: The defect detection frequency of the low-frequency ultrasonic wave is set as follows: the transmitting probe is placed on a non-destructive test block with the same structure as the composite fan blade to be tested, the RF gain is adjusted, and the frequency when the reflected wave is the highest is selected as the defect detection frequency of the composite fan blade to be tested.

3. A composite material fan blade defect detection device according to claim 1, characterized in that: The transmitting probe and the receiving probe are fixed on the bottom side of the ultrasonic generator, and the interval between the transmitting probe and the receiving probe is less than the set distance.

4. The composite material fan blade defect detection device according to claim 1, characterized in that: The device comprises two groups of redundantly arranged transmitting probes and receiving probes.

5. The composite material fan blade defect detection device according to claim 1, characterized in that: The reflected wave processing module comprises a preamplifier, a filter, a phase rotator and an A / D converter which are arranged in sequence.

6. A method for using the composite material fan blade defect detection device according to claim 2, characterized in that: The method comprises: Place the transmitting probe on a non-destructive test block with the same structure as the composite fan blade to be tested, adjust the RF gain, and select the frequency when the reflected wave is the highest as the defect detection frequency of the composite fan blade to be tested; After determining the defect detection frequency, defect detection is carried out on the wind turbine blade area to be inspected. When the amplitude of the reflected wave displayed on the display rises sharply, it is determined that stratification or debonding exists at the monitoring point in the current wind turbine blade area. The boundary of stratification or debonding is determined by pushing the probe on the surface of the composite material wind turbine blade area to be inspected.

7. The method according to claim 6, characterized in that The waveform at the time of the highest reflected wave on a test block with the same structure as the composite wind turbine blade to be tested and without damage is set as the reference horizontal line. After setting the reference horizontal line, it also includes: selecting at least 2 test points on the test block for sensitivity verification. When the absolute value ratio of the amplitude error is lower than the set threshold, it is determined that the sensitivity verification has passed. After passing the sensitivity verification, defect detection is performed in the wind turbine blade area to be tested.

8. The method according to claim 7, characterized in that When the absolute value ratio of the amplitude error is lower than 10%, it is considered to have passed the sensitivity verification, otherwise the defect detection frequency is re-determined.

9. The method according to claim 6, characterized in that After determining the defect detection frequency, defect detection is carried out on the composite material fan blade area to be inspected. When the amplitude of the reflected wave displayed on the display rises sharply, it is determined that stratification or debonding exists at the monitoring point in the current fan blade area. The boundary of stratification or debonding is determined by pushing the probe on the surface of the composite material fan blade area to be inspected.

10. The method according to claim 6, characterized in that The single push displacement interval is determined according to the surface condition of the composite material fan blade area to be inspected, and defect detection is carried out on each interval point using a one-transmit-one-receive method.

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