Layered detection method for skin of wind power blade

Abstract

The invention discloses a wind power blade skin layering detection method, which adopts an ultrasonic detection probe of a bonding detector to detect the bonding quality of a blade skin, and analyzes the morphological difference of a received wave relative to a reference wave. An ultrasonic detection probe is pressed on glass fiber reinforced plastic on the outer side of the blade skin; when the waveform of the receiving wave is symmetrical and has stable amplitude, the bonding quality of the blade skin is good; when the amplitude of the received wave is increased and deviates along with the phase, the amplitude lifting amount of the amplitude of the received wave relative to the reference wave is larger than or equal to 30%, the phase offset amount of the received wave relative to the reference wave is larger than or equal to 15 degrees, and the waveform energy ratio lifting value of the received wave relative to the reference wave is larger than or equal to 20%, it is indicated that the blade skin has the layering defect; the waveform energy ratio is the ratio of low-frequency energy to high-frequency energy. Therefore, the blade skin layering defect can be detected in the detection process.

Description

Technical Field

[0001] The invention relates to a method for detecting delamination of a wind turbine blade skin, and belongs to the technical field of defect detection in a wind turbine blade production process. Background Art

[0002] Currently, there are two conventional methods for detecting delamination of wind turbine blade skin:

[0003] Method 1: After sanding the exterior paint, manual visual inspection is performed. This method has the following disadvantages: 1) It is a destructive test; once sanded, the original surface condition cannot be restored; 2) Each visual inspection is limited to the sanded area; 3) It consumes a lot of time and labor, affecting production efficiency; 4) The dust and waste generated by sanding may have an impact on the environment.

[0004] Method 2: Using a hammer to tap the wind turbine blade skin, followed by manual auditory inspection. This method has the following disadvantages: 1) It relies on the inspector's hearing and experience, which carries the risk of misjudgment or omission; 2) It can be difficult to detect small or minor delamination defects; 3) External noise can interfere with the inspector's auditory judgment, affecting inspection accuracy; and 4) This method relies primarily on qualitative auditory judgment and lacks quantitative data support. Summary of the Invention

[0005] The purpose of the present invention is to provide a wind turbine blade skin delamination detection method, which uses an adhesion detector to accurately detect the skin delamination defects of the wind turbine blade, and is suitable for detecting blade skin delamination defects during the wind turbine blade production process and when the wind farm is shut down.

[0006] In order to achieve the above technical objectives, the present invention will adopt the following technical solutions:

[0007] A method for detecting delamination of a wind turbine blade skin is disclosed. The method uses an ultrasonic detection probe of a bonding tester to detect the bonding quality of the blade skin. By analyzing the morphological differences between the received wave and the reference wave, the method identifies areas on the blade skin where delamination defects exist. The method specifically comprises the following steps:

[0008] Press the ultrasonic testing probe onto the fiberglass reinforced plastic outside the blade skin;

[0009] Push the ultrasonic detection probe forward continuously and when the push is stuck, push the ultrasonic detection probe forward in a jump;

[0010] When the received wave waveform is symmetrical and has a stable amplitude, it indicates that the bonding quality of the blade skin is good;

[0011] When the amplitude of the received wave increases and is accompanied by a phase shift, and the amplitude increase of the received wave relative to the reference wave is ≥30%, the phase shift of the received wave relative to the reference wave is ≥15°, and the waveform energy ratio increase of the received wave relative to the reference wave is ≥20%, it indicates that there is a delamination defect in the blade skin; the waveform energy ratio is the ratio of low-frequency energy to high-frequency energy.

[0012] Preferably, the reference wave is obtained by:

[0013] Select three or more sites with good bonding quality near the blade skin area to be inspected and record them as reference wave collection points;

[0014] Use ultrasonic detection probe to collect waveform data at each reference wave collection point;

[0015] The obtained waveform data is averaged to obtain the reference wave waveform, and the amplitude of the reference wave is ensured to be basically stable between the virtual horizontal grid lines.

[0016] Adjust the frequency and gain of the reference wave to make it symmetrical.

[0017] Preferably, the distance between each reference wave collection point is ≥50 mm.

[0018] Preferably, the error of the amplitude of the reference wave relative to the imaginary horizontal grid line is ±10%.

[0019] Preferably, when the ultrasonic detection probe is pressed against the fiberglass reinforced plastic on the outer side of the blade skin, the four support columns at the bottom of the ultrasonic detection probe should be completely pressed against the surface of the fiberglass reinforced plastic on the outer side of the blade skin.

[0020] Preferably, at the initial moment of testing the adhesion quality of the blade skin, the frequency needs to be adjusted by the instrument flywheel of the adhesion tester so that the waveform of the received wave is bilaterally symmetrical.

[0021] Preferably, at the initial moment of testing the bonding quality of the blade skin, it is necessary to select the RF gain item of the bonding tester to adjust the gain through the instrument flywheel so that the amplitude of the received wave is located between the virtual horizontal grid lines.

[0022] Preferably, when there is a delamination defect in the blade skin, the critical value of the amplitude of the received wave is 1.5 times the amplitude of the reference wave.

[0023] Preferably, during the inspection of the bonding quality of the blade skin, the side of the ultrasonic detection probe engraved with a white line is moved from the area with good bonding quality of the blade skin to the area to be inspected. When the amplitude of the received wave is on the solid line, it indicates that there is a delamination defect in the area to be inspected, and the side of the ultrasonic detection probe engraved with a white line is the boundary of the delamination defect in the area to be inspected.

[0024] Based on the above technical objectives, the present invention has the following advantages over the prior art:

[0025] The wind turbine blade skin delamination detection method of the present invention is implemented based on an adhesion detector. Therefore, it has the following overall characteristics:

[0026] ● Non-destructive testing: No need to polish the paint surface, no dust and waste will be generated, and no impact on the environment;

[0027] ●High detection efficiency: The benchmark model can be adjusted once for the same structural area and used continuously;

[0028] ●High data reliability: Directly displays amplitude changes, independent of the tester's experience, with low risk of misjudgment or missed judgment;

[0029] ●Higher detection accuracy: Compared with the knock detection method, it can detect smaller skin delamination defects;

[0030] ● Low reliance on personnel skills: The operation is simple and the test personnel can operate it after simple training;

[0031] ●The detection process is simple: no coupling agent is needed, just use the probe contacts to make contact, and it can be operated with one touch. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of delamination detection of the wind turbine blade skin delamination detection method according to the present invention;

[0033] Figure 2 Schematic diagram of the amplitude during delamination detection. In the figure, (a) shows the amplitude of a well-bonded area during delamination detection; (b) shows the amplitude of a delamination defect in the detection area during delamination detection.

[0034] In the figure: 1-transmitter-receiver probe; 2-fiberglass outer surface of blade skin; 3-delamination defect; 4-core material of blade skin; 5-probe signal transmitter; 6-probe signal receiver; 7-sound wave; 8-wave amplitude solid line boundary; 9-wave amplitude. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way serves as any limitation on the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention. Unless otherwise specified, the relative arrangement of components and steps, expressions and numerical values ​​described in these embodiments do not limit the scope of the present invention. Technologies, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the technologies, methods and equipment should be considered part of the specification. In all examples shown and discussed here, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values.

[0036] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations).

[0037] like Figure 1 、 Figure 2 As shown, the wind turbine blade skin delamination detection method of the present invention uses an adhesion tester to detect the adhesion quality of the blade skin, thereby confirming whether there is a delamination defect in the detection area by analyzing the morphological difference between the received wave and the reference wave. The method specifically includes the following steps:

[0038] 1) Check whether the main unit, the ultrasonic detection probe 1 (i.e., the ultrasonic detection probe of the bonding detector) and the probe cable are normal in appearance and whether the battery is sufficient, and connect the probe cable to the main unit. The ultrasonic detection probe 1 specifically includes a detection probe body and a probe signal transmitting end 5 and a probe signal receiving end 6 respectively integrated with the detection probe body. Its detection principle is: during detection, part of the sound wave 7 propagates from the probe signal transmitting end 5 to the probe signal receiving end 6, and part of the sound wave 7 propagates into the blade skin core material 4 and then reflects to the probe signal receiving end 6. Therefore, during detection, if there is a delamination defect in the blade skin, the signal waveform received by the probe signal receiving end 6 will change, so that the bonding quality of the blade skin can be non-destructively tested.

[0039] 2) After turning on the instrument by pressing and holding the power button, confirm that the connected P-C probe 1 is the correct model and select the detection mode: "Skin and core debonding (flat)".

[0040] 3) Place the transmitter-receiver probe 1 in a well-bonded position near the area to be inspected. The four support columns of the transmitter-receiver probe 1 should be fully pressed against the surface of the fiberglass reinforced plastic 2 on the outer side of the blade skin. Adjust the frequency using the instrument flywheel so that the amplitude 9 is symmetrical.

[0041] 4) Select the "RF Gain" option and adjust the gain using the flywheel of the bonding tester so that the highest wave is located between the "virtual" horizontal grid lines (the first solid line is numbered 1, and the lines are numbered downwards). At this time, part of the sound wave 7 propagates from the probe signal transmitting end 5 to the probe signal receiving end 6, and part of the sound wave 7 propagates into the blade skin core material 4 and then reflects to the probe signal receiving end 6.

[0042] 5) Reference waveform setting and threshold calibration:

[0043] Adaptive filtering technology: Utilizes built-in adaptive filters to dynamically adjust filter parameters (such as cutoff frequency and bandwidth) according to the ambient noise spectrum to ensure that valid signals can still be extracted in noisy environments. For example:

[0044] Automatically shield low-frequency mechanical vibration noise (0.1-0.5kHz) during wind field detection;

[0045] For high-frequency electromagnetic interference (such as inverter noise), enable the notch filter to eliminate interference in specific frequency bands.

[0046] Establishing a Reference Waveform: Before testing, collect waveform data from three well-bonded points (≥50mm apart) near the area to be tested and take the average value as the reference waveform. The amplitude of the reference waveform should be stable on the "imaginary" horizontal grid lines (with an error of ±10%). Adjust the frequency and gain to a symmetrical state using the bond tester's flywheel (steps 3-5).

[0047] Threshold setting basis: Through experimental verification, the critical amplitude value of delamination defect is 1.5 times the reference amplitude (i.e., more than 2 grids outside the solid line). For example:

[0048] Reference amplitude: 100% → Defect judgment threshold: ≥150% (corresponding to 2 grids outside the solid line).

[0049] 6) The four support columns of the launch-receive probe 1 should be fully pressed against the fiberglass reinforced plastic 2 on the outer side of the blade skin. If the test surface is smooth, the launch-receive probe 1 can be pushed forward continuously. If the surface condition is not good, the push will be stuck and noise will enter the instrument. At this time, it can be jumped forward in smaller intervals (about 15mm).

[0050] 7) When the sound wave 7 passes through the skin, the amplitude 9 of the well-bonded area shows a symmetrical and stable amplitude characteristic, which can be seen in Figure 2 (a) If a delamination defect 3 is present, the sound wave will be reflected and scattered at the interface, resulting in a significant increase in the amplitude at the probe signal receiving end 6, accompanied by a phase shift. This is manifested as: (a) Amplitude change: The amplitude in the delamination area increases by ≥30% compared to the baseline value (well-bonded area) (supported by experimental data); (b) Waveform distortion: The waveform symmetry is destroyed, resulting in double peaks or waveform broadening. See [1] for more information. Figure 2 (b)

[0051] In addition to amplitude changes, the following quantitative indicators are introduced to assist in defect determination:

[0052] Phase offset: The phase difference between the received signal and the reference waveform is calculated using a cross-correlation algorithm. An offset of ≥15° is considered abnormal.

[0053] Waveform energy ratio: The ratio of low-frequency energy (0-2MHz) to high-frequency energy (2-5MHz) in the delamination area is increased by ≥20% compared with the baseline value.

[0054] 8) Move the side of the transmitter-receiver probe 1 marked with a white line from the area with good bonding quality toward the area to be inspected. When the amplitude 9 is located on the solid amplitude boundary 8, it indicates that a delamination defect 3 exists in the area to be inspected, and the white line on the side of the transmitter-receiver probe 1 is the boundary of the delamination defect 3 in the area to be inspected.

Claims

1. A method for detecting delamination of a wind turbine blade skin, characterized in that: The ultrasonic testing probe of the bonding tester is used to test the bonding quality of the blade skin. By analyzing the morphological differences between the received wave and the reference wave, the area with delamination defects on the blade skin is identified. The specific steps include the following: Press the ultrasonic testing probe onto the fiberglass reinforced plastic outside the blade skin; Push the ultrasonic detection probe forward continuously and when the push is stuck, push the ultrasonic detection probe forward in a jump; When the received wave waveform is symmetrical and has a stable amplitude, it indicates that the bonding quality of the blade skin is good; When the amplitude of the received wave increases and is accompanied by a phase shift, and the amplitude increase of the received wave relative to the reference wave is ≥30%, the phase shift of the received wave relative to the reference wave is ≥15°, and the waveform energy ratio increase of the received wave relative to the reference wave is ≥20%, it indicates that there is a delamination defect in the blade skin; the waveform energy ratio is the ratio of low-frequency energy to high-frequency energy.

2. The wind turbine blade skin delamination detection method according to claim 1, characterized in that: The reference wave is obtained in the following way: Select three or more sites with good bonding quality near the blade skin area to be inspected and record them as reference wave collection points; Use ultrasonic detection probe to collect waveform data at each reference wave collection point; The obtained waveform data is averaged to obtain the reference wave waveform, and the amplitude of the reference wave is ensured to be basically stable between the virtual horizontal grid lines. Adjust the frequency and gain of the reference wave to make it symmetrical.

3. The wind turbine blade skin delamination detection method according to claim 2, characterized in that: The distance between each reference wave collection point is ≥50mm.

4. The wind turbine blade skin delamination detection method according to claim 2, characterized in that: The amplitude of the reference wave has an error of ±10% relative to the imaginary horizontal grid lines.

5. The wind turbine blade skin delamination detection method according to claim 2, characterized in that: When pressing the ultrasonic detection probe against the fiberglass reinforced plastic on the outside of the blade skin, the four support columns at the bottom of the ultrasonic detection probe should be completely pressed against the surface of the fiberglass reinforced plastic on the outside of the blade skin.

6. The wind turbine blade skin delamination detection method according to claim 5, characterized in that: At the initial moment of testing the bonding quality of the blade skin, it is necessary to adjust the frequency through the instrument flywheel of the bonding tester so that the waveform of the received wave is symmetrical on the left and right.

7. The wind turbine blade skin delamination detection method according to claim 5, characterized in that: At the initial moment of testing the bonding quality of the blade skin, it is necessary to select the RF gain item of the bonding tester and adjust the gain through the instrument flywheel so that the amplitude of the received wave is between the virtual horizontal grid lines.

8. The wind turbine blade skin delamination detection method according to claim 1, characterized in that: When there is a delamination defect in the blade skin, the critical amplitude value of the received wave is 1.5 times the amplitude of the reference wave.

9. The wind turbine blade skin delamination detection method according to claim 1, characterized in that: During the inspection of the bonding quality of the blade skin, the side of the ultrasonic detection probe engraved with a white line is moved from the area with good bonding quality of the blade skin to the area to be inspected. When the amplitude of the received wave is on the solid line, it indicates that there is a delamination defect in the area to be inspected, and the side of the ultrasonic detection probe engraved with a white line is the boundary of the delamination defect in the area to be inspected.

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