Method for determining evaluation threshold value for fan blade edge bonding defect detection

Abstract

This invention provides a method for determining the evaluation threshold value for detecting bonding defects in fan blade edging, relating to the field of fan blade inspection technology. The method for determining the evaluation threshold value for detecting bonding defects in fan blade edging provided by the embodiments of this invention uses a fan blade with defects for inspection, without using artificial test blocks. Therefore, it avoids the problem that defects created on artificial test blocks cannot represent the actual debonding defects in the edging, leading to either missed defects or overly strict defect assessments, thereby effectively improving the accuracy of the inspection and evaluation results.

Description

Technical Field

[0001] This invention relates to the field of fan blade inspection technology, and more specifically, provides a method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades. Background Technology

[0002] The demand for higher, faster, and quieter flight in civil aircraft engines has placed new requirements on their power and efficiency. Building upon advancements in aerodynamic design, structural design, and composite material technology, the application of composite fan blades can further improve the thrust-to-weight ratio and fuel efficiency of commercial aircraft, reduce noise and harmful gas emissions, and increase comfort and economy. Moreover, composite fan blades offer significant advantages compared to traditional titanium alloy fan blades. To prevent delamination of the composite adhesive layer during operation and damage from bird strikes, titanium alloy edging is added to the leading and trailing edges of the blade, bonded using an adhesive film. In other words, current composite fan blades, in addition to the composite blade body, also have metal edging bonded to the leading and trailing edges of the blade body.

[0003] Due to the harsh operating conditions, composite fan blades require high-quality edge bonding. Currently, the industry uses ultrasonic penetration testing to inspect the edge bonding quality of composite fan blades. However, the artificially manufactured comparison blocks in existing technologies are insufficient to represent the actual debonding defects of the edge bonding. This leads to inaccurate test results when using ultrasonic penetration testing to evaluate the edge bonding quality, resulting in either missed defects or overly strict defect assessments. Consequently, this poses a significant risk to the use of the parts or results in substantial waste of testing costs. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades. This method obtains the evaluation threshold value by detecting real defects, thereby avoiding problems such as missed defects and overly strict defect judgments caused by the inability of manually compared test blocks to represent real debonding defects. This helps to improve the accuracy of the detection and evaluation results.

[0005] The evaluation threshold value determination method for detecting defects in the edge bonding of fan blades provided by this invention can be implemented in the following manner:

[0006] A method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades, comprising:

[0007] Defect detection is performed on the defective fan blades to obtain defect information of the fan blades;

[0008] The fan blades were evaluated using multiple threshold values, and multiple defect results were obtained.

[0009] The multiple defect results are compared with the defect information, and the threshold value corresponding to the defect result that is closest to the defect information is used as the evaluation threshold value.

[0010] The defect information includes the location and size information of the defect.

[0011] Optionally, the step of performing defect detection on the defective fan blades to obtain defect information of the fan blades includes:

[0012] Determine the sampling location;

[0013] Dissection and sampling were performed at the sampling location to obtain multiple samples;

[0014] Micro-nano CT was used to detect the multiple samples separately to obtain the defect information.

[0015] Optionally, the step of determining the sampling location includes:

[0016] The ultrasonic anomaly region and the industrial CT anomaly region of the defective fan blade are obtained, and the sampling location includes the ultrasonic anomaly region and the industrial CT anomaly region.

[0017] Optionally, the sampling location may also include a location within a blank area, which is simultaneously a region without ultrasound abnormalities and a region without industrial CT abnormalities.

[0018] Optionally, before the step of performing defect detection on the defective fan blades to obtain defect information of the fan blades, the method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades further includes the step of selecting the defective fan blades.

[0019] Optionally, the step of selecting defective fan blades includes:

[0020] Multiple fan blades were tested using the penetration ultrasonic testing method, and evaluated according to preset threshold values ​​to obtain multiple evaluation results.

[0021] Based on the evaluation results, the defective fan blades are selected from the plurality of fan blades.

[0022] Optionally, the step of selecting the defective fan blade from the plurality of fan blades based on the evaluation results includes:

[0023] Based on the evaluation results, fan blades with abnormal ultrasonic attenuation signals were selected from multiple fan blades.

[0024] The fan blade with the largest defect size under the same abnormal ultrasonic attenuation signal is considered to have the defect.

[0025] Optionally, the method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades further includes a verification step for verifying the defect information.

[0026] Optionally, the verification step includes: verifying the defect information using metallographic testing.

[0027] The beneficial effects of the evaluation threshold value determination method for detecting bonding defects in fan blade edge wrapping provided by the embodiments of the present invention include, for example:

[0028] This invention provides a method for determining an evaluation threshold value for detecting defects in the edge bonding of fan blades. The method includes: performing defect detection on a defective fan blade to obtain defect information; evaluating the fan blade using multiple threshold values ​​to obtain multiple defect results corresponding one-to-one with each threshold value; finally, comparing the multiple defect results with the defect information to identify the defect result closest to the information, and using the threshold value corresponding to this defect result as the evaluation threshold value. This evaluation threshold value can then be used to perform ultrasonic penetration testing on other fan blades with a structure substantially identical to the one used in the above determination process. Because this method for determining an evaluation threshold value for detecting defects in the edge bonding of fan blades does not use artificial test blocks but instead uses a defective fan blade, it avoids the problem that defects created on artificial test blocks are difficult to represent the actual debonding defects of the edge bonding, thus preventing missed defects or overly strict defect assessments. This effectively improves the accuracy of the detection and evaluation results. Attached Figure Description

[0029] The above-described features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present invention in conjunction with the following accompanying drawings.

[0030] Figure 1 A flowchart is shown of a method for determining an evaluation threshold value for detecting defects in the edge bonding of fan blades, according to one aspect of the present invention.

[0031] Figure 2 An ultrasound C-scan evaluation diagram from an embodiment of the present invention is shown.

[0032] Figure 3 A CT scan image is shown in an embodiment of the present invention.

[0033] Figure 4 The image shown is a micro / nano CT rendering of sample No. 2 in an embodiment of the present invention.

[0034] Figure 5 An ultrasound C-scan evaluation map obtained according to the evaluation threshold value is shown in an embodiment of the present invention. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0036] In the content described in this invention, "penetrating ultrasonic testing" refers to a method that uses a transmitter and a receiver dual probe placed on opposite sides of a test piece to detect defects in the test piece based on the energy change after penetrating the test piece; "threshold value" refers to the attenuation amount set in penetrating ultrasonic testing, mainly based on the amplitude characteristics of the transmitted sound wave received by the receiving transducer.

[0037] Meanwhile, the "fan blade" referred to in this invention refers to a fan blade with metal edging bonded to the front and rear edges of the composite material blade body; "inspection" mainly refers to the inspection of the edging area.

[0038] Figure 1 This is a flowchart illustrating the method for determining the evaluation threshold value for detecting adhesion defects in fan blade edging, provided by this invention. Please refer to... Figure 1 The method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades provided by this invention includes the following steps:

[0039] S1: Select fan blades with defects.

[0040] To ensure that the fan blades used for inspection are defective and to improve the accuracy of subsequent inspections, defective fan blades that meet the requirements can be pre-selected from a pool of blades for later steps. Obviously, if the obtained fan blades have already been confirmed to be defective, this selection step can be omitted.

[0041] Optionally, the selection process involves using ultrasonic penetration testing to inspect multiple fan blades and evaluating them according to a preset threshold value to obtain multiple evaluation results. These multiple evaluation results correspond one-to-one with multiple fan blades, and then the defective fan blades are selected from them based on the evaluation results.

[0042] Specifically, twelve fan blades can be set, and the edge banding of these twelve fan blades can be inspected using the penetration ultrasonic testing method. The commonly used threshold value of 10dB is used for evaluation to obtain the evaluation results. That is, in this embodiment, the preset threshold value is 10dB. It can be understood that in other embodiments, other values ​​can also be used as the preset threshold value according to the actual situation.

[0043] Based on the evaluation results, firstly, all fan blades with abnormal ultrasonic attenuation signals were selected from the twelve fan blades, and then the one with the largest defect size under the same abnormal ultrasonic attenuation signal was identified as the defective fan blade.

[0044] For example, after evaluation based on a preset threshold of 10dB, the ultrasonic attenuation anomaly signals include attenuation values ​​of 10dB, 11dB, and 13dB. Then, the largest defect size is selected from the anomalies with an ultrasonic attenuation signal of 10dB, the largest defect size from the anomalies with an ultrasonic attenuation signal of 11dB, and the largest defect size from the anomalies with an ultrasonic attenuation signal of 13dB. This process selects three representative anomalies, and fan blades exhibiting these three anomalies are considered defective. Therefore, the number of fan blades selected as defective is 1-3. Specifically, if the three anomalies are distributed on different fan blades, the number of defective fan blades selected is three; if two of the three anomalies are distributed on one fan blade and the other on another fan blade, the number of defective fan blades selected is two; if all three anomalies are distributed on the same fan blade, the number of defective fan blades selected is one.

[0045] It should be noted that there is no limitation on the number of fan blades to be selected. It is understood that in other embodiments, the number of fan blades to be selected can also be set as needed. For example, the number of fan blades can be set to ten, so that defective fan blades can be selected from the ten fan blades based on the evaluation results of the penetration ultrasonic test.

[0046] It should also be noted that if multiple defective fan blades are selected, all of these defective fan blades must be inspected in subsequent steps.

[0047] S2: Perform defect detection on the defective fan blades to obtain defect information about the fan blades.

[0048] By inspecting the defective fan blades, information about the defects in the fan blades is obtained. Specifically, step S2 can be implemented according to the following steps:

[0049] S21: Determine the sampling location.

[0050] The ultrasonic and industrial CT abnormality areas of the defective fan blades are obtained. These areas represent the areas in the fan blades where defects may exist. Therefore, sampling is required in each ultrasonic and industrial CT abnormality area. In other words, the sampling locations include both ultrasonic and industrial CT abnormality areas.

[0051] Specifically, since the fan blades were inspected using ultrasonic penetration in step S1, the ultrasonic anomaly area can be obtained based on the evaluation results obtained in step S1. Clearly, if step S1 is omitted in the execution of this method for determining the evaluation threshold value for detecting defects in fan blade edge bonding, then in step S21, the defective fan blades need to be ultrasonically inspected, and a commonly used threshold value (e.g., 10 dB) needs to be used for evaluation to obtain the ultrasonic anomaly area.

[0052] Furthermore, industrial CT is used to inspect the defective fan blades to obtain the industrial CT anomaly areas of the defective fan blades.

[0053] Specifically, the resolution of the industrial CT can be optionally set to 138 micrometers. The industrial CT is used to inspect the selected defective fan blades, which can further identify areas that may have defects, i.e., abnormal areas of the industrial CT, thus avoiding missed detections caused by inaccurate preset threshold values ​​during ultrasonic testing.

[0054] Furthermore, the sampling location also includes areas within blank regions. Blank regions are those that simultaneously belong to areas without ultrasound anomalies and areas without industrial CT anomalies; in other words, blank regions are neither ultrasound anomaly areas nor industrial CT anomaly areas. Thus, blank samples obtained by setting them within blank regions help enhance the confidence level of subsequent anatomical test results.

[0055] S22: Perform dissection sampling at the sampling location to obtain multiple samples.

[0056] Based on the results of the transmissive ultrasonic test and the industrial CT test, dissection and sampling are performed in each ultrasonic abnormality area and each industrial CT abnormality area. If an ultrasonic abnormality area corresponds to an industrial CT abnormality area, then a sample containing both the ultrasonic abnormality area and the industrial CT abnormality area can be obtained at that location.

[0057] Optionally, the obtained sample is a part of the ultrasonic abnormal area or the industrial CT abnormal area. For example, if a sample is dissected in a certain ultrasonic abnormal area, the obtained sample is only a part of the ultrasonic abnormal area, and the other part remains on the fan blade. In this way, if the sampling fails, the sampling can be performed again, and the fan blade with defects can be used as a natural defect test block.

[0058] Dissection and sampling are performed in the blank area to obtain at least one blank sample.

[0059] S23: Defect information is obtained by using micro-nano CT to inspect multiple samples.

[0060] Micro-nano CT was used to inspect multiple samples separately to obtain defect information. The defect information included the location and size of the defects.

[0061] Specifically, since the positions of multiple samples on a defective fan blade are unique, after confirming the presence of defects in each sample using micro-nano CT, the location information of the defects on the fan blade can be obtained. For example, if a sample has a defect, then there is a defect at the corresponding position on the fan blade; conversely, if a sample does not have a defect, it indicates that there is no defect at the corresponding position on the fan blade. Furthermore, micro-nano CT can directly obtain the size information of each defect.

[0062] S3: Verification steps.

[0063] The defect information obtained in step S23 is verified to confirm the accuracy of the results of step S23. Optionally, metallographic testing can be used for verification.

[0064] Specifically, metallographic testing is performed on multiple samples. This testing can confirm the type of defects on the samples, and correspondingly, the presence of defects can be verified based on the metallographic results. Furthermore, if the metallographic results are inconsistent with the results of micro / nano CT, further sample grinding and testing are required.

[0065] S4: Multiple threshold values ​​are used to evaluate the fan blades and obtain multiple defect results.

[0066] Since the fan blades have already been inspected using penetrating ultrasonic testing in the preceding steps, the threshold value parameter in penetrating ultrasonic testing can be adjusted to obtain the defect result corresponding to that threshold value. It is understandable that if penetrating ultrasonic testing had not been used to inspect the fan blades in the preceding steps, it could have been performed before dissection and sampling, and multiple threshold values ​​could have been used for evaluation to obtain multiple defect results.

[0067] Obviously, the evaluation threshold value determination method for detecting defects in the edge bonding of fan blades of the present invention does not limit the order of steps S2 and S4. Step S4 can be performed after step S2, before step S2, or during the execution of step S2.

[0068] S5: Compare multiple defect results with the defect information separately, and use the threshold value corresponding to the defect result that is closest to the defect information as the evaluation threshold value.

[0069] The evaluation threshold determination method for detecting edge bonding defects in fan blades provided by this invention determines the evaluation threshold by detecting defective fan blades. The defects on the fan blades are the real defects, eliminating the need for artificial test blocks with artificial defects. This avoids inaccurate evaluation results, missed defects, or overly strict defects caused by the inability of artificial test blocks to represent the real debonding defects of the edge bonding. It helps to improve the accuracy of the detection and evaluation results and reduce the risks to the use of parts or the waste of test costs.

[0070] It should be noted that if there are multiple defective fan blades selected, then in step S4, each defective fan blade needs to be evaluated using multiple threshold values. Then, in step S5, the defect results and defect information of multiple defective fan blades need to be compared to make a comprehensive judgment and determine the evaluation threshold value.

[0071] Example 1

[0072] S1: Select fan blades with defects.

[0073] A batch (e.g., twelve) of composite material fan blades were subjected to penetration ultrasonic testing. Based on a 10 dB evaluation, defective fan blades were selected and numbered 001#. In this embodiment, all selected ultrasonic anomaly areas were distributed within the same fan blade, resulting in one defective fan blade being selected. Blade numbered 001# exhibited three ultrasonic anomaly areas, as shown in its ultrasonic C-scan evaluation image. Figure 2 As shown, the three abnormal ultrasound areas are respectively Figure 2 Areas 1, 2, and 3 are included.

[0074] S2: Perform defect detection on the defective fan blades to obtain defect information of the fan blades.

[0075] Based on the evaluation results of step S1, three areas of ultrasonic anomaly were found in blade number 001#, as shown in the ultrasonic C-scan evaluation image. Figure 2 As shown, the three abnormal ultrasound areas are respectively Figure 2 Areas 1, 2, and 3 are included.

[0076] Industrial CT was used to inspect blade #001. The resolution of the industrial CT is 138 micrometers. The inspection results are as follows: Figure 3 As shown in Table 1, the comparison results between simultaneous penetrating ultrasound detection and industrial CT detection are as follows:

[0077] Table 1

[0078]

[0079] According to the results in Table 1, the industrial CT scanner detected three abnormal CT areas, and the three abnormal ultrasound areas were as follows: Figure 3 Areas 4, 5, and 6 are included. Meanwhile, area 4 is connected to... Figure 2 Area 2 corresponds to area 6, and area 6 corresponds to area 2. Figure 2 The abnormality in the location of area 3 was detected by the penetrating ultrasound method, while the abnormality in the location of area 5 was missed by the industrial CT method, which missed the abnormality in the location of area 1.

[0080] Based on the results of ultrasonic testing using the penetrating method and industrial CT scans, samples were taken from leaf 0001#, and five samples were obtained. The sampling information is shown in Table 2.

[0081] Table 2

[0082]

[0083]

[0084] Micro-nano CT (resolution 22-33 micrometers) was used to detect each sample, and the detection results are shown in Table 3. Figure 4 The following is a rendering of the micro-nano CT detection results, using sample No. 2 as an example:

[0085] Table 3

[0086] Serial Number Micro-nano CT results Sample No. 1 There is a discontinuous hole defect, approximately 6mm in length. Sample No. 2 There is a 17mm long hole defect, as shown in the rendering. Figure 4 As shown Sample No. 3 A 17mm long hole defect exists. Sample No. 4 No defects were found. Sample No. 5 There is a 12mm long hole defect.

[0087] According to the defect information obtained by micro-nano CT as shown in Table 3, there are defects in samples 1, 2, 3 and 5, that is, there are defects in regions 1, 2, 3 and 5 of the fan blade. The size information of each defect is shown in Table 3.

[0088] It should be noted that, Figure 4 The “caliper 1: 17.14mm” marked in the image refers to the actual length of the defect being 17.14mm; “5mm” is the scale bar, indicating that the actual size represented by the scale bar length in front of 5mm in the rendering image is 5mm; “3D” indicates that the image on the right is a three-dimensional view.

[0089] S3: Verification steps.

[0090] Metallographic analysis was performed on the five samples obtained in the above steps, and the results are shown in Table 4.

[0091] Table 4

[0092]

[0093]

[0094] According to Table 4, the metallographic test results show that samples 1, 2, 3 and 5 all have defects. This result is consistent with the results of micro-nano CT, indicating that the micro-nano CT test results are correct.

[0095] S4: Multiple threshold values ​​are used to evaluate the fan blades and obtain multiple defect results.

[0096] The results of the micro-nano CT scan show that using a 10dB threshold for evaluation resulted in missed defects. Therefore, re-evaluation was performed using 9dB, 8dB, 7dB, and 6dB thresholds, and ultrasound C-scans were obtained. These ultrasound C-scans represent the defect results obtained under the given threshold evaluation. Figure 5 The ultrasound C-scan image is shown when evaluation is performed at 6 dB. Figure 5 The defect results are shown when the evaluation is performed using 6dB.

[0097] S5: Compare multiple defect results with the defect information separately, and use the threshold value corresponding to the defect result that is closest to the defect information as the evaluation threshold value.

[0098] Reference Figure 5 Four defects were identified using a 6dB evaluation method. Figure 5 The defects #1, #2, #3, and #4 were compared, and the location and size of these four defects were basically consistent with the detection results of micro-nano CT. Furthermore, compared with the defect results obtained under other threshold values ​​(not shown), these four defects were closest to the detection results of micro-nano CT. Therefore, 6dB is the optimal threshold value for ultrasonic testing of edge bonding defects in this blade type using the penetration method. In other words, 6dB is set as the evaluation threshold value for edge bonding defect detection in fan blades with the same blade type as blade #0001.

Claims

1. A method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades, characterized in that, include: Defect detection is performed on the defective fan blades to obtain defect information of the fan blades; The fan blades were evaluated using multiple threshold values, and multiple defect results were obtained. The multiple defect results are compared with the defect information, and the threshold value corresponding to the defect result that is closest to the defect information is used as the evaluation threshold value. The defect information includes the location and size information of the defect; The step of performing defect detection on the defective fan blades to obtain defect information of the fan blades includes: Determine the sampling location; Dissection and sampling were performed at the sampling location to obtain multiple samples; Micro-nano CT was used to detect the multiple samples separately to obtain the defect information; The step of determining the sampling location includes: The ultrasonic anomaly region and the industrial CT anomaly region of the defective fan blade are obtained, and the sampling location includes the ultrasonic anomaly region and the industrial CT anomaly region. The sampling location also includes locations within blank areas, which are simultaneously areas without ultrasound abnormalities and areas without industrial CT abnormalities.

2. The method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades according to claim 1, characterized in that, Before the step of performing defect detection on the defective fan blades to obtain defect information of the fan blades, the method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades further includes the step of selecting the defective fan blades.

3. The method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades according to claim 2, characterized in that, The step of selecting defective fan blades includes: Multiple fan blades were tested using the penetration ultrasonic testing method, and evaluated according to preset threshold values ​​to obtain multiple evaluation results. Based on the evaluation results, the defective fan blades are selected from the plurality of fan blades.

4. The method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades according to claim 3, characterized in that, The step of selecting the defective fan blade from the plurality of fan blades based on the evaluation results includes: Based on the evaluation results, fan blades with abnormal ultrasonic attenuation signals were selected from multiple fan blades. The fan blade with the largest defect size under the same abnormal ultrasonic attenuation signal is considered to have the defect.

5. The method for determining the evaluation threshold value for detecting bonding defects in fan blade edge banding according to any one of claims 1-4, characterized in that, The method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades also includes a verification step for verifying the defect information.

6. The method for determining the evaluation threshold value for detecting defects in the edge bonding of fan blades according to claim 5, characterized in that, The verification steps include: Metallographic testing was used to verify the defect information.

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