Test block for air coupling ultrasonic detection and manufacturing method thereof

Abstract

The invention discloses a test block for air coupling ultrasonic detection and a manufacturing method of the test block. The test block comprises a target test block raw material and a first adhesive tape adhered to the first surface of the target test block raw material, the first adhesive tape has a target material and a target thickness; the first adhesive tape is provided with an adhesive surface and a non-adhesive surface; the adhesive surface of the first adhesive tape comprises a first area and a second area, the first area surrounds the second area, the first area is bonded with the first surface through an adhesive layer, and an air gap is formed between the second area and the first surface; the thickness and the material of the target test block raw material and the curvature of the first surface are consistent with those of the to-be-detected piece.

Description

Technical Field

[0001] The present application relates to the field of nondestructive testing, and in particular to a test block for air-coupled ultrasonic testing and a method for making the same. Background Art

[0002] During ultrasonic testing, a test block with known size defects is required as a comparison to determine the test system settings for actual part testing and the comparative evaluation of defects in the test results. In the prior art, defects with known sizes are generally pre-set on the test block by pre-embedding, digging holes, or externally pasting.

[0003] Air-coupled ultrasound is a new ultrasonic detection method that uses a special ultrasonic probe to directly use air as the coupling medium. Compared with traditional ultrasound, air-coupled ultrasound detection does not require the use of liquid coupling such as water and oil. It is particularly suitable for ceramic-based composites, porous bulletproof fiberboard, foam and other water-absorbing materials. It can also be used as an alternative detection method for resin-based composites, thin metals and other materials that can be detected by traditional water-coupled ultrasound.

[0004] Delamination is the most common defect in the above materials, which is characterized by a flaky air layer inside the material. In order to detect delamination defects, it is necessary to prepare artificial defects with the same or similar properties on the test block. Existing methods generally preset delamination defects by filling foreign objects or removing materials at specific locations. This method of presetting defects is relatively cumbersome. Summary of the invention

[0005] To this end, this application discloses the following technical solutions:

[0006] In a first aspect, the present application provides a test block for air-coupled ultrasonic testing, comprising a target test block raw material and a first adhesive tape adhered to a first surface of the target test block raw material;

[0007] The first adhesive tape has a target material and a target thickness;

[0008] The first adhesive tape has an adhesive surface and an adhesive-free surface;

[0009] The adhesive surface of the first adhesive tape includes a first area and a second area, the first area surrounds the second area, the first area is bonded to the first surface via an adhesive layer, and there is an air gap between the second area and the first surface;

[0010] The thickness, material and curvature of the first surface of the raw material of the target test block are consistent with those of the object to be tested.

[0011] Optionally, in the adhesive surface of the first adhesive tape, there is an adhesive layer in the first area, and there is no adhesive layer in the second area.

[0012] Optionally, the test block further includes a second adhesive tape, the second adhesive tape has an adhesive surface and an adhesive-free surface, and the area of ​​the adhesive surface of the second adhesive tape is consistent with the area of ​​the second region;

[0013] The adhesive surface of the second adhesive tape and the second area of ​​the first adhesive tape are bonded together by respective adhesive layers.

[0014] Optionally, the target test block raw material is a test block raw material that satisfies the first condition among a plurality of candidate test block raw materials;

[0015] The first condition includes:

[0016] The C-scan test was performed on the raw materials of the test block using an air-coupled ultrasonic testing system. The test block raw materials did not have an area where the signal amplitude was lower than the average signal amplitude by 3 dB, and did not have an area where the signal amplitude was higher than the average signal amplitude by 3 dB.

[0017] Optionally, the distance from the edge of the second area to the edge of the first tape is greater than a preset first distance threshold.

[0018] Optionally, the target material and the target thickness are the material and thickness that satisfy the second condition;

[0019] The second condition includes:

[0020] When the tape of the target material and the target thickness is bonded to the first surface of the raw material of the target test block and there is no air layer between the tape and the first surface, a C-scan test is performed to obtain an A-scan waveform after the tape is bonded. The A-scan waveform after the tape is bonded is less than 2dB in the transmission wave peak value compared to the A-scan waveform before the tape is bonded.

[0021] Optionally, the distance from the edge of the first tape to the edge of the target test block raw material is greater than a preset second distance threshold.

[0022] Optionally, the first adhesive tape is provided in multiple pieces;

[0023] The distance between the edges of any two pieces of the first adhesive tape is greater than a preset third distance threshold.

[0024] Optionally, the second area is any one of a circular area, a triangular area and a square area.

[0025] The second aspect of the present application provides a method for manufacturing a test block for air-coupled ultrasonic testing, comprising:

[0026] Determine, based on the test piece, a target test block raw material whose thickness, material and curvature of the first surface are consistent with those of the test piece;

[0027] Obtaining a first adhesive tape having a target material and a target thickness, wherein the first adhesive tape has an adhesive surface and an adhesive-free surface, wherein the adhesive surface of the first adhesive tape includes a first region and a second region, wherein the first region surrounds the second region, the first region can be bonded to the target test block raw material through an adhesive layer, and the second region cannot be bonded to the target test block raw material through an adhesive layer;

[0028] The first adhesive tape is bonded to the first surface of the target test block raw material to obtain a test block for air-coupled ultrasonic testing.

[0029] The beneficial effect of the present application is that it utilizes the characteristic that air-coupled ultrasound is insensitive to thin layers of tape firmly attached to the outside. By removing the adhesive layer or the adhesive layer of the tape, a very thin air gap is preset on the surface of the material to simulate the internal stratification defects, overcoming the difficulties in making traditional pre-embedded defects, and the different properties of external defects and actual stratification defects. The defects preset by this method are consistent with the properties of the real stratification, and are simple to prepare, extremely low in cost, and easy to use. It is particularly suitable for porous materials such as ceramic-based composites, bulletproof fibers, foams, etc. that can only be detected by air-coupled ultrasound, and can also be used for materials such as resin-based composites that can be detected by both traditional liquid-coupled ultrasound and air-coupled ultrasound. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0031] Figure 1 It is a schematic diagram of the structure of a test block for air-coupled ultrasonic testing provided in an embodiment of the present application;

[0032] Figure 2 It is a schematic diagram of the adhesive surface of the first adhesive tape in a test block for air-coupled ultrasonic testing provided in an embodiment of the present application;

[0033] Figure 3 It is a flow chart of a method for manufacturing a test block for air-coupled ultrasonic testing provided in an embodiment of the present application. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] The present application provides a test block for air-coupled ultrasonic testing (hereinafter referred to as the test block). The structure of the test block can be seen in Figure 1 .

[0036] like Figure 1 As shown in (1), the test block of this embodiment includes a target test block raw material 2 and a first adhesive tape 1 adhered to a first surface of the target test block raw material. Figure 1 (1) is a top view of a test block of this embodiment.

[0037] The first tape has a target material and a target thickness t2.

[0038] The first adhesive tape has an adhesive side and an adhesive-free side, see Figure 1 of (2) and (4), Figure 1 (2) is the AA cross-section of the test block. Figure 1 (4) is a top view of the adhesive surface of the first adhesive tape, the adhesive surface and the non-adhesive surface of the first adhesive tape are opposite, and the adhesive surface 1-1 is in contact with the first surface 2-1 of the target test block raw material. The target test block raw material has a first surface 2-1 and a second surface 2-2 opposite to the first surface.

[0039] The adhesive surface of the first adhesive tape includes a first area 1-2.1 and a second area 1-2.2, and the first area surrounds the second area, for example Figure 1 In (4), the second area is located at the center of the adhesive surface, and the first area is located at the periphery of the adhesive surface.

[0040] For further information, see Figure 1 (3) is Figure 1 From the partial enlarged view of area B in the cross-sectional view of (2), it can be seen that there is an adhesive layer between the first area of ​​the first tape and the first surface, the first area is bonded to the first surface through the adhesive layer, and the second area is not bonded to the first surface through the adhesive layer, so there is an air gap between the second area and the first surface.

[0041] The thickness t1, material and curvature of the first surface of the target test block raw material contained in the test block of this embodiment are consistent with those of the test piece.

[0042] For example, if a workpiece made of a ceramic-based composite material X needs to be inspected, then the material of the raw material of the target test block is also the ceramic-based composite material X. If the workpiece is a sheet workpiece with a thickness of 20 centimeters (cm), then the thickness t1 of the raw material of the target test block is also 20 cm. If the sheet workpiece has a certain curvature y, then the raw material of the target test block also has a curvature y.

[0043] The test block provided in this embodiment is used to simulate internal delamination defects by pasting tape on the surface of the raw material of the target test block to set the threshold air gap, thus overcoming the difficulties in making traditional pre-embedded defects and the different properties of external defects and actual delamination defects. The defects preset by this method are consistent with the properties of the actual delamination, and the preparation is simple, the cost is extremely low, and the application is convenient. It is particularly suitable for porous materials such as ceramic-based composite materials, bulletproof fibers, and foams that can only be detected by air-coupled ultrasonic testing, and can also be used for materials such as resin-based composite materials that can be detected by both traditional liquid-coupled ultrasonic testing and air-coupled ultrasonic testing.

[0044] The test block and the manufacturing method thereof provided in the embodiment of the present invention are particularly suitable for air-coupled ultrasonic testing of porous materials such as ceramic-based composite materials, bulletproof fibers, and foams. Other materials that can be tested by air-coupled ultrasonic testing, such as resin-based composite materials and thin metal plates, can also be used, belonging to the field of non-destructive testing.

[0045] It should be noted that when performing C-scan testing on a test block for air-coupled ultrasonic testing, it should be ensured that the probe axis is always perpendicular to the first surface of the target test block material during the entire scanning process, that is, the probe axis is parallel to the normal of the first surface.

[0046] This embodiment does not limit the shape of the target test block raw material, which can be Figure 1 The square piece shown may also be a circular piece, a triangular piece, etc., without limitation.

[0047] In some embodiments, in order to facilitate detection, a lower limit of the size of the target test block raw material can be set. For example, the lower limit of the size can be set to 100 millimeters (mm). Specifically, for a square sheet-shaped target test block raw material, its length and width can be limited to not less than 100 mm. If the sheet has a certain curvature, its projected length and width can be limited to not less than 100 mm. For a circular sheet-shaped target test block raw material, its diameter or projected diameter can be limited to not less than 100 mm.

[0048] In some embodiments, a 200 mm*200 mm flat plate may be selected as the target test block raw material.

[0049] In the test block provided in this embodiment, the target test block raw material contained therein may be a test block raw material that satisfies the first condition and is selected from a plurality of candidate test block raw materials.

[0050] Exemplarily, for a certain part to be tested, materials from the same batch as the part to be tested can be selected to prepare several alternative test block raw materials according to the restrictions on curvature, thickness and size in the aforementioned embodiments, and then each alternative test block raw material is tested to see whether it meets the first condition, and finally a piece of alternative test block raw material that meets the first condition is selected as the target test block raw material.

[0051] The first condition may include:

[0052] The C-scan test was performed on the raw materials of the test block using an air-coupled ultrasonic testing system. The test block raw materials did not have an area where the signal amplitude was lower than the average signal amplitude by 3 dB, and did not have an area where the signal amplitude was higher than the average signal amplitude by 3 dB.

[0053] The above average signal amplitude refers to the average value of the amplitudes of all signals obtained by scanning all positions of the first surface of the raw material of the candidate test block.

[0054] Optionally, the 3dB in the first condition may also be set to other thresholds, such as 4dB, 5dB, etc., without limitation.

[0055] Exemplarily, the first condition may be that an air-coupled ultrasonic testing system is used to perform a C-scan test on the test block raw material, and there is no area in the test block raw material where the signal amplitude is lower than the average signal amplitude by 5 dB, and there is no area where the signal amplitude is higher than the average signal amplitude by 5 dB.

[0056] Before testing the raw materials of the candidate test blocks, the probes can be selected as follows:

[0057] Place any candidate test block raw material horizontally and between an air-coupled ultrasonic transmitting probe and an air-coupled ultrasonic receiving probe of frequency f, with the axes of the two probes overlapping and perpendicular to the first surface of the candidate test block raw material, and the distance between the transmitting probe and the candidate test block raw material equal to the focus or near field length of the transmitting probe, and adjust the distance between the receiving probe and the candidate test block raw material until the receiving wave height is maximized and the receiving probe does not collide with the candidate test block raw material during plane scanning;

[0058] Then, the air-coupled ultrasonic testing system is turned on, and its gain is adjusted so that the strength of the received signal (expressed as voltage) reaches a specific voltage threshold. If the strength of the received signal can reach the voltage threshold by adjusting the gain, the air-coupled ultrasonic transmitting probe and the air-coupled ultrasonic receiving probe with a frequency of f can be used to detect the raw materials of the candidate test block;

[0059] If the voltage threshold condition is still not met when the gain reaches the maximum, the maximum gain can be used, and the signal-to-noise ratio of the received signal at the maximum gain can be detected to be greater than or equal to a specific signal-to-noise ratio threshold. If it is greater than the signal-to-noise ratio threshold, an air-coupled ultrasonic transmitting probe and an air-coupled ultrasonic receiving probe with a frequency of f can be used to detect the raw materials of the candidate test block. If the signal-to-noise ratio is less than the signal-to-noise ratio threshold at the maximum gain, a probe with a lower frequency can be selected to make the above attempt until a probe with a certain frequency meets the above voltage threshold condition or meets the above signal-to-noise ratio threshold condition.

[0060] The voltage threshold may be set to 800 mV, or may be set to 80% of the saturation voltage of an AD card (an analog-to-digital conversion device), and the signal-to-noise ratio threshold may be set to a signal-to-noise ratio of 6 dB.

[0061] In some embodiments, a 200 kHz air-coupled ultrasonic transmitting probe and an air-coupled ultrasonic receiving probe may be finally selected for subsequent detection.

[0062] After selecting a transmitting probe and a receiving probe with a specific frequency in the above manner, an air-coupled ultrasonic detection system with the probe can be used to perform a C-scan detection on the first surface of each candidate test block raw material to obtain the signal amplitude of each area on each candidate test block raw material.

[0063] For each candidate test block raw material, if the candidate test block raw material does not have a signal amplitude lower than the average signal amplitude by 3dB, and does not have an area where the signal amplitude is higher than the average signal amplitude by 3dB, then the candidate test block raw material can be selected as the target raw material. If the candidate test block raw material has an area where the signal amplitude is lower than the average signal amplitude by 3dB, or has an area where the signal amplitude is higher than the average signal amplitude by 3dB, then other candidate test block raw materials are replaced for testing, and the candidate test block raw material is discarded.

[0064] In this embodiment, the target material and target thickness of the first tape may be the material and thickness that satisfy the second condition. That is, it is possible to detect whether multiple tapes of different thicknesses and materials satisfy the second condition. If it is detected that a certain tape satisfies the second condition, it can be determined that the material of the tape is the target material and the thickness of the tape is the target thickness.

[0065] The second condition may include:

[0066] When a tape of target material and target thickness is bonded to the first surface of the target test block raw material and there is no air layer between the tape and the first surface, a C-scan test is performed to obtain an A-scan waveform after bonding the tape. The A-scan waveform after bonding the tape has a transmission wave peak value change of less than 2dB relative to the A-scan waveform before bonding the tape.

[0067] Specifically, a tape with a thickness of t, a length of c, and a width of d can be firmly adhered to a partial area of ​​the first surface of the screened target test block raw material to ensure that there is no air layer between the tape and the target test block raw material, and then the target test block raw material after the tape is adhered is re-performed with a C-scan test using a probe of a specific frequency determined in the aforementioned embodiment, and the A-scan waveform at the position where the tape is adhered and the A-scan waveform after the tape is adhered are compared. If the comparison finds that the peak value of the transmitted wave in the A-scan waveform before and after the tape is adhered is greater than or equal to 2dB, it can be determined that the tape does not meet the second condition. At this time, tapes of other thicknesses (generally the thickness can be reduced) and materials can be replaced to repeat the above test until it is detected that a piece of tape meets the above second condition. At this time, the thickness of the tape that meets the second condition can be determined as the target thickness t2, and the material of the tape that meets the second condition can be determined as the target material.

[0068] Generally, the target thickness t2 of the first tape may be between 0.01 mm and 0.2 mm, and the target material of the first tape may be paper, polymer material or opaque material, and cloth tape or metal tape is generally not used.

[0069] The adhesive tapes used in this embodiment are all single-sided adhesive tapes, that is, they are divided into an adhesive side and a non-adhesive side.

[0070] The threshold value of 2dB of the change in the peak value of the transmission wave in the second condition can also be set to other values ​​according to actual needs, such as 3dB, 4dB, etc., and is not limited to 2dB. For example, the second condition can be that the change in the peak value of the transmission wave is less than 4dB.

[0071] Optionally, in the adhesive surface of the first adhesive tape, there is an adhesive layer in the first area, and there is no adhesive layer in the second area.

[0072] That is, after determining the target thickness and the target material, a piece of tape having the target thickness and the target material and having a suitable shape and size can be cut out first, and the adhesive surface of the tape can be divided into a first area and a second area.

[0073] Then, the adhesive layer in the second area can be removed, and the adhesive layer in the first area can be retained, so that a piece of adhesive tape without an adhesive layer in the second area is obtained. Figure 1 The first tape is shown.

[0074] There is no limitation on the method of removing the adhesive layer. For example, a physical method such as scraping with a blade or a chemical method such as dissolving with an adhesive remover can be used.

[0075] Since the adhesive layer in the second area is removed, when the first adhesive tape is bonded to the first surface of the target test block raw material, a certain air gap will be retained between the surface of the first adhesive tape in the second area and the first surface, thereby simulating a delamination defect.

[0076] Optionally, the test block of this embodiment further includes a second adhesive tape, the second adhesive tape has an adhesive surface and an adhesive-free surface, and the area of ​​the adhesive surface of the second adhesive tape is consistent with the area of ​​the second region;

[0077] The adhesive surface of the second adhesive tape and the second area of ​​the first adhesive tape are bonded together through respective adhesive layers.

[0078] That is to say, after the adhesive surface of the first tape is divided into the first area and the second area, a second tape with the same area as the first area can be cut and pasted to the second area of ​​the first tape, and the pasting method is that the adhesive surface of the second tape is in contact with the second area of ​​the first tape, so that the adhesive layer of the adhesive surface of the second tape and the adhesive layer of the second area of ​​the first tape can be bonded to each other. In this way, when the first tape is bonded to the first surface, the non-adhesive surface of the second tape will be in contact with the first surface, so that a certain air gap is left between the non-adhesive surface and the first surface, thereby achieving the effect of simulating delamination defects.

[0079] The thickness of the second tape may be the same as that of the first tape, or may be smaller than that of the first tape, and the material of the second tape may be the same as that of the first tape.

[0080] After obtaining the first tape, impurities on the first surface of the target test block raw material can be removed first, including but not limited to foreign matter such as water, oil, paint, etc., and then the first tape can be pasted on the first surface of the target test block raw material to form the air-coupled ultrasonic detection test block of this embodiment.

[0081] In some optional embodiments, in order to firmly adhere the first tape to the first surface, the distance from the edge of the second area to the edge of the first tape may be limited to be greater than a preset first distance threshold.

[0082] The first distance threshold can be set as needed. For example, when the adhesive layer of the first adhesive tape has a stronger adhesive ability, a smaller first distance threshold can be set. When the adhesive layer of the first adhesive tape has a weaker adhesive ability, a larger first distance threshold can be set.

[0083] As an example, the distance from any surface of the second area to any edge of the first tape (specifically any edge of the adhesive surface of the first tape) may be limited to be greater than 5 mm, that is, the first distance threshold may be 5 mm.

[0084] In some optional embodiments, the distance from the edge of the first tape to the edge of the target test block raw material is greater than a preset second distance threshold.

[0085] by Figure 1Taking (1) as an example, the distance from any edge of the first tape to the edge of the target test block raw material can be represented by d. In this embodiment, when making the test block, it should be ensured that the distance d between any edge of the tape and any edge of the test block raw material is greater than the second distance threshold. The second distance threshold can be set as needed, for example, it can be set to 30 mm.

[0086] In some optional embodiments, the number of the first adhesive tapes may be multiple, that is, multiple first adhesive tapes of different sizes and shapes may be respectively pasted on the first surface of the same target test block raw material.

[0087] Each piece of the first tape may have a second region of varying size and shape.

[0088] The thickness and material of different first adhesive tapes may be different, as long as the aforementioned second condition is met.

[0089] The distance between the edges of any two pieces of the first tape is greater than a preset third distance threshold.

[0090] The third distance threshold may be equal to 30 mm, or may be equal to 20 mm, or other values ​​set according to detection requirements.

[0091] By sticking multiple pieces of the first tape on the same target test block raw material, delamination defects of various shapes and sizes can be simulated in the same air-coupled ultrasonic testing test block, so that the test block can be reused in various scenarios, thereby improving the utilization rate of the test block.

[0092] Optionally, the second area is any one of a circular area, a triangular area and a square area.

[0093] That is to say, when making the first adhesive tape, the adhesive layer of any shape area can be removed as needed, such as removing the adhesive layer of a circular, square, regular triangle area, or any plane graphic area, and the second adhesive tape of any shape can also be pasted as needed.

[0094] The size of the second area is also not limited and can be adaptively set according to the detection requirements.

[0095] It should be noted that the adhesive surface of a first adhesive tape may have one or more second areas, and the shape and size of each second area may not be the same. It is sufficient to ensure that the distance between each second area is large enough, for example, greater than 5 mm. Figure 2 In the two second areas shown in 1-2.3 and 1-2.4, one second area is circular and the other second area is square.

[0096] Different second regions may have different structures, e.g. Figure 2In the embodiment, the second area 1-2.3 can retain an air gap with the first surface by removing the adhesive layer, and the second area 1-2.4 can retain an air gap with the first surface by sticking the second adhesive tape.

[0097] In some embodiments, if the test piece is a ceramic matrix composite material flat plate, a 200mm*200mm flat plate that is consistent with the ceramic matrix composite material flat plate in terms of material, process, thickness, etc. and meets the first condition above can be selected as the target test block raw material.

[0098] When performing scanning detection, the air-coupled ultrasonic transmitting probe and the air-coupled ultrasonic receiving probe with a frequency of 200 kHz can be selected for scanning detection in the manner of screening probes of different frequencies as described above.

[0099] The first adhesive tape selected in this embodiment may be a paper tape with a thickness of 0.1 mm, a length of 30 mm, and a width of 30 mm.

[0100] When preparing the test block, three pieces of paper tape with a side length of 30 mm and a thickness of 0.1 mm can be cut out as the first tape, and then three pieces of tape with side lengths of 5 mm, 10 mm, and 15 mm can be cut out as the second tape. The three second tapes are respectively pasted on the adhesive surfaces of the three first tapes in the above manner, ensuring that the distance between the edge of the second tape and the edge of the first tape is greater than 5 mm, and then the three first tapes are pasted to the surface of the raw material of the target test block, and ensuring that the edge of the first tape is 40 mm away from the edge of the raw material of the target test block, thereby obtaining a test block for air-coupled ultrasonic testing of ceramic-based composite materials.

[0101] In some embodiments, if the object to be tested is a bulletproof fiberboard, a 200*250mm flat plate that is consistent with the material, process, thickness and other characteristics of the bulletproof fiberboard and meets the first condition above can be selected as the target test block raw material.

[0102] When performing scanning detection, the air-coupled ultrasonic transmitting probe and the air-coupled ultrasonic receiving probe with a frequency of 140 kHz can be selected for scanning detection in the manner of screening probes of different frequencies as described above.

[0103] The first adhesive tape selected in this embodiment may be a paper tape with a thickness of 0.1 mm, a length of 40 mm, and a width of 40 mm.

[0104] When preparing the test block, 4 pieces of paper tape with a side length of 40 mm can be cut out as the first tape, and then 4 pieces of tape with side lengths of 5 mm, 10 mm, 15 mm, and 20 mm can be cut out as the second tape, and the 4 pieces of second tape are respectively pasted on the adhesive surface of the 4 pieces of first tape, ensuring that the distance between the edge of the second tape and the edge of the first tape is greater than 8 mm, and then the 4 pieces of first tape are pasted to the surface of the raw material of the target test block, and ensuring that the edge of the first tape is 30 mm away from the edge of the raw material of the target test block, thereby obtaining a test block for air-coupled ultrasonic testing of bullet-proof fiberboard.

[0105] In some embodiments, if the test piece is a composite blade, a 200*250 mm flat plate that is consistent with the composite blade in terms of material, process, thickness, etc. and meets the first condition above can be selected as the target test block raw material.

[0106] When performing scanning detection, the air-coupled ultrasonic transmitting probe and the air-coupled ultrasonic receiving probe with a frequency of 200 kHz can be selected for scanning detection in the manner of screening probes of different frequencies as described above.

[0107] The first adhesive tape selected in this embodiment may be a paper tape with a thickness of 0.1 mm, a length of 20 mm, and a width of 20 mm.

[0108] When preparing the test block, three pieces of paper tape with a side length of 25 mm can be cut out as the first tape, and a debonding agent is used to remove circular areas with diameters of 3 mm, 6 mm, and 12 mm from the center of each piece of the first tape. Then, the three pieces of the first tape are pasted to the first surface of the raw material of the target test block, ensuring that the edge of the first tape is 30 mm away from the edge of the raw material of the target test block, thereby obtaining a test block for air-coupled ultrasonic testing of composite blades.

[0109] In this embodiment, the probe used for C-scan detection can be a focused probe or a flat probe. When a focused probe is used, the distance between the transmitting probe and the test block raw material is equal to the focal length of the transmitting probe. When a flat probe is used, the distance between the transmitting probe and the test block raw material is equal to the near-field length of the transmitting probe.

[0110] This application provides a method for making a test block for air-coupled ultrasonic testing, see Figure 3 , is a flow chart of the method, and the method may include the following steps.

[0111] S301, determining, based on the test piece, a target test block raw material whose thickness, material and first surface curvature are consistent with those of the test piece.

[0112] In step S301, the method of selecting the raw material of the target test block can refer to the above-mentioned embodiment and will not be described in detail.

[0113] S302, obtaining a first adhesive tape having a target material and a target thickness, wherein the first adhesive tape has an adhesive surface and a non-adhesive surface, wherein the adhesive surface of the first adhesive tape includes a first region and a second region, wherein the first region surrounds the second region, the first region can be bonded to the target test block raw material through the adhesive layer, and the second region cannot be bonded to the target test block raw material through the adhesive layer.

[0114] In step S302, the method for determining the target material and target thickness of the first adhesive tape can refer to the above-mentioned embodiment and will not be described in detail.

[0115] Optionally, the adhesive layer in the second area can be removed, or a second adhesive tape of corresponding size can be pasted on the second area so that the second area cannot be bonded to the raw material of the target test block through the adhesive layer. For details, please refer to the description of the structure of the first adhesive tape in the above embodiment, which will not be repeated here.

[0116] S303, bonding the first adhesive tape to the first surface of the target test block raw material to obtain a test block for air-coupled ultrasonic testing.

[0117] The beneficial effect of this embodiment is that it utilizes the characteristic that air-coupled ultrasound is insensitive to thin layers of adhesive tape firmly attached to the outside, and by removing the adhesive layer or by attaching the adhesive tape layers to each other, a very thin air gap is preset on the surface of the material to simulate the internal stratification defect, overcoming the difficulties in making traditional pre-embedded defects, and the different properties of external defects and actual stratification defects. The defects preset by this method are consistent with the properties of the actual stratification, and are simple to prepare, extremely low in cost, and easy to use. It is particularly suitable for porous materials such as ceramic-based composite materials, bulletproof fibers, foams, etc. that can only be detected by air-coupled ultrasound, and can also be used for materials such as resin-based composite materials that can be detected by both traditional liquid-coupled ultrasound and air-coupled ultrasound.

[0118] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0119] For the convenience of description, the above system or device is described by dividing it into various modules or units according to its functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0120] It can be known from the description of the above implementation methods that those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product can be stored in a storage medium such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments of the present application or certain parts of the embodiments.

[0121] Finally, it should be noted that, in this article, relational terms such as first, second, third and fourth are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0122] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A test block for air-coupled ultrasonic testing, characterized in that: It includes a target test block raw material and a first adhesive tape adhered to a first surface of the target test block raw material; The first adhesive tape has a target material and a target thickness; The first adhesive tape has an adhesive surface and an adhesive-free surface; The adhesive surface of the first adhesive tape includes a first area and a second area, the first area surrounds the second area, the first area is bonded to the first surface via an adhesive layer, and there is an air gap between the second area and the first surface; The thickness, material and curvature of the first surface of the raw material of the target test block are consistent with those of the object to be tested.

2. The test block according to claim 1, characterized in that: In the adhesive surface of the first adhesive tape, there is an adhesive layer in the first region, and there is no adhesive layer in the second region.

3. The test block according to claim 1, characterized in that: The test block further includes a second adhesive tape, wherein the second adhesive tape has an adhesive surface and an adhesive-free surface, and the area of ​​the adhesive surface of the second adhesive tape is consistent with the area of ​​the second region; The adhesive surface of the second adhesive tape and the second area of ​​the first adhesive tape are bonded together by respective adhesive layers.

4. The test block according to claim 1, characterized in that: The target test block raw material is a test block raw material that satisfies the first condition among a plurality of candidate test block raw materials; The first condition includes: The C-scan test was performed on the raw materials of the test block using an air-coupled ultrasonic testing system. The test block raw materials did not have an area where the signal amplitude was lower than the average signal amplitude by 3 dB, and did not have an area where the signal amplitude was higher than the average signal amplitude by 3 dB.

5. The test block according to claim 1, characterized in that: The distance from the edge of the second area to the edge of the first tape is greater than a preset first distance threshold.

6. The test block according to claim 1, characterized in that: The target material and the target thickness are the material and thickness that satisfy the second condition; The second condition includes: When the tape of the target material and the target thickness is bonded to the first surface of the raw material of the target test block and there is no air layer between the tape and the first surface, a C-scan test is performed to obtain an A-scan waveform after the tape is bonded. The A-scan waveform after the tape is bonded is less than 2dB in the transmission wave peak value compared to the A-scan waveform before the tape is bonded.

7. The test block according to claim 1, characterized in that: The distance from the edge of the first tape to the edge of the target test block raw material is greater than a preset second distance threshold.

8. The test block according to claim 1, characterized in that: The number of the first adhesive tapes is multiple; The distance between the edges of any two pieces of the first adhesive tape is greater than a preset third distance threshold.

9. The test block according to claim 1, characterized in that: The second area is any one of a circular area, a triangular area and a square area.

10. A method for making a test block for air-coupled ultrasonic testing, characterized in that: include: Determine, based on the test piece, a target test block raw material whose thickness, material and curvature of the first surface are consistent with those of the test piece; Obtaining a first adhesive tape having a target material and a target thickness, wherein the first adhesive tape has an adhesive surface and an adhesive-free surface, wherein the adhesive surface of the first adhesive tape includes a first region and a second region, wherein the first region surrounds the second region, the first region can be bonded to the target test block raw material through an adhesive layer, and the second region cannot be bonded to the target test block raw material through an adhesive layer; The first adhesive tape is bonded to the first surface of the target test block raw material to obtain a test block for air-coupled ultrasonic testing.

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