Ultrasonic detection device and method for porosity of resin-based fiber reinforced composite material

Abstract

The invention provides an ultrasonic detection device and method for the porosity of a resin-based fiber reinforced composite material, and the method comprises the following steps: firstly, detecting a reference block by using an ultrasonic probe, carrying out linear fitting on detection data, establishing a relational expression between an ultrasonic attenuation rate alpha and the porosity phi, and then detecting a workpiece by using the ultrasonic probe. And finally, according to the relational expression and the attenuation rate alpha of the workpiece, the porosity of the workpiece is obtained. According to the method, the workpiece can be subjected to regional and in-situ pore detection, the porosity conditions of different parts of the large workpiece can be effectively detected, the problem that in a traditional detection method, local sampling testing cannot represent overall non-uniformity is solved, and comprehensive detection of the integrally-formed large-sized structure fiber composite material is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic nondestructive testing, and in particular to a porosity ultrasonic testing device and method for resin-based fiber-reinforced composite materials. Background Art

[0002] Resin-based fiber-reinforced composite materials have excellent properties such as light weight, high strength, high toughness, fatigue resistance and corrosion resistance. Fiber-reinforced composite materials are widely used in large aircraft, wind turbine blades, automotive parts, oil extraction sucker rods, power transmission cables and other fields. With the maturity of key technologies for domestic fiber manufacturing, fiber-reinforced composite materials are increasingly used in the engineering field by breaking through the low-cost manufacturing technology of fiber-reinforced composite materials. However, there are many molding processes for fiber-reinforced composite materials, which are roughly RTM, vacuum-assisted, prepreg hot pressing and other molding processes. Different processes produce different forms of defects. The main defect types are delamination, bubbles, resin-rich, fiber wrinkles, etc. Most of these defects can be effectively detected and evaluated by non-destructive testing methods.

[0003] During the manufacturing process of resin-based fiber-reinforced composite materials, sub-millimeter pores will be generated due to improper process control. The volume percentage of pores inside the resin-based fiber-reinforced composite materials is defined as the porosity of the resin-based fiber-reinforced composite materials. The size of the porosity directly affects the performance and mechanical properties of the resin-based fiber-reinforced composite materials. As the porosity increases, its mechanical properties decrease significantly. Therefore, resin-based fiber-reinforced composite materials have strict requirements on porosity in quality control. For example, the aerospace field requires that the porosity of carbon fiber reinforced composite materials is ≤2%. Currently, the main methods for detecting the porosity of resin-based fiber-reinforced composite materials are:

[0004] 1. Industrial computer tomography (CT) detection method, through density comparison test pieces, and then use industrial CT for density measurement calibration, the density resolution is not more than 0.5%, by slicing and scanning the sample to be tested, and then calculating the pore area divided by the total area of ​​pore content percentage on the image analyzer, such as patent CN107860696A.

[0005] 2. The metallographic method specified in GBT3365-2008 is to measure the percentage of the total pore area to the cross-sectional area of ​​the sample on the resin-based fiber-reinforced composite material through an optical microscope, image analyzer or transparent graph paper on the entire cross-section of the sample, which is the porosity content of the sample.

[0006] 3. The principle of the fiber reinforced plastic pore content test specified in JCT287-2010 is to measure the density of resin, fiber and fiber reinforced plastic respectively, then measure the resin content and calculate the theoretical density of the fiber reinforced plastic. The result is compared with the measured density of the fiber reinforced plastic, such as patent CN102426269A.

[0007] 4. Ultrasonic detection method, which characterizes the porosity of composite materials by the attenuation rate of ultrasonic waves in the material or the change in ultrasonic sound velocity. The method of ultrasonic detection of porosity of fiber-reinforced composite materials mainly appears in literature records and theoretical research, and there is no public standard specification yet.

[0008] The existing fiber composite material pore detection methods mainly have the following problems: 1, 2, and 3 of the above test methods are all sample-level test methods, which cannot realize in-situ pore detection and cannot be implemented in engineering applications. In addition, the tests are all local sampling tests, and the detection data can only represent the sampling location. It is impossible to characterize the unevenness in different parts of large-scale structural fiber composite materials that are integrally formed. For example, for compression-molded standard parts, it is impossible to sample and analyze the body, and only synchronous samples can be used as test specimens. The test results are different from the product itself. Summary of the invention

[0009] In view of this, the present invention aims to propose an ultrasonic porosity detection device and method for resin-based fiber-reinforced composite materials to solve the problems of existing methods for detecting the porosity of resin-based fiber-reinforced composite materials, which cannot realize in-situ porosity detection and cannot be implemented in engineering applications, and the tests are all local sampling tests, which are not suitable for large-scale structural fiber composite materials with integrated molding.

[0010] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0011] A method for ultrasonically detecting porosity of a resin-based fiber-reinforced composite material comprises the following steps:

[0012] S1: Make a comparison test block. The comparison test block and the workpiece are made using the same process and materials, and then enter S2;

[0013] S2: Test the comparison block. Use ultrasonic probes with different center frequencies to test the comparison block. Before testing, set a delay wedge on the comparison block to adjust the propagation path and time of the ultrasonic wave. Perform linear fitting on the test data in segments to establish the relationship between the ultrasonic attenuation rate α and the porosity φ in different segments, that is, α=kf n φ m +b, enter S3;

[0014] S3: Detect the workpiece. Use an ultrasonic probe to detect the workpiece. According to the ultrasonic echo center frequency X1, X2 and the anisotropy coefficient of the workpiece, the attenuation rate is obtained. , enter S4;

[0015] S4: Substitute the workpiece attenuation rate α into α=kf n φ m +b, obtain the porosity φ of the workpiece;

[0016] Among them, f is the probe frequency, k and b are constants, and the values ​​of n, m, k, and b are determined by linear fitting. F is the anisotropy coefficient of the workpiece, C is the propagation speed of ultrasound in the workpiece, and X1 and X2 are the center frequencies of ultrasonic echoes.

[0017] This method can perform regional and in-situ porosity detection on workpieces, and can effectively detect the porosity of different parts of large workpieces. It solves the problem that local sampling tests in traditional detection methods cannot characterize overall heterogeneity, and realizes comprehensive detection of large-scale integrated structural fiber composite materials.

[0018] Furthermore, in S1, three different stages of comparison test blocks are prepared, the porosity of the comparison test blocks in the first stage is 0.5%-1.5%, the porosity of the comparison test blocks in the second stage is 1.5%-3.5%, and the porosity of the comparison test blocks in the third stage is 3.5%-5%.

[0019] This setup covers a wide porosity range, ensuring the comprehensiveness and versatility of the detection method.

[0020] Furthermore, the comparison test blocks in each stage include at least three different porosities.

[0021] Setting a variety of porosities in the comparison test block can enhance the reliability of the detection method.

[0022] Furthermore, in S2, three ultrasonic probes with different frequencies are used to detect the comparison test blocks respectively.

[0023] By using ultrasonic probes of three different frequencies for detection, comprehensive information on pores of different sizes, shapes and distributions can be obtained, avoiding the omission of some pore information due to single frequency detection, thereby improving the reliability of detection.

[0024] Furthermore, in S2, the thickness of the delay wedge is H2, , where V2 is the propagation velocity of ultrasonic waves in the delay wedge, H3 is the thickness of the comparison block, and V3 is the propagation velocity of ultrasonic waves in the comparison block.

[0025] Regardless of the materials used for the comparison test block and the delay wedge, this setting can determine the appropriate delay wedge thickness based on their respective ultrasonic propagation velocities, thereby enhancing the adaptability of the detection method to different material combinations.

[0026] Further, in S1, the workpiece is made of a resin-based fiber-reinforced composite material, and the thickness of the workpiece and the comparison test block is T, 4 mm ≥ T ≥ 2 mm.

[0027] This setting enables ultrasound to fully interact with the pores within the material, producing signal changes that can be effectively detected and analyzed, making it easier to establish an accurate relationship between porosity and ultrasonic attenuation rate.

[0028] Furthermore, the thickness of the comparison test block is T±0.1 mm.

[0029] This setting can ensure the uniformity of basic parameters among different comparison test blocks, reduce interference caused by individual differences among comparison test blocks, and ensure the consistency of the detection process and results.

[0030] Furthermore, the resin ratio is ethylene resin: initiator: accelerator = 100:1.6:0.3.

[0031] This arrangement enables the ethylene resin to be fully cured under the action of the initiator and the accelerator, thereby improving the mechanical properties of the composite material and ensuring that the composite material has a stable structure and is not easily deformed or damaged when subjected to external forces.

[0032] Further, in S2, the delay wedge is made of isotropic sound-transmitting material.

[0033] The characteristic of isotropic materials is that the physical properties are the same in all directions. When the ultrasonic wave propagates in the delay wedge, the propagation speed and attenuation degree are relatively consistent regardless of the direction, ensuring that the ultrasonic wave can enter the comparison test block or workpiece in a stable state, thereby improving the detection accuracy.

[0034] A porosity ultrasonic detection device for resin-based fiber-reinforced composite materials, used in the above-mentioned detection method, comprising:

[0035] An ultrasonic probe, used for transmitting ultrasonic waves to a comparison test block or a workpiece, and receiving ultrasonic signals reflected by the comparison test block or the workpiece;

[0036] A delay wedge, an ultrasonic probe, a delay wedge and a comparison test block are sequentially arranged in contact with each other from top to bottom;

[0037] A calculation module, which establishes a relationship between ultrasonic attenuation rate α and porosity φ according to the ultrasonic signal, and obtains the attenuation rate α and porosity φ of the workpiece;

[0038] A display module is used to display the output results of the calculation module and input the user's setting values;

[0039] The control module controls the working states of the calculation module and the display module according to the signal fed back by the ultrasonic probe.

[0040] This detection device not only has a simple structure and is easy to operate, but also can ensure stable propagation of ultrasonic waves, reduce signal loss and interference, accurately calculate the attenuation rate and porosity, and ensure the accuracy of the detection results.

[0041] Compared with the prior art, the porosity ultrasonic detection device and method of the resin-based fiber-reinforced composite material of the present invention has the following advantages:

[0042] 1) This method can detect the porosity of workpieces in different regions and in situ, and can effectively detect the porosity of different parts of large workpieces, thus realizing the comprehensive detection of large-scale integrated structural fiber composite materials;

[0043] 2) It basically covers the porosity range that may appear in the actual production of resin-based fiber-reinforced composite materials. For workpieces with different porosity levels, corresponding comparison test blocks can be found for reference testing to ensure the comprehensiveness and versatility of the testing method. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of ultrasonic testing of the porosity of the resin-based fiber-reinforced composite material according to an embodiment of the present invention;

[0045] Figure 2 for Figure 1 Schematic diagram of the ultrasonic reflection signal spectrum.

[0046] Description of reference numerals:

[0047] 1. Ultrasonic probe; 2. Delay wedge; 3. Workpiece; 4. Ultrasonic signal. DETAILED DESCRIPTION

[0048] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0049] Example 1

[0050] like Figures 1-2 As shown, in this embodiment, ultrasound is used to measure the porosity of the resin-based glass fiber reinforced composite laminate, the reinforcing material is glass fiber, the ply is 0 / 90, the thickness is 5 mm, and the resin is ethylene resin, and the ratio is ethylene resin: initiator: promoter = 100:1.6:0.3.

[0051] The layup design is 0 / 90, which indicates the layup method of the glass fiber in the composite laminate. Here, "0" and "90" represent the angle between the fiber laying direction and the reference axis. 0° means that the fiber direction is parallel to the reference axis, and 90° means it is perpendicular. This design can make the composite material have more balanced mechanical properties in different directions.

[0052] The workpiece 3 is made by vacuum-assisted integrated injection molding process. The actual size of the workpiece 3 exceeds 6m. Due to the large area of ​​the workpiece 3, there will be local unevenness or porosity exceeding the standard area during the injection process. An ultrasonic probe 1 with a center frequency of 2.25MHz and a probe diameter of 0.5″ is used to detect the porosity of the workpiece 3 in different regions.

[0053] The specific testing methods for resin-based glass fiber reinforced composite laminates are as follows:

[0054] S1: making a comparison test block, which is made with the same process and material as workpiece 3;

[0055] S2: Testing the comparison test block, using ultrasonic probes 1 with center frequencies of 1.0MHz, 2.25MHz, and 3.5MHz, respectively, to test the comparison test block. Before testing, a delay wedge 2 is set on the comparison test block to adjust the propagation path and time of the ultrasonic wave, collect the ultrasonic echo signal of the comparison test block, and fit the ultrasonic echo signal to obtain the relationship between the ultrasonic attenuation rate α and the porosity φ, α=0.08f 1.2 φ 2 +0.52;

[0056] S3: Detect workpiece 3. Use ultrasonic probe 1 to detect workpiece 3. According to the center frequencies X1 and X2 of ultrasonic echo and the anisotropy coefficient of workpiece 3, the attenuation rate is obtained. ;

[0057] S4: Substitute the attenuation rate α of workpiece 3 into α=kf n φ m +b, obtain the porosity φ of workpiece 3;

[0058] Among them, f is the probe frequency, k and b are constants, and the values ​​of n, m, k, and b are determined by linear fitting. F is the anisotropy coefficient of the workpiece 3, C is the propagation speed of the ultrasonic wave in the workpiece 3, and X1 and X2 are the center frequencies of the ultrasonic echo.

[0059] In the present application, the ultrasonic probe 1 is first used to detect the comparison test block, and the detection data is linearly fitted to establish a relationship between the ultrasonic attenuation rate α and the porosity φ. Then, the ultrasonic probe 1 is used to detect the workpiece 3 to obtain the attenuation rate α of the workpiece 3. Finally, the porosity of the workpiece 3 is obtained according to the aforementioned relationship and the attenuation rate α of the workpiece. Since the comparison test block and the workpiece 3 are made of the same process and materials, the comparison test block can simulate the actual situation of the workpiece 3 to the greatest extent, so that the detection result is more in line with the actual porosity of the workpiece 3, and the error caused by material and process differences is reduced. The method can perform regional and in-situ porosity detection on the workpiece 3, and can effectively detect the porosity of different parts of a large workpiece, which solves the problem that local sampling tests cannot characterize the overall heterogeneity in traditional detection methods, and realizes comprehensive detection of large-scale integrated structural fiber composite materials, which is suitable for engineering detection.

[0060] Preferably, the ultrasonic probe 1 is not limited to the frequencies in S2.

[0061] Preferably, a broadband ultrasonic probe with a bandwidth ≥ 80% is used.

[0062] As a preferred example of the present application, in S1, three different stages of comparison test blocks are prepared respectively, the porosity of the comparison test blocks in the first stage is 0.5% to 1.5%, the porosity of the comparison test blocks in the second stage is 1.5% to 3.5%, and the porosity of the comparison test blocks in the third stage is 3.5% to 5%.

[0063] Specifically, this setting covers a wider porosity range, basically covering the porosity range that may appear in the actual production of resin-based fiber-reinforced composite materials. Workpieces 3 with different porosity levels can find corresponding comparison test blocks for reference detection, ensuring the comprehensiveness and versatility of the detection method, reducing detection errors, and realizing quantitative analysis of the porosity of composite materials in the range of 0.5% to 5%.

[0064] As a preferred example of the present application, the comparison test blocks in each stage include at least three different porosities.

[0065] Specifically, increasing the diversity of the porosity of the comparison test blocks can reduce the errors caused by a single or a small number of porosity samples. If the comparison test block has only one porosity, once the comparison test block has manufacturing defects, it will affect the reliability of the test results. Setting multiple porosities in the comparison test block can enhance the reliability of the detection method.

[0066] Preferably, the porosity in the first stage is selected to be 0.5%, 1%, and 1.4%, respectively, but not limited to these data.

[0067] As a preferred example of the present application, in S2, the thickness of the delay wedge 2 is H2, , where V2 is the propagation velocity of ultrasonic waves in the delay wedge 2, H3 is the thickness of the comparison block, and V3 is the propagation velocity of ultrasonic waves in the comparison block.

[0068] Specifically, since different materials have different effects on the ultrasonic propagation velocity, the formula takes these factors into account. Regardless of the materials used for the comparison test block and the delay wedge 2, the appropriate thickness of the delay wedge 2 can be determined based on their respective ultrasonic propagation velocities, thereby enhancing the adaptability of the detection method to different material combinations and enabling the detection method to effectively function in a variety of practical application scenarios.

[0069] When the workpiece 3 is inspected, the delay wedge 2 is also required.

[0070] As a preferred example of the present application, in S1, the workpiece 3 is made of a resin-based fiber-reinforced composite material, and the thickness of the workpiece 3 and the comparison test block is T, 4mm≥T≥2mm.

[0071] Specifically, the thickness is between 2mm and 4mm, which can ensure that the ultrasonic wave has sufficient penetration depth and attenuation when propagating in the material. If the material is too thin, the ultrasonic signal 4 does not change significantly, making it difficult to accurately detect the porosity. If the material is too thick, the signal will be over-attenuated, which will also affect the detection accuracy. This setting can enable the ultrasonic wave to fully interact with the pores in the material, generating signal changes that can be effectively detected and analyzed, making it easier to establish an accurate relationship between porosity and ultrasonic attenuation rate.

[0072] As a preferred example of the present application, the thickness of the comparison test block is T±0.1 mm.

[0073] Specifically, this setting can ensure the uniformity of basic parameters between different comparison test blocks, help reduce interference caused by individual differences of comparison test blocks when establishing the relationship between ultrasonic attenuation rate and porosity, ensure the consistency of the detection process and results, and facilitate analysis and judgment by testers.

[0074] Preferably, the thickness of the comparison test block is not greater than the thickness of a single layer of carbon fiber fabric. Considering that carbon fiber fabric is a reinforcement of the composite material and its single layer thickness is relatively stable, using the thickness of the single layer of carbon fiber fabric as a reference can more accurately control the tolerance of the thickness of the comparison test block, ensuring that the comparison test block is closer to the workpiece in structure and performance, thereby improving the reliability of the test results.

[0075] As a preferred example of the present application, in S2, the delay wedge 2 is made of isotropic sound-transmitting material.

[0076] Specifically, the characteristic of isotropic materials is that the physical properties are the same in all directions. When the ultrasonic wave propagates in the delay wedge, no matter in which direction, the propagation speed and attenuation degree are relatively consistent, and the ultrasonic wave propagation path and waveform will not change due to the directional difference of the material, ensuring that the ultrasonic wave can enter the comparison test block or workpiece 3 in a stable state, thereby improving the detection accuracy.

[0077] The present application also provides a porosity ultrasonic detection device for a resin-based fiber-reinforced composite material, which is used in the aforementioned detection method, comprising:

[0078] An ultrasonic probe 1, used for transmitting ultrasonic waves to a comparison test block or a workpiece 3, and receiving ultrasonic signals 4 reflected by the comparison test block or the workpiece 3;

[0079] The delay wedge 2, the ultrasonic probe 1, the delay wedge 2 and the comparison test block are sequentially arranged in abutment from top to bottom, are well coupled with each other, and are kept vertical;

[0080] A calculation module, which establishes a relationship between the ultrasonic attenuation rate α and the porosity φ according to the ultrasonic signal 4, and obtains the attenuation rate α and the porosity φ of the workpiece 3;

[0081] A display module is used to display the output results of the calculation module and input the user's setting values;

[0082] The control module controls the working states of the calculation module and the display module according to the signal fed back by the ultrasonic probe 1 .

[0083] Specifically, the detection device is not only simple in structure and easy to operate, but also can stably propagate ultrasonic waves, reduce signal loss and interference, accurately calculate the attenuation rate and porosity, and ensure the accuracy of the detection results.

[0084] Preferably, it also includes a power module for providing power to the ultrasonic probe 1, the computing module, the display module and the control module.

[0085] Preferably, the ultrasonic probe 1 is controlled to emit an ultrasonic signal 4 , and the ultrasonic signal 4 reflected by the upper surface of the comparison test block or the workpiece 3 and the ultrasonic signal 4 reflected by the lower surface of the comparison test block or the workpiece 3 are collected.

[0086] Table 1 shows the porosity data obtained in Example 1 and the porosity data obtained by metallographic method.

[0087] Table 1:

[0088] Measurement location Ultrasonic testing porosity data (%) Porosity data verified by metallographic method (%) 1 1.22 1.26 2 1.35 1.34 3 1.26 1.28 4 0.55 0.61 5 1.82 1.85

[0089] It can be seen from Table 1 that the ultrasonic porosity detection method for resin-based fiber-reinforced composite materials described in the present application not only has accurate detection results, but is also superior to the traditional metallographic method.

[0090] In summary, the ultrasonic porosity detection device and method for resin-based fiber-reinforced composite materials described in the present application have the following advantages: 1) This method can perform regional and in-situ porosity detection on the workpiece 3, and can effectively detect the porosity of different parts of a large workpiece, thereby realizing comprehensive detection of large-scale structural fiber composite materials formed in an integrated manner; 2) It basically covers the porosity range that may appear in the actual production of resin-based fiber-reinforced composite materials, and workpieces with different porosity levels can find corresponding comparison blocks for reference detection, thereby ensuring the comprehensiveness and versatility of the detection method; 3) Setting a variety of porosities in the comparison block can enhance the reliability of the detection method.

[0091] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for ultrasonic detection of porosity of a resin-based fiber-reinforced composite material, characterized in that: Includes steps: S1: Make a comparison test block. The comparison test block and the workpiece (3) are made using the same process and materials, and then proceed to S2; S2: Testing the comparison test block, using ultrasonic probes (1) with different center frequencies to test the comparison test block respectively. Before testing, a delay wedge (2) is set on the comparison test block to adjust the propagation path and time of the ultrasonic wave. The test data is linearly fitted in sections to establish the relationship between the ultrasonic wave attenuation rate α and the porosity φ in different sections, that is, α=kf n φ m +b, enter S3; S3: Detect the workpiece (3). Use the ultrasonic probe (1) to detect the workpiece (3). According to the center frequencies X1 and X2 of the ultrasonic echo and the anisotropy coefficient of the workpiece (3), the attenuation rate is obtained. , enter S4; S4: Substitute the attenuation rate α of workpiece (3) into α=kf n φ m + b, obtain the porosity φ of the workpiece (3); Among them, f is the probe frequency, k and b are constants, and the values ​​of n, m, k, and b are determined by linear fitting. F is the anisotropy coefficient of the workpiece (3), C is the propagation speed of the ultrasonic wave in the workpiece (3), and X1 and X2 are the center frequencies of the ultrasonic echo.

2. The method for ultrasonic detection of porosity of resin-based fiber-reinforced composite materials according to claim 1, characterized in that: In S1, three different stages of comparison test blocks were made. The porosity of the comparison test blocks in the first stage was 0.5%-1.5%, the porosity of the comparison test blocks in the second stage was 1.5%-3.5%, and the porosity of the comparison test blocks in the third stage was 3.5%-5%.

3. The method for ultrasonic detection of porosity of resin-based fiber-reinforced composite materials according to claim 2, characterized in that: The comparison blocks for each stage include at least three different porosities.

4. The method for ultrasonic detection of porosity of resin-based fiber-reinforced composite materials according to claim 1, characterized in that: In S2, three ultrasonic probes (1) with different frequencies are used to detect the comparison test blocks respectively.

5. The method for ultrasonic detection of porosity of resin-based fiber-reinforced composite materials according to claim 1, characterized in that: In S2, the thickness of the delay wedge (2) is H2, , wherein V2 is the propagation velocity of the ultrasonic wave in the delay wedge (2), H3 is the thickness of the comparison test block, and V3 is the propagation velocity of the ultrasonic wave in the comparison test block.

6. The method for ultrasonic detection of porosity of resin-based fiber-reinforced composite materials according to claim 1, characterized in that: In S1, the workpiece (3) is made of a resin-based fiber-reinforced composite material, and the thickness of the workpiece (3) and the comparison test block is T, 4 mm ≥ T ≥ 2 mm.

7. The method for ultrasonic detection of porosity of resin-based fiber-reinforced composite materials according to claim 6, characterized in that: The thickness of the comparison test block is T±0.1mm.

8. The method for ultrasonic detection of porosity of resin-based fiber-reinforced composite materials according to claim 6, characterized in that: The resin ratio is ethylene resin: initiator: accelerator = 100:1.6:0.

3.

9. The method for ultrasonic detection of porosity of resin-based fiber-reinforced composite materials according to claim 1, characterized in that: In S2, the delay wedge (2) is made of isotropically acoustically transparent material.

10. An ultrasonic porosity detection device for resin-based fiber-reinforced composite materials, used in the detection method according to any one of claims 1 to 9, characterized in that: include: An ultrasonic probe (1) for transmitting ultrasonic waves to a comparison test block or a workpiece (3) and receiving ultrasonic signals (4) reflected by the comparison test block or the workpiece (3); A delay wedge (2), an ultrasonic probe (1), a delay wedge (2) and a comparison test block are arranged in abutment with each other in sequence from top to bottom; A calculation module is used to establish a relationship between an ultrasonic attenuation rate α and a porosity φ according to the ultrasonic signal (4), and obtain the attenuation rate α and the porosity φ of the workpiece (3); A display module is used to display the output results of the calculation module and input the user's setting values; The control module controls the working states of the calculation module and the display module according to the signal fed back by the ultrasonic probe (1).

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