Ultrasonic testing method for composite parts

Abstract

The present application aims to provide a composite material part ultrasonic detection method, which comprises the following steps: preparing a plurality of angle contrast test blocks by using the same material and preparation process as the part to be detected; determining the sound attenuation caused by the corresponding inclination angle according to the plurality of angle contrast test blocks to obtain a compensation DAC correction curve; obtaining the optimal incident angle for reflection method detection, the optimal incident angle for penetration method detection and the optimal receiving angle for penetration method detection; detecting the part by using the penetration method, then detecting the part twice by using the reflection method, and adjusting the detection sensitivity according to the DAC correction curve when detecting the inclined surface. The present composite material part ultrasonic detection method can improve the accuracy of detecting parts with complex profiles and structures.

Description

Technical Field

[0001] This invention relates to the field of testing technology, and in particular to an ultrasonic testing method for composite material parts. Background Technology

[0002] Composite materials refer to two or more materials with different properties that are combined macroscopically through physical or chemical methods to form materials with new properties. Compared with traditional metallic materials, composite materials have advantages such as low density, high specific strength, impact resistance, and corrosion resistance, and have broad application prospects in aerospace and other fields. To assess the reliability of composite materials, non-destructive testing (NDT) is required for composite material parts, and ultrasonic testing is one of the most commonly used NDT methods. Ultrasonic testing is a non-destructive testing method that uses ultrasonic waves to inspect the internal structure and defects of materials.

[0003] To meet structural and aerodynamic design requirements, composite material parts used in aero engines often have complex shapes and structures, which poses many challenges to the ultrasonic testing of composite material parts. There is an urgent need to provide an ultrasonic testing method for composite material parts to achieve accurate testing of parts with complex shapes and structures. Summary of the Invention

[0004] The purpose of this invention is to provide an ultrasonic testing method for composite material parts, which can improve the accuracy of testing parts with complex shapes and structures.

[0005] An ultrasonic testing method for composite material parts, intended to achieve the aforementioned objectives, is provided for ultrasonic testing of composite material parts, wherein the parts to be tested have at least one inclined surface, and the method includes the following steps:

[0006] Multiple angle comparison test blocks are prepared using the same material and manufacturing process as the part to be tested. Each angle comparison test block has an inclined section. The upper surface of the inclined section and the bottom surface of the angle comparison test block have an inclination angle. The multiple inclination angles in the multiple angle comparison test blocks include at least the maximum value, minimum value and intermediate value of the inclination angle of the inclined surface in the part to be tested.

[0007] The acoustic attenuation caused by the corresponding tilt angle is determined based on multiple angle comparison test blocks;

[0008] The DAC curve for the vertical incidence detection method is corrected based on the sound attenuation to obtain a compensated DAC correction curve.

[0009] Obtain the optimal incident angle for reflection detection, and obtain the first DAC correction curve when the incident angle is the optimal incident angle for reflection detection; and

[0010] To obtain the optimal incident angle and the optimal receiving angle for penetration detection;

[0011] The part is inspected using a penetration method. For the inclined surface, the optimal incident angle of the penetration method is detected by the incident probe, and the optimal receiving angle of the penetration method is detected by the receiving probe and the surface of the part.

[0012] The first inspection of the part is carried out using the reflection method. The incident probe is used to detect the part with parameters perpendicular to the surface of the part, and the detection sensitivity is adjusted according to the compensation DAC correction curve.

[0013] The part is inspected a second time using the reflection method. When inspecting the inclined surface, the parameters of the optimal incident angle of the reflection method corresponding to the incident probe and the surface of the part are used for detection. At the same time, the detection sensitivity is adjusted according to the first DAC correction curve.

[0014] In one or more embodiments, each of the angle comparison test blocks further has a first parallel segment and a second parallel segment, the inclined segment connecting the first parallel segment and the second parallel segment;

[0015] The thickness of the first parallel segment is the same as the thickness of the thinnest part of the part to be tested, and the thickness of the second parallel segment is greater than the thickness of the thickest part of the part to be tested.

[0016] In one or more embodiments, determining the acoustic attenuation includes the following steps:

[0017] Place the ultrasound probe in the first parallel segment, measure the bottom echo once, adjust the echo height to 80% of the full screen height, and obtain the first gain value.

[0018] Place the ultrasonic probe at the junction of the inclined section and the first parallel section, adjust the angle of the ultrasonic probe so that the incident angle of the sound wave emitted by the ultrasonic probe is perpendicular to the inclined section, measure the bottom echo once, adjust the echo height to 80% of the full screen height, and obtain the second gain value.

[0019] The angle compensation value of the angle comparison test block is obtained by subtracting the first gain value from the second gain value. The angle compensation value reflects the sound attenuation at the corresponding tilt angle.

[0020] In one or more embodiments, the following steps are also included:

[0021] At the inclined section, the detection boundary point of the angle comparison test block is obtained. Using the detection boundary point as the boundary, the inclined section is divided into a first inclined section and a second inclined section. The first inclined section extends from the end position of the first parallel section to the detection boundary point, and the second inclined section extends from the detection boundary point to the beginning position of the second parallel section.

[0022] Specifically, a dual-probe system is used to detect the second inclined section.

[0023] In one or more embodiments, the steps for determining the detection boundary point are as follows:

[0024] Starting from the intersection of the inclined section and the first parallel section, record the bottom echo height at each interval. Adjust the echo height to 80% of the full screen height of the display screen to obtain the third gain value.

[0025] Calculate the bottom reflection distance along the direction perpendicular to the sound propagation of the slope surface;

[0026] Plot the correlation curve between the bottom reflection distance and the third gain value;

[0027] Calculate the first difference between the third gain value obtained for each of the interval distances and the first gain;

[0028] A first threshold is obtained, and the difference between the first difference and the first threshold is determined. If the first difference is greater than the first threshold, the first detection point after the first difference is greater than the first threshold is selected as the detection boundary point.

[0029] In one or more embodiments, obtaining the optimal incident angle for the reflection method detection includes the following steps:

[0030] Based on the slope angle of the part to be tested, take the corresponding angle comparison test block and invert it;

[0031] Ultrasonic waves are incident from the inverted bottom reflective horizontal plane at an angle perpendicular to the plane using an incident probe, and transmitted ultrasonic signals are received from the inclined section using a receiving probe.

[0032] Adjust the angle of the receiving probe to maximize the received signal, and obtain the angle between the ultrasonic direction and the inclined plane segment at this point as the optimal incident angle for the reflection method detection.

[0033] In one or more embodiments, obtaining the first DAC correction curve includes the following steps:

[0034] The incident angle is measured to determine the bottom reflection distance and gain value when the reflection method detects the optimal incident angle.

[0035] Plot the bottom reflection distance versus echo gain curves when the incident angle is the optimal incident angle for the reflection method detection;

[0036] When calculating the incident angle to be the optimal incident angle for the reflection method detection, this angle is compared with the angle compensation value of the test block, and then corrected according to the DAC curve of the perpendicular incident detection method based on the angle compensation value.

[0037] In one or more embodiments, obtaining the optimal incident angle and the optimal receiving angle for the penetration method detection includes the following steps:

[0038] The optimal incident angle for the penetration method detection is determined to be an angle perpendicular to the detection surface of the part;

[0039] Based on the slope angle of the part to be tested, take the corresponding angle comparison test block and invert it;

[0040] Ultrasonic waves are incident from the inverted bottom reflective horizontal plane at an angle perpendicular to the plane using an incident probe, and transmitted ultrasonic signals are received from the inclined section using a receiving probe.

[0041] Adjust the angle of the receiving probe to maximize the received signal, and record the angle between the direction of the received ultrasound and the inclined plane at this point as the optimal receiving angle for the penetration method detection.

[0042] In one or more embodiments, the part to be tested further includes a stepped structure, and the ultrasonic testing method for composite material parts further includes:

[0043] A stepped comparison test block was prepared using the same material and manufacturing process as the part to be tested.

[0044] Artificial defects are set in the stepped comparison test block.

[0045] In one or more embodiments, the ultrasonic testing method for composite material parts is used for the testing of composite material casings.

[0046] The beneficial effects of this invention are as follows:

[0047] 1) To address the shortcomings of complex-shaped composite materials having a significant impact on the acoustic attenuation of the DAC and resulting in inaccurate test results, a method for DAC correction in ultrasonic testing of composite material parts with different angles is established to improve test accuracy.

[0048] 2) To address the problem of inapplicability of detection methods and inaccurate detection results caused by changes in the angle of the detection surface, the detection boundary between single-probe and dual-probe reflection methods is determined, an optimized detection plan is formulated, step-by-step scanning is implemented, detection blind spots are eliminated, and detection reliability is improved.

[0049] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0050] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0051] Figure 1 A schematic diagram of a part to be tested according to some embodiments of this application is shown;

[0052] Figure 2 A schematic diagram of an angle comparison test block according to some embodiments of this application is shown;

[0053] Figure 3 A schematic diagram showing the transmission of sound waves in an angle comparison test block according to some embodiments of this application is shown;

[0054] Figures 4A to 4D The schematic diagram shows the principle of using the penetration method and the reflection method to inspect parts;

[0055] Figure 5 A schematic diagram is shown illustrating the method of obtaining the optimal incident angle of reflection by comparing test blocks according to some embodiments of this application;

[0056] Figure 6 A schematic diagram is shown illustrating the method of obtaining the optimal incident angle of the transmission method by comparing test blocks according to some embodiments of this application;

[0057] Figure 7 A schematic diagram of a stepped comparison test block according to some embodiments of this application is shown. Detailed Implementation

[0058] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0060] Compared to traditional metallic materials, composite materials exhibit greater attenuation and anisotropy, with significant differences between parts manufactured using different structures and processes. Traditional ultrasonic testing methods, which adjust detection sensitivity by measuring DAC curves, are limited. There is a need to develop a method for establishing DAC curves suitable for composite materials to quantitatively measure their internal defects. To establish DAC curves, it is necessary to design and prepare specialized test blocks suitable for composite materials.

[0061] The inventors discovered that traditional ultrasonic testing methods for composite material parts typically measure the DAC curve directly on a flat plate test block, without considering the influence of the anisotropy of the composite material and the angle changes of the surface on sound attenuation. Traditional composite materials use regular (e.g., flat plate) comparison test blocks, which do not consider the influence of the actual part's surface structure on sensitivity. The comparison test blocks cannot represent the test results of the actual part. Traditional testing methods use a scanning method perpendicular to the test surface. However, this testing method does not consider the influence of changes in the reflection angle and transmission angle of complex surfaces on testing parameters such as the test angle, the selection of the single test head, and the blind zone, resulting in poor testing results or even the inability to receive reflected signals.

[0062] Existing technologies include methods for determining the gradient thickness coefficient in ultrasonic testing of composite materials, used to compensate for ultrasonic testing signals of composite structures with varying thicknesses. These methods consider the alteration of incident sound wave propagation behavior within the composite material due to its varying thickness, and compensate the testing system based on the gradient thickness coefficient, thereby improving testing accuracy. However, these methods do not consider the impact of structural changes, such as variations in ultrasonic reflection and transmission angles at corners, on the testing process. They also do not account for the reliability issues caused by blind zones in the testing method, and do not optimize the testing scheme to address the limitations of blind zones and reflection methods.

[0063] After research, the applicant found that due to the complex surface of composite materials, the changes in reflection and transmission angles have a significant impact on the inspection. Conventional perpendicular incidence inspection methods are no longer applicable. It is necessary to establish an inspection scheme suitable for complex structural parts and determine the optimal inspection angle to improve the accuracy of the inspection results.

[0064] To overcome the shortcomings of traditional ultrasonic testing methods for composite materials: 1) the acoustic attenuation of complex-shaped composite materials significantly affects the DAC (Acoustic Density Diameter), leading to inaccurate test results; 2) the lack of suitable comparison test blocks for ultrasonic testing of complex-shaped composite materials; and 3) the inapplicability of conventional single-method testing to the scanning of the entire part due to the complex shape, even resulting in blind spots, this application provides an ultrasonic testing method for composite material parts, which is used for testing such... Figure 1 The composite material part 9 shown is subjected to ultrasonic testing, wherein the composite material part 9 has at least one inclined surface 90, of course, as Figure 1 The composite material part 9 shown has two bevels 90, which is only an example. It is understood that this ultrasonic testing method for composite material parts is applicable to ultrasonic testing of other configurations of composite material parts with at least one bevel.

[0065] The ultrasonic testing method for composite material parts includes the following steps:

[0066] Multiple angle comparison test blocks were prepared using the same materials and manufacturing processes as the parts to be tested, such as... Figure 2 A perspective view of one embodiment of the angle comparison test block is shown. Each angle comparison test block 1 has a first parallel segment 11, a second parallel segment 12, and an inclined segment 13 connecting the first parallel segment 11 and the second parallel segment 12. The upper surfaces of the first parallel segment 11 and the second parallel segment 12 are parallel to the bottom surface 14 of the angle comparison test block. The upper surface of the inclined segment 13 has an angle θ with the bottom surface 14 of the angle comparison test block. The multiple angles in the multiple angle comparison test blocks 1 include at least the maximum value, minimum value, and intermediate value of the angle of inclination of the inclined surface in the part to be tested. That is, the multiple inclined segments 13 of the multiple angle comparison test blocks 1 each have a corresponding angle θ, and the multiple angles θ include the maximum value, minimum value, and intermediate value of the angle of inclination of the inclined surface in the part to be tested 9. The thickness of the first parallel segment 11 is the same as the thickness of the thinnest part in the part to be tested 9, and the thickness of the second parallel segment 12 is greater than the thickness of the thickest part in the part to be tested 9. Figure 1 As shown in the example, the thickness of the first parallel segment 11 is the same as the thickness of the thinnest part of the part to be tested 9, that is, the thickness of the parts on both sides of the two inclined surfaces 90. The thickness of the second parallel segment 12 is greater than the thickness of the thickest part of the part to be tested 9, that is, the thickness of the part between the two inclined surfaces 90 of the part.

[0067] Subsequently, the acoustic attenuation caused by the tilt angle θ corresponding to each angle of the test block 1 was determined by comparing test block 1 from multiple angles.

[0068] In one specific embodiment, the steps for determining sound attenuation are as follows:

[0069] Place the ultrasonic probe on the first parallel segment 11 of the angle comparison test block 1, measure the bottom echo once, adjust the echo height to 80% of the full screen height, and obtain the first gain value ΔH0.

[0070] Place the ultrasonic probe at the junction of the inclined section 13 and the first parallel section 11 of the angle comparison test block 1. Adjust the angle of the ultrasonic probe so that the incident angle of the sound wave emitted by the ultrasonic probe is perpendicular to the inclined section 13. Measure the bottom echo once and adjust the echo height to 80% of the full screen height to obtain the second gain value ΔH1.

[0071] Subtracting the first gain value ΔH0 from the second gain value ΔH1 yields the angle compensation value ΔB for the corresponding angle comparison test block 1. θ0 The compensation value ΔB is obtained through this angle. θ0 The acoustic attenuation caused by the corresponding tilt angle θ.

[0072] Subsequently, optionally, the detection boundary point of the angle comparison test block is obtained at the inclined section 13. Using the detection boundary point as the boundary, the inclined section 13 is divided into a first inclined section and a second inclined section. The first inclined section extends from the end position of the first parallel section to the detection boundary point, and the second inclined section extends from the detection boundary point to the beginning position of the second parallel section. Figure 2 Taking the comparison test block shown as an example, the detection boundary point 10 of the angle comparison test block 1 is obtained. The detection boundary point 10 divides the angle comparison test block 1 into the first inclined section 15 and the second inclined section 16.

[0073] In a specific embodiment, the steps for determining the detection boundary point 10 are as follows:

[0074] Starting from the junction of the inclined section 13 and the first parallel section 11 of the angle comparison test block 1, the bottom echo height is recorded at every interval Δd. The echo height is adjusted to 80% of the full screen height of the display screen to obtain the third gain value ΔH. j .

[0075] Calculate the top reflection distance d along the direction perpendicular to the sound propagation of the slope surface. j Wherein, the propagation distance corresponding to the detection positions separated by (j-1)Δd is d. j .

[0076] Subsequently, the bottom reflection distance d is plotted. j With the third gain value ΔH j The correlation curve is denoted as d. j -ΔH j curve.

[0077] by Figure 3Taking the example shown, where the propagation path of the sound wave inside the material at the starting position of the slope is marked as d1, and the upper surface of the inclined section 13 has an angle θ with the bottom surface 14 of the angle comparison test block, then:

[0078] d1 = d0 / cosθ; d j =d0 / cosθ+(j-1)Δd×tanθ.

[0079] Subsequently, the third gain value ΔH is calculated for each interval distance Δd. j The first difference ΔB between the first gain ΔH0 measured with the parallel segment and the first gain ΔH0 is... θj .

[0080] Obtain the first threshold and determine the first difference ΔB. θj The size between the first threshold and the first difference ΔB θj If the sound attenuation exceeds the first threshold, it is considered that the sound attenuation caused by the angle and detection distance exceeds the detection range of a single probe. In this case, the first difference ΔB is selected. θj The first detection point after exceeding the first threshold is the detection boundary point 10.

[0081] In one specific embodiment, the value of the first threshold is an empirical value obtained through multiple trials, for example, 6dB, that is, when ΔB θj If the attenuation is greater than 6 dB, it is considered that the acoustic attenuation caused by the angle and detection distance exceeds the detection range of a single probe. ΔB θj The first detection point with a value greater than or equal to 6 dB is considered the detection limit of the single-probe reflection method.

[0082] Subsequently, based on the angle compensation value ΔB θ0 The DAC curve of the vertical incidence detection method is corrected. For example, firstly, the incident probe is made perpendicular to the surface of the part, that is, perpendicular to the first parallel segment 11, the second parallel segment 12, and the inclined segment 13 respectively, to obtain the basic DAC curve for the part. Then, for the detected defect that is deeply buried below the sound wave propagation path d1 inside the material at the beginning of the slope, that is, at each point of the DAC curve at the first parallel segment 11, the angle compensation value of the angle test block, i.e., ΔB, is directly added. θ The detected defect is located deep within the slope at the beginning of the slope, above the sound wave propagation path d1 within the material, specifically at each point on the DAC curve corresponding to d1 in the slope section 13 and the second parallel section 12. j The value is added sequentially to the third gain value ΔH j The difference between the gain value ΔH1 at the starting position of inclined section 13 and the gain value ΔH j -ΔH1). Complete the correction of the entire DAC curve to obtain the compensated DAC correction curve: DAC-0.

[0083] Based on the propagation direction of the ultrasonic waves within the part, a detection blind zone can be determined in angle comparison test block 1. Figure 3 As shown in the example, due to the angle between the detection surface and the bottom reflective surface, there are triangular blind zones at the bottom and top of the slope caused by the angle θ. The angle comparison test block 1 has a first detection blind zone 20a and a second detection blind zone 20b.

[0084] Subsequently, this detection method will employ both reflection and transmission methods for detection. It is understandable that both the reflection and transmission methods have their own limitations. Figure 3 The detection blind zone is shown.

[0085] To better understand this invention, the detection methods of reflection and penetration are described in detail below.

[0086] Regarding the reflection method: such as Figure 4A As shown, defect 100a exists in angle comparison test block 1a, with an angle θa between its inclined section and the bottom surface. The incident probe is inserted at an angle perpendicular to the inclined section, and the incident path is I. 0a The refraction path after detecting defect 100a is R. 1a The probe collects and detects the incident and refracted ultrasonic waves. Because there is an angle θa between the incident surface and the defect plane, when the wave is incident perpendicularly, the reflected wave will deviate from the incident point, resulting in a deflection angle δa. For example... Figure 4B As shown, a defect 100b exists in the angle comparison test block 1b, with its inclined section forming an angle θb with the bottom surface. Due to the excessive depth of defect 100b, the incident path is I. 0b Refraction path R after detecting defect 100b 1b The distance between them exceeds the detection range of a single probe, therefore, as mentioned earlier, it is necessary to obtain the detection boundary point. Figure 4C As shown, a defect 100c exists in the angle comparison test block 1c, with an angle θc between its inclined section and the bottom surface. To maximize the reflected echo from the defect and ensure its detection by the probe, the optimal method is to ensure that the incident wave, after being transmitted through the detection surface, travels to the defect perpendicular to its extension direction and is reflected back perpendicular to the defect's extension direction in the opposite direction of the incident direction, ultimately being received by the probe. Figure 4C As shown, when the incident probe has an incident path of I... 0c That is, the angle between it and the inclined plane segment is θ 0c When incident at an angle θ, the incident wave can propagate to defect 100c perpendicular to the defect extension direction. The incident angle θ at this time... 0c This is the optimal angle of incidence.

[0087] Regarding the penetration method: For composite materials, in addition to the reflection method, the impact of thickness and acoustic attenuation on detection sensitivity should also be considered. For composite materials with large thickness and high acoustic attenuation, the penetration method is selected for detection. Then, for defects detected by the penetration method, the nature and size of the defects are quantitatively assessed using reflection ultrasonic testing. Figure 4D As shown, for angle comparison test block 1d, the incident path is I. 0d The incident path is I 0d The ultrasonic wave is incident at an angle perpendicular to the inclined plane. After penetrating the part, it exits along an exit path T. 1d Transmission occurs when the angle between the inclined plane and the base is θd, resulting in the emission path T. 1d There is an angle βd between the probe and the bottom surface of the part. The two probes are located on either side of the angle comparison block 1d, with the receiving probe receiving the signal along the exit path T. 1d The received signal is maximized when the angle of the receiving probe is adjusted to be along the propagation direction of the transmitted sound wave; this is the optimal receiving angle.

[0088] Based on the aforementioned reflection and penetration methods for detection, this ultrasonic testing method for composite material parts further includes the following steps:

[0089] To obtain the optimal incident angle for reflection detection;

[0090] Obtain the first DAC correction curve when the incident angle is the optimal incident angle for reflection method detection; and

[0091] To obtain the optimal incident angle and the optimal receiving angle for penetration detection.

[0092] In one specific embodiment, determining the optimal incident angle for reflection detection includes the following steps:

[0093] Based on the angle of the inclined surface of the part to be tested, take the corresponding angle comparison test block 1e, invert it so that the bottom reflective surface faces upward, and place it horizontally, as shown. Figure 5 As shown.

[0094] Two ultrasonic probes are used: an incident probe 31 for emitting ultrasonic waves and a receiving probe 32 for receiving ultrasonic waves.

[0095] Ultrasonic waves are incident from the inverted bottom reflective horizontal plane 10e using an incident probe 31 at an angle perpendicular to the plane, and transmitted ultrasonic signals are received from the lower inclined section 13e using a receiving probe 32.

[0096] Subsequently, the angle of the receiving probe 32 is adjusted to maximize the received signal. At this point, the angle between the direction of the received ultrasound by the receiving probe 32 and the inclined section 13e is the transmission angle βe of the transmitted wave from the bottom surface. This angle value is recorded. According to the principle of reversible acoustic loops, this angle βe is the incident angle at which the transmitted wave is perpendicularly transmitted from the bottom reflecting surface when incident from the inclined surface at this angle. This angle βe is the optimal incident angle for detection using the optimal reflection method.

[0097] Furthermore, in a specific embodiment, obtaining the first DAC correction curve when the incident angle is the optimal incident angle for reflection method detection includes the following steps:

[0098] First, measure the bottom reflection distance d when the incident angle is the optimal incident angle βe for the reflection method. j and the gain value ΔH j For example, if the measurement is performed using the same method as described above, and the thickness of the first parallel segment 11 is denoted as d0, then the bottom reflection distance d j Calculate using the following formula:

[0099] d1 = d0; d j =d0+(j-1)Δd×sinβe.

[0100] Subsequently, the bottom reflection distance d is plotted when the incident angle is the optimal incident angle for the reflection method. j With echo gain ΔH j Curve (d) j -ΔH j curve).

[0101] Subsequently, when the incident angle is the optimal incident angle βe for the reflection method detection, the angle compensation value ΔB of this angle is compared with that of the test block. θβe For example, the angle compensation value ΔB can be calculated as described above. θ0 The same method was used to calculate it, so it will not be repeated here.

[0102] Subsequently, the gain ΔH at each measurement point on the inclined plane section was calculated when the incident angle was βe, which was the optimal incident angle for the reflection method. j The difference between the gain ΔH0 measured on the parallel segment and the gain ΔB is denoted as ΔB. θj .

[0103] Subsequently, based on the angle compensation value ΔB θβeThe DAC curve of the vertical incidence detection method is corrected. For example, firstly, the incident probe is made perpendicular to the surface of the part, that is, perpendicular to the first parallel segment 11, the second parallel segment 12, and the inclined segment 13 respectively, to obtain the basic DAC curve for the part. Then, for the detected defect that is deeply buried below the sound wave propagation path d1 inside the material at the beginning of the slope, that is, at each point of the DAC curve at the first parallel segment 11, the angle compensation value of the angle test block, i.e., ΔB, is directly added. θβe The detected defect is located deep within the slope at the beginning of the slope, above the sound wave propagation path d1 within the material, specifically at each point on the DAC curve corresponding to d1 in the slope section 13 and the second parallel section 12. j The value is added sequentially to the third gain value ΔH j The difference between the gain value ΔH1 at the starting position of inclined section 13 and the gain value ΔH j -ΔH1). Complete the correction of the entire DAC curve to obtain the first DAC correction curve: DAC-β.

[0104] In a specific embodiment, obtaining the optimal incident angle and the optimal receiving angle for penetration detection includes the following steps:

[0105] First, determine the optimal incident angle, selecting an angle perpendicular to the detection surface. Since the incident sound wave energy is emitted, the received reflected signal is reduced; therefore, to minimize signal attenuation, the optimal incident angle should be perpendicular to the detection surface. After determining the incident angle, the method for determining the receiving angle is as follows:

[0106] Based on the angle of the inclined surface of the part to be tested, take the corresponding angle comparison test block 1f, invert it so that the bottom reflective surface faces upward, and place it horizontally. Figure 6 As shown.

[0107] Two ultrasonic probes are used: an incident probe 31 for emitting ultrasonic waves and a receiving probe 32 for receiving ultrasonic waves.

[0108] Ultrasonic waves are incident from the inverted bottom reflective horizontal plane 10f using an incident probe 31 at an angle perpendicular to the plane, and transmitted ultrasonic signals are received from the lower inclined section 13f using a receiving probe 32.

[0109] Subsequently, the angle of the receiving probe 32 is adjusted to maximize the received signal. At this point, the angle between the direction of the received ultrasound by the receiving probe 32 and the inclined section 13f is the transmission angle βf of the transmitted wave from the bottom surface. Record this angle value.

[0110] Finally, the optimal incident angle for the penetration method detection was determined to be the angle between the incident sound wave and the detection surface when the probe is perpendicular to the detection surface, and the transmission angle βf was determined to be the optimal receiving angle for the penetration method detection.

[0111] After obtaining specific testing parameters through angle comparison test blocks, this ultrasonic testing method for composite material parts further includes the following steps:

[0112] The part is inspected using the penetration method. When inspecting parallel sections, the parameters are measured with the incident probe and the receiving probe perpendicular to the part surface. When inspecting inclined sections, the incident probe is placed at the optimal incident angle for the penetration method, which is obtained by comparing the angle of the incident probe with the angle of the inclined plane. The receiving probe is placed at the optimal receiving angle for the penetration method, which is measured with the part surface. Specifically, the optimal incident angle for the penetration method is when the incident probe is perpendicular to the part surface.

[0113] It is understandable that the phrase "the probe is perpendicular to the part or forms an angle with the part surface" as mentioned in the text refers to the ultrasonic wave path emitted or received by the probe being perpendicular to or forming an angle with the part surface.

[0114] Subsequently, the part is inspected for the first time using the reflection method. During this first inspection, the incident probe is used with parameters perpendicular to the surface of the part, and the detection sensitivity is adjusted according to the compensation DAC correction curve: DAC-0.

[0115] Subsequently, the part is inspected a second time using the reflection method. During this second inspection, when inspecting the parallel section, the parameter is that the incident probe is perpendicular to the surface of the part; when inspecting the inclined section, the parameter is that the incident probe and the surface of the part are in the optimal incident angle using the reflection method. At the same time, the detection sensitivity is adjusted according to the first DAC correction curve: DAC-β.

[0116] When using the reflection method to inspect parts, if the part thickness exceeds the detection range of a single probe, the area below the detection boundary point 10 is inspected using the single-probe ultrasonic reflection method, while the area above the detection boundary point 10 is inspected using the dual-probe ultrasonic reflection method with one transmitter and one receiver. Specifically, taking the inspection of a calibration comparison block as an example, during the first round of inspection using the reflection method, the first parallel section 11, the first inclined section 15, and the second parallel section 12 are ultrasonically inspected using the single-probe pulse reflection method, while the second inclined section 16 is ultrasonically inspected using the dual-probe pulse reflection method. During the ultrasonic inspection of the second inclined section 16, the incident probe is used with parameters perpendicular to the part surface, and the angle between the reflecting probe and the part surface is calculated based on the sound wave propagation path within the part. During the second round of inspection using the reflection method, the inclined section 13 is inspected using the single-probe pulse reflection method.

[0117] The detection method described above has the following advantages:

[0118] 1) To address the shortcomings of complex-shaped composite materials having a significant impact on the acoustic attenuation of the DAC and resulting in inaccurate test results, a method for DAC correction in ultrasonic testing of composite material parts with different angles is established to improve test accuracy.

[0119] 2) To address the problem of inapplicability of detection methods and inaccurate detection results caused by changes in the angle of the detection surface, the detection boundary between single-probe and dual-probe reflection methods is determined, an optimized detection plan is formulated, step-by-step scanning is implemented, detection blind spots are eliminated, and detection reliability is improved.

[0120] In one embodiment, the ultrasonic testing method for composite material parts further includes a stepped structure for the part 9 to be tested. The ultrasonic testing method for composite material parts also includes:

[0121] A stepped comparison test block was prepared using the same material and manufacturing process as the part to be tested, such as... Figure 7 As shown, the stepped comparison test block 6 includes multiple thicknesses, which include at least the maximum, minimum and intermediate thicknesses of the tested parts.

[0122] Artificial defect 61 is set in the stepped comparison test block, and the size of artificial defect 61 is determined according to the testing requirements.

[0123] The embedment depths of artificial defects 61 are defined as near-surface resolution, intermediate thickness, and far-surface resolution. For plywood materials, the embedment depths of artificial defects 61 are typically set between the first and second layers, in the intermediate layer, and between the penultimate and second layers.

[0124] By using a stepped comparison test block, the detection parameters of the stepped structure part of the corresponding component can be obtained.

[0125] The ultrasonic testing method for composite material parts is illustrated below, taking the part to be tested, 9, as a fiber-laid resin-based composite material casing as an example.

[0126] First, stepped comparison test blocks of different thicknesses were prepared. These test blocks included different thickness ranges (35mm, 25mm, 20mm, 22.5mm, 15mm, 10mm, 5mm), and the included thicknesses at least included the largest (35mm), smallest (10mm), and intermediate (22.5mm) thickness values ​​of the part under test. Furthermore, to obtain more DAC data, thicknesses of 30mm, 25mm, 20mm, 15mm, and 5mm were added in this example.

[0127] The size of the artificial defects in the test blocks is determined according to the testing requirements. In this example, it is required to detect defects with a diameter of 6mm. Therefore, the test blocks are designed with artificial defects with diameters of 3mm and 6mm.

[0128] The artificial defect embedment depths are defined as near-surface resolution, intermediate thickness, and far-surface resolution. For layered composite materials, the artificial defect embedment depths are typically set between the first and second layers, the intermediate layer, and between the penultimate and second layers.

[0129] Subsequently, angle comparison test blocks were prepared. The comparison test blocks were prepared using the same material and process as the composite material parts under test. The comparison test blocks included different angle ranges (30°, 25°, 20°, 15°, 10°, 5°), and the included angles at least included the maximum (30°), minimum (10°), and intermediate (20°) angle values ​​of the parts under test.

[0130] The echo amplitude was measured on artificial defects at different burial depths on a stepped test block with a flat surface. The gain of the echo amplitude at 80% of the full screen height was recorded, and the gain value was recorded. The corresponding amplitudes or gains of artificial defects with the same aperture but different burial depths were plotted as defect burial depth-echo amplitude (gain) curves, i.e., DAC curves, denoted as "DAC-foundation".

[0131] Place the probe at the starting position of the thin section on the inclined surface of the angled test block, and adjust the probe angle so that the probe is perpendicular to the inclined surface. At this time, adjust the height of the first bottom echo to 80% of the full screen height, and record the gain value ΔH1 at this time.

[0132] The gain value obtained from the first parallel segment, ΔH1-ΔH0, is used to obtain the angle compensation value of the test block at that angle, ΔB. θ0 The thickness of the parallel section in the thin area is denoted as d0 = 10 mm. The angle compensation value ΔB is... θ0 This reflects the sound attenuation caused by the angle between the detection surface and the bottom reflecting surface.

[0133] Starting from the bottom of the slope, the detection is carried out along the bottom of the slope section towards the top, and the bottom echo height Hj is recorded at every distance dd2mm.

[0134] The optimal incident angle for ultrasonic testing of composite material parts was obtained by the reflection method. Specifically, for the two inclined sections of the part to be tested 9, the optimal incident angles for the reflection method were 5° and 14.5°, respectively.

[0135] Subsequently, the DAC correction values ​​were calculated for incident angles of 5° and 14.5°, and the corrected DAC curves were plotted.

[0136] The optimal incident and receiving angles for the penetration method were determined using this ultrasonic testing method for composite material parts. The optimal incident angle should be perpendicular to the testing surface. For the two inclined sections of the part 9 to be tested, the optimal receiving angles for the penetration method are 5° and 14.5°, respectively.

[0137] By comparing the angles of the test blocks, the inspection plan for part 9 is as follows:

[0138] Perform penetration testing. The part is inspected in segments, including parallel sections and inclined sections. Specific scanning parameter settings are as follows:

[0139]

[0140] The parameters for the first reflection method detection are as follows:

[0141]

[0142] For the second reflection method detection, the optimal incident angle β was used, and the detection sensitivity was adjusted according to the first DAC correction curve: DAC-β. The detection parameters are as follows:

[0143]

[0144] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0145] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for ultrasonic testing of composite material parts, used to perform ultrasonic testing on composite material parts, wherein the part to be tested has at least one inclined surface, characterized in that, The method includes the following steps: Multiple angle comparison test blocks are prepared using the same material and manufacturing process as the part to be tested. Each angle comparison test block has an inclined section. The upper surface of the inclined section and the bottom surface of the angle comparison test block have an inclination angle. The multiple inclination angles in the multiple angle comparison test blocks include at least the maximum value, minimum value and intermediate value of the inclination angle of the inclined surface in the part to be tested. The acoustic attenuation caused by the corresponding tilt angle is determined based on multiple angle comparison test blocks; The DAC curve for the vertical incidence detection method is corrected based on the sound attenuation to obtain a compensated DAC correction curve. Obtaining the optimal incident angle for reflection detection includes the following steps: Based on the slope angle of the part to be tested, take the corresponding angle comparison test block and invert it; Ultrasonic waves are incident from the inverted bottom reflective horizontal plane at an angle perpendicular to the plane using an incident probe, and transmitted ultrasonic signals are received from the inclined section using a receiving probe. Adjust the angle of the receiving probe to maximize the received signal, and obtain the angle between the ultrasonic direction and the inclined section at this time as the optimal incident angle for the reflection method detection; And obtain the first DAC correction curve when the incident angle is the optimal incident angle for the reflection method detection; Obtaining the optimal incident angle and the optimal receiving angle for penetration detection includes the following steps: The optimal incident angle for the penetration method detection is determined to be an angle perpendicular to the detection surface of the part; Based on the slope angle of the part to be tested, take the corresponding angle comparison test block and invert it; Ultrasonic waves are incident from the inverted bottom reflective horizontal plane at an angle perpendicular to the plane using an incident probe, and transmitted ultrasonic signals are received from the inclined section using a receiving probe. Adjust the angle of the receiving probe to maximize the received signal, and record the angle between the direction of the received ultrasound and the inclined plane section at this time as the optimal receiving angle for the penetration method detection. The part is inspected using a penetration method. For the inclined surface, the optimal incident angle of the penetration method is detected by the incident probe, and the optimal receiving angle of the penetration method is detected by the receiving probe and the surface of the part. The first inspection of the part is carried out using the reflection method. The incident probe is used to detect the part with parameters perpendicular to the surface of the part, and the detection sensitivity is adjusted according to the compensation DAC correction curve. The part is inspected a second time using the reflection method. When inspecting the inclined surface, the parameters of the optimal incident angle of the reflection method corresponding to the incident probe and the surface of the part are used for detection. At the same time, the detection sensitivity is adjusted according to the first DAC correction curve.

2. The ultrasonic testing method for composite material parts as described in claim 1, characterized in that, Each of the angle comparison test blocks also has a first parallel segment and a second parallel segment, and the inclined segment connects the first parallel segment and the second parallel segment; The thickness of the first parallel segment is the same as the thickness of the thinnest part of the part to be tested, and the thickness of the second parallel segment is greater than the thickness of the thickest part of the part to be tested.

3. The ultrasonic testing method for composite material parts as described in claim 2, characterized in that, Determining the sound attenuation includes the following steps: Place the ultrasound probe in the first parallel segment, measure the bottom echo once, adjust the echo height to 80% of the full screen height, and obtain the first gain value. Place the ultrasonic probe at the junction of the inclined section and the first parallel section, adjust the angle of the ultrasonic probe so that the incident angle of the sound wave emitted by the ultrasonic probe is perpendicular to the inclined section, measure the bottom echo once, adjust the echo height to 80% of the full screen height, and obtain the second gain value. The angle compensation value of the angle comparison test block is obtained by subtracting the first gain value from the second gain value. The angle compensation value reflects the sound attenuation at the corresponding tilt angle.

4. The ultrasonic testing method for composite material parts as described in claim 3, characterized in that, It also includes the following steps: At the inclined section, the detection boundary point of the angle comparison test block is obtained. Using the detection boundary point as the boundary, the inclined section is divided into a first inclined section and a second inclined section. The first inclined section extends from the end position of the first parallel section to the detection boundary point, and the second inclined section extends from the detection boundary point to the beginning position of the second parallel section. Specifically, a dual-probe system is used to detect the second inclined section.

5. The ultrasonic testing method for composite material parts as described in claim 4, characterized in that, The steps for determining the detection boundary point are as follows: Starting from the intersection of the inclined section and the first parallel section, record the bottom echo height at each interval. Adjust the echo height to 80% of the full screen height of the display screen to obtain the third gain value. Calculate the bottom reflection distance along the direction perpendicular to the sound propagation of the slope surface; Plot the correlation curve between the bottom reflection distance and the third gain value; Calculate the first difference between the third gain value obtained for each of the interval distances and the first gain; A first threshold is obtained, and the difference between the first difference and the first threshold is determined. If the first difference is greater than the first threshold, the first detection point after the first difference is greater than the first threshold is selected as the detection boundary point.

6. The ultrasonic testing method for composite material parts as described in claim 1, characterized in that, Obtaining the first DAC correction curve includes the following steps: The incident angle is measured to determine the bottom reflection distance and gain value when the reflection method detects the optimal incident angle. Plot the bottom reflection distance versus echo gain curves when the incident angle is the optimal incident angle for the reflection method detection; When calculating the incident angle to be the optimal incident angle for the reflection method detection, this angle is compared with the angle compensation value of the test block, and the DAC curve of the vertical incident detection method is corrected according to the angle compensation value.

7. The ultrasonic testing method for composite material parts as described in claim 1, characterized in that, The part to be tested also includes a stepped structure, and the ultrasonic testing method for the composite material part further includes: A stepped comparison test block was prepared using the same material and manufacturing process as the part to be tested. Artificial defects are set in the stepped comparison test block.

8. The ultrasonic testing method for composite material parts as described in claim 1, characterized in that, The ultrasonic testing method for composite material parts is used for the testing of composite material casings.

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