Ultrasonic detection device for composite material radome

Abstract

The present invention relates to an ultrasonic detection device for a composite material antenna cover, which belongs to the field of non-destructive testing technology and solves the problems in the prior art such as the inability to use a single-side single probe for detection and the inability to detect longitudinal crack defects. The ultrasonic detection device for a composite material antenna cover provided by the present invention includes a probe and a multi-channel ultrasonic detector; the probe includes a first chip and a second chip that are parallel and arranged adjacent to each other at the ends; the first chip includes a delamination defect detection area and a crack defect detection area; the crack defect detection area of ​​the first chip and the second chip are respectively provided with a first wedge and a second wedge on the side close to the inspected part; the ultrasonic signal of the delamination defect detection area of ​​the first chip is used to detect the delamination defect of the inspected part, and the ultrasonic signal of the crack defect detection area of ​​the first chip and the second chip is used to detect the crack defect of the inspected part. The present invention realizes the rapid and accurate ultrasonic detection of delamination and crack defects of the composite material antenna cover by a single single-side single probe.

Description

Technical Field

[0001] The present invention relates to the technical field of non-destructive testing, and in particular to an ultrasonic testing device for a composite material antenna cover. Background Art

[0002] New composite radomes are formed using processes such as weaving and resin transfer molding, using reinforced fibers, a high-temperature resin matrix, and wave-transparent or stealthy materials. These radomes feature high porosity, high-temperature resistance, high strength, and low density. During use, these radomes are subject to high-temperature, high-velocity airflow. Internal defects can degrade mechanical properties and even cause material fracture, potentially leading to serious accidents. Therefore, effective nondestructive testing techniques are essential for verifying the internal quality of composite radomes.

[0003] Currently, ultrasonic testing is the most commonly used and effective nondestructive testing equipment for composite materials. However, the high porosity of composite radomes significantly attenuates ultrasonic signals, making them impenetrable to conventional ultrasonic testing devices. Liquid coupling agents are not tolerated on the composite surface, making conventional liquid-coupled ultrasonic testing impossible. Furthermore, composite materials are prone to delamination parallel to the layup direction and longitudinal cracks perpendicular to the layup direction. Conventional ultrasonic testing can only detect delamination defects using dual-probes on both sides, but cannot detect them using a single probe on one side, nor can they detect longitudinal cracks. Summary of the Invention

[0004] In view of the above analysis, the embodiment of the present invention aims to provide a detection device for a composite antenna cover, which can solve at least one of the following technical problems: (1) The composite antenna cover has a large porosity and greatly attenuates the ultrasonic signal. Conventional ultrasonic detection methods cannot penetrate the composite antenna cover; (2) The surface of the composite antenna cover material is not allowed to contact the liquid coupling agent, and conventional liquid-coupled ultrasonic detection cannot be used; (3) The composite antenna cover material is prone to delamination parallel to the laying direction and longitudinal cracks perpendicular to the laying direction. Conventional ultrasonic detection methods can only detect delamination defects by using double-sided dual probes, and cannot use single-sided single probe detection; (4) Conventional ultrasonic detection methods cannot detect longitudinal crack defects.

[0005] The purpose of the invention is mainly achieved through the following technical solutions:

[0006] An ultrasonic detection device for a composite material radome, comprising a probe and a multi-channel ultrasonic detector;

[0007] The probe comprises a first wafer and a second wafer which are parallel and arranged adjacent to each other at their ends;

[0008] The first wafer includes a delamination defect detection area and a crack defect detection area;

[0009] A first wedge and a second wedge are respectively provided in the crack defect detection area of ​​the first wafer and the side of the second wafer close to the test piece, and the first wedge and the second wedge are symmetrical about the interface between the first wafer and the second wafer;

[0010] The ultrasonic signal of the delamination defect detection area of ​​the first wafer is used to detect delamination defects of the inspected object, and the ultrasonic signal of the crack defect detection area of ​​the first wafer and the second wafer is used to detect crack defects of the inspected object;

[0011] The multi-channel ultrasonic detector has at least two channels of reflection and penetration working modes.

[0012] Furthermore, the ratio of the length of the delamination defect detection area and the crack defect detection area of ​​the first wafer to the length of the second wafer is 1:1:1.

[0013] Furthermore, the area of ​​the above-mentioned second chip is set as a crack defect detection area, and along the direction in which the first chip and the second chip are set parallel to each other, the ratio of the above-mentioned layered defect detection area to the sum of the lengths of the crack defect detection areas of the above-mentioned first chip and the above-mentioned second chip is 1:2.

[0014] Furthermore, the center frequency of the first chip is greater than the center frequency of the second chip.

[0015] Furthermore, the first wedge block and the second wedge block have the same structure, and the cross-section is a right triangle, the first right angle side is connected to the wedge block mounting surface of the corresponding chip; the second right angle side is perpendicular to the wedge block mounting surface of the corresponding chip; the hypotenuses of the two right triangles form a Λ shape.

[0016] Furthermore, the delamination defect detection area of ​​the first wafer emits ultrasonic waves, which propagate longitudinally to the inspected object. After being reflected by the bottom surface of the inspected object, the ultrasonic signal returns along the original path and is received by the first wafer.

[0017] Furthermore, the crack defect detection area of ​​the first chip emits ultrasonic waves, which change direction after the first wedge block and propagate laterally in the test piece. After passing through the test piece, the ultrasonic signal is received by the second chip along a symmetrical path, and the path is symmetrical about the interface between the first chip and the second chip.

[0018] Furthermore, the first wedge block and the second wedge block both satisfy the following formula:

[0019]

[0020] β+θ=α Formula 2

[0021]

[0022] Among them, C 楔块材质 is the speed of longitudinal waves in the wedge;

[0023] C 耦合剂 is the longitudinal wave velocity in the couplant;

[0024] C 兰姆波 is the Lamb wave speed in the test piece, where the Lamb wave is a transversely propagating sound wave;

[0025] θ is the angle between the propagation direction of the ultrasonic signal after it changes direction and the original propagation direction;

[0026] α is the angle between the hypotenuse of the wedge and the wedge mounting surface of the corresponding wafer;

[0027] β is the angle between the propagation direction of the ultrasonic signal after it changes direction and the vertical line of the hypotenuse of the wedge.

[0028] Furthermore, the multi-channel ultrasonic detector includes a first channel and a second channel; the first channel is set to a reflection mode, the second channel is set to a penetration mode, and the first channel and the second channel are synchronized;

[0029] The two ends of the delamination defect detection area of ​​the first wafer are respectively connected to the first channel, and the second wafer is connected to the second channel;

[0030] The delamination defect in the inspected part is detected by judging the signal of the first channel, and the crack defect in the inspected part is detected by judging the signal of the second channel.

[0031] Furthermore, the detection device further comprises a cylinder with closed ends and a cylinder rolling connection structure, the ultrasonic dry-coupling roller probe is arranged in the cylinder, and the cylinder is filled with coupling agent;

[0032] When the cylinder rolls, the first wafer and the second wafer remain stationary relative to the axial direction of the cylinder, and the cylinder and the surface of the inspected object are scanned through close rolling friction.

[0033] Furthermore, the thickness of the coupling agent layer on the DUT side of the delamination defect detection area of ​​the first wafer should meet the following requirements:

[0034]

[0035] Among them, L 耦合剂 -Thickness of the coupling agent layer, C 耦合剂 - longitudinal wave velocity of the couplant, T 被检件 -Thickness of the test piece, C 被检件 -Longitudinal wave velocity of the test piece.

[0036] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0037] 1. The present invention arranges the first chip and the second chip of the ultrasonic dry-coupled roller probe on the same side, and the first chip has an area for detecting delamination defects. The delamination defects in the composite antenna cover are detected by transmitting and receiving ultrasonic signals in this area of ​​the chip, which can realize single-side single-probe ultrasonic detection of delamination defects.

[0038] 2. The wafer of the ultrasonic dry-coupled roller probe provided by the present invention is provided with a wedge block on the side close to the inspected piece, and under the action of the wedge block, single-side single-probe detection of longitudinal crack defects can be achieved.

[0039] 3. The ultrasonic dry-coupled roller probe provided by the present invention can realize single-shot, single-side, single-probe ultrasonic detection of composite material radome delamination and crack defects through the design of the wafer and wedge.

[0040] 4. The two chips of the ultrasonic dry-coupled roller probe of the present invention have different center frequencies. The high-frequency chip can ensure high resolution when detecting delamination defects, and the low-frequency chip can ensure high sensitivity when detecting crack defects.

[0041] 5. The ultrasonic detection device provided by the present invention adopts an ultrasonic dry-coupled roller probe, and by calibrating the sensitivity of the ultrasonic instrument, it ensures the detection sensitivity of delamination and crack defects and improves the accuracy of the detection results.

[0042] 6. The present invention determines the thickness of the coupling agent to ensure that during detection, the multiple ultrasonic reflection waves of the coupling agent layer (such as the water layer) are after the reflection waves of the bottom surface of the antenna cover, so that the multiple ultrasonic reflection waves of the coupling agent layer will not affect the ultrasonic reflection signal of the antenna cover surface, further improving the accuracy of detection.

[0043] 7. The ultrasonic testing device provided by the present invention does not require any liquid coupling agent to be applied to the surface of the test piece during scanning, thus avoiding irreversible contamination of the interior of the composite material by the liquid coupling agent used in conventional ultrasonic testing.

[0044] 8. The ultrasonic detection device provided by the present invention uses an axial connecting component to enable the elastic medium of the roller probe to roll, and the elastic medium and the surface of the test piece are scanned by close rolling friction, thereby ensuring dry coupling of the ultrasonic signal. The use of rolling friction can ensure that the resistance of the probe is small when it moves during the detection process, thereby improving the detection efficiency and extending the life of the probe.

[0045] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0047] Figure 1 Schematic diagram of the detection device provided in Example 1 of the present invention;

[0048] Figure 2 A cross-sectional view of the structure of the ultrasonic dry-coupled roller probe provided in Example 1 of the present invention;

[0049] Figure 3 Schematic diagram of the relationship between the acute angle formed by the wedge and the wafer in the probe of the present invention and the direction of ultrasonic wave propagation;

[0050] Figure 4 Schematic diagram of ultrasonic detection of delamination defects according to an embodiment of the present invention;

[0051] Figure 5 Schematic diagram of ultrasonic detection of crack defects according to an embodiment of the present invention.

[0052] Reference numerals:

[0053] 1-Multi-channel ultrasonic instrument; 2-Receiving end of ultrasonic instrument channel B; 3-Transmitting end of ultrasonic instrument channel A; 4-Ultrasonic dry-coupled roller probe; 5-B interface of probe; 6-A interface of probe; 7-Connecting wire; 8-Handle; 9-Spring; 10-First wafer; 11-Second wafer; 12-First wedge; 13-Second wedge; 14-Bearing; 15-Sealing ring; 16-Shaft; 17-Wheel disc; 18-Rubber tire; 19-Thickness of the coupling agent layer on the side of the test piece in the delamination defect detection area of ​​the first wafer. DETAILED DESCRIPTION

[0054] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0055] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the term "connection" should be understood in a broad sense. For example, it can refer to a fixed connection, a detachable connection, or an integral connection. It can also refer to a mechanical connection, an electrical connection, a direct connection, or an indirect connection through an intermediate medium. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0056] The terms "surface," "bottom," "above," "below," and "on" used throughout this document refer to relative positions relative to the layered structure of the inspected portion of the radome, for example, the relative positions of the surface and bottom of the radome. It should be understood that the inspected portion of the radome is a layered structure, regardless of its orientation in space.

[0057] The working surface of the present invention can be a plane or a curved surface, can be inclined, or can be horizontal. For the convenience of description, the embodiment of the present invention is placed on a horizontal surface and used on the horizontal surface, and "high and low" and "up and down" are defined in this way.

[0058] The embodiment of the present invention provides a detection device for a composite material radome, comprising a multi-channel ultrasonic detector 1 and an ultrasonic dry-coupled ultrasonic probe 4; the wafer of the ultrasonic dry-coupled roller probe comprises a first wafer 10 and a second wafer 12 which are parallel and arranged adjacent to each other at their ends. Figure 1 、 Figure 2 shown.

[0059] The first wafer includes a delamination defect detection region and a crack defect detection region, and the length ratio of the two regions is 1:1.

[0060] A first wedge is provided on the crack defect detection area of ​​the first wafer near the inspected piece, and a second wedge is provided on the second wafer near the inspected piece; the two wedges are arranged axially symmetrically, and the axis of symmetry is the dividing line between the first wafer and the second wafer.

[0061] The ultrasonic signal of the delamination defect detection area of ​​the first wafer is used to detect the delamination defect of the inspected object, and the ultrasonic signals of the crack defect detection area of ​​the first wafer and the second wafer are used to detect the crack defect of the inspected object.

[0062] Existing roller probes usually have one or more wafers, but the wafers are all the same size, so they can only detect delamination defects, not crack defects. The present invention uses a first wafer 10 and a second wafer 11 that are parallel and arranged adjacent to each other at their ends. The first wafer 10 and the second wafer 11 have different sizes. A delamination defect detection area and a crack defect detection area are set on the first wafer 10. The ultrasonic signal of the delamination defect detection area of ​​the first wafer is used to detect delamination defects in the inspected part, and the area of ​​the second wafer is set as the crack defect detection area. The ultrasonic signals of the crack defect detection area of ​​the first wafer and the second wafer are used to detect crack defects in the inspected part.

[0063] Along the parallel direction of the first and second wafers, the ratio of the lengths of the delamination defect detection area to the crack defect detection area is 1:2. In other words, the crack defect detection area is located on both the first and second wafers, and the delamination defect detection area and part of the crack defect detection area of ​​the first wafer are located on the same wafer. This satisfies the requirement of cooperating on two wafers for defect detection and improves detection sensitivity.

[0064] In order to realize the detection of delamination defects and longitudinal crack defects on the same side (i.e., single side) and with the same probe at the same time, the wafers are arranged in parallel with the first wafer and the second wafer being arranged adjacent to each other at the ends; wherein the first wafer includes a delamination defect detection area and a crack defect detection area; wherein the crack defect detection area of ​​the first wafer and the second wafer are symmetrically provided with wedges close to the side of the inspected piece, that is, the crack defect detection area of ​​the first wafer is provided with a first wedge 12 close to the side of the inspected piece, and the crack defect detection area of ​​the second wafer is provided with a second wedge 13 close to the side of the inspected piece, and the symmetry axis of the first wedge 12 and the second wedge 13 is the dividing line between the first wafer and the second wafer.

[0065] When working, Figure 4 、 Figure 5 As shown, the delamination defect detection area of ​​the first wafer emits ultrasonic waves, which propagate longitudinally to the inspected object. After being reflected by the bottom surface of the inspected object, the ultrasonic signal returns along the original path and is received by the first wafer.

[0066] The crack defect detection area of ​​the first chip emits ultrasonic waves, which change the propagation direction after the first wedge block and enter the test piece as shear waves. After passing through the test piece, it follows a symmetrical path and passes through the second wedge block at the front end of the second chip and is received by the second chip.

[0067] When detecting crack defects, the right half of the first wafer, i.e., the crack defect detection area of ​​the first wafer, is used to transmit energy, and the crack defect detection area of ​​the second wafer, i.e., the second wafer, is used to receive energy. To ensure the same size of the transmitted and received acoustic beams, the length of the crack defect detection area of ​​the first wafer is equal to the length of the second wafer, and the size of the left half of the first wafer is equal to the size of the right half. In other words, the length of the second wafer is half the length of the first wafer.

[0068] Specifically, the length of one side of the first wedge bonded to the first wafer is equal to the length of the second wafer, and the ratio of the lengths of the first wafer delamination defect detection area, the first wafer crack defect detection area, and the second wafer crack defect detection area is 1:1:1.

[0069] To ensure the propagation path of the ultrasonic wave, it enters the test piece and turns into a shear wave, and returns to be received by the second chip. This requires the size, angle, and material of the wedge to match. The cross-section of the first wedge and the second wedge is a right triangle. The angle formed by the first right-angled side of the wedge and the wedge mounting surface of the corresponding chip is set to α. This angle α and the material of the wedge, as well as how to make the returned ultrasonic signal fall at the center of the second chip, need to satisfy the following formula relationship (such as Figure 3 shown):

[0070]

[0071] β + θ = α Formula 2

[0072]

[0073] The wedge parameters can be calculated according to formulas 1, 2, and 3; where:

[0074] C 楔块材质 is the speed of longitudinal waves in a wedge of a certain material;

[0075] C 耦合剂 is the longitudinal wave speed in a certain coupling agent;

[0076] C 兰姆波 is the Lamb wave speed in the test piece, where Lamb wave is a transversely propagating sound wave;

[0077] θ is the angle between the propagation direction of the ultrasonic signal after it changes direction and the original propagation direction;

[0078] α is the angle between the hypotenuse of the wedge and the wedge mounting surface of the corresponding wafer, that is, the first acute angle of the right triangle;

[0079] β is the angle between the propagation direction of the ultrasonic signal after it changes direction and the vertical line of the oblique side (i.e., the longest side) of the wedge.

[0080] Experimental research shows that the low density of the wedge material is conducive to the bonding of the wedge and the wafer, and the high sound velocity is conducive to distinguishing the sound velocity of the ultrasonic wave entering the test piece. Preferably, the wedge material is aluminum, which meets the characteristics of low density and high sound velocity.

[0081] For example, the wedge is made of aluminum and the coupling agent is water. The longitudinal wave velocity in aluminum is 6300 m / s, while the longitudinal wave velocity in water is 1500 m / s. The Lamb wave velocity in a composite radome is related to factors such as the ultrasonic frequency and the thickness of the composite material, making it difficult to determine its exact value. Experimental calculations show that the angle between the hypotenuse of the wedge and the wedge mounting surface of the corresponding wafer is 35-55°, or α, which is the acute angle formed by the hypotenuse of the wedge and the wafer. This ensures that the second wafer receives the returned ultrasonic signal. If the returned acoustic wave signal is positioned at the center of the second wafer, then α is preferably 40°.

[0082] The first chip and the second chip use different center frequency ranges. The first chip uses a high-frequency chip to ensure high resolution when detecting delamination defects; the second chip uses a low-frequency chip to ensure high sensitivity when detecting crack defects.

[0083] More specifically, the first chip of the dry-coupled ultrasonic probe, the first chip 10 is a high-resolution, high-energy composite material chip, has the function of transmitting and receiving ultrasonic signals, a pulse width ≤ 2 cycles, a size range of 15mm*15mm~20mm*20mm, and a center frequency range of 1MHz~5MHz; the second chip 11 is a receiving chip, which only has the function of receiving ultrasonic signals, has a side length of half the side length of the first chip, and a center frequency range of 0.25MHz~1MHz.

[0084] The multi-channel ultrasonic detector connected to the first chip and the second chip has at least two channels of the penetration method 2 and reflection method 3 working modes.

[0085] Specifically, the lower limit of the multi-channel ultrasonic instrument's receiving frequency band is no higher than 0.2MHz to ensure that the frequency range of low-frequency chips is covered by the receiving range; the transmitting voltage is no less than 400V square wave to ensure sufficient ultrasonic energy. The delamination defect detection area of ​​the first chip is connected to the ultrasonic instrument's reflection mode via a wire, and the crack defect detection area of ​​the first chip and the second chip are connected to the ultrasonic instrument's penetration mode via a wire. Channel A of the ultrasonic instrument is set to reflection mode for reflection detection of the first chip; channel B is set to penetration mode for penetration detection of the first and second chips.

[0086] In this way, the linkage between the chip, the wedge and the ultrasonic instrument channel is as follows: the first chip has the transmitting and receiving functions, and there is no wedge in the delamination defect detection area (left half) of the first chip. The chip in the delamination defect detection area (left half) of the first chip transmits ultrasonic waves, which propagate longitudinally to the test piece. After the ultrasonic signal is reflected by the bottom surface of the test piece, it returns along the original path and is received by the first chip, and is displayed on the A channel of the ultrasonic instrument; the second chip only has the receiving function, and the crack defect detection area (right half) of the first chip is bonded to the first wedge, and the front end of the second chip is bonded to the second wedge, and the two triangular wedges are axially symmetrically distributed. When the chip in the crack defect detection area (right half) of the first chip transmits ultrasonic waves, the direction is changed by the first wedge at the front end of the first chip, and it propagates horizontally in the test piece. After passing through the test piece, the ultrasonic signal returns along a symmetrical path, changes to the original propagation direction by the second wedge bonded to the second chip, is received by the second chip, and is displayed on the B channel of the ultrasonic instrument.

[0087] The amplitude is typically read directly on the ultrasonic instrument screen. The center of the probe is the center of the ultrasonic sound field, where the ultrasonic energy is highest. When the probe center coincides with the center of the defect, the energy is blocked to the greatest extent, with little or no energy reaching the bottom surface of the test piece. For example, below the contact boundary between the first and second wafers is the intersection of the two wafers' sound fields, where the ultrasonic energy is highest. When the center of this location coincides with the center of the crack defect, the energy is blocked to the greatest extent, resulting in the lowest ultrasonic signal amplitude.

[0088] Specifically, the probe detection of defects in the inspected part and the ultrasonic instrument display are linked as follows: when the probe is placed in a defect-free area, the bottom surface ultrasonic reflection signal of channel A and the ultrasonic signal amplitude of channel B are both displayed to be no less than 100%; the center of the chip in the delamination defect detection area (left half) of the probe's first chip coincides with the center position of the delamination defect, so that the amplitude of the bottom surface ultrasonic reflection signal of channel A is displayed to be no more than 20%; the contact boundary line between the first chip and the second chip coincides with the center position of the longitudinal crack defect, so that the amplitude of the ultrasonic signal of channel B is displayed to be no more than 20%.

[0089] The probe wafer of the ultrasonic dry-coupled roller probe is provided with a sealed elastic medium filled with ultrasonic coupling agent on the outside. The elastic medium ensures a consistent thickness, and during testing, the elastic medium of the probe can be pressed tightly against the surface of the sample with no gap contact. For example, the elastic medium is a rubber tire. This is because sound waves cannot effectively propagate in the air at the ultrasonic frequencies commonly used in non-destructive testing. In addition to causing signal attenuation, the acoustic impedance of air is also extremely mismatched with the anti-wear layer of the probe and the general material being tested. Even the extremely narrow air gap between the probe and the workpiece being tested will affect the effective transmission of sound energy, making conventional testing impossible.

[0090] It should be noted that elastic media, such as rubber tires, have a certain attenuation effect on ultrasonic waves, but the thickness of the rubber tires remains consistent. During detection, the ultrasonic waves attenuate uniformly when passing through the rubber tires in the propagation path, so there is no impact on the test results.

[0091] To ensure that the probe is pressed tightly against the surface of the test piece, an elastic device is installed between the upper end of the probe and the handle 8 to ensure coupling pressure, and the maximum pressure of the elastic device is ≥ 25 N. For example, the elastic device is a spring.

[0092] This allows the elastic medium and the test piece to be in contact without a gap, and the ultrasonic signal can be transmitted into the test piece, achieving a dry coupling effect.

[0093] Specifically, the ultrasonic dry-coupled roller probe achieves rolling through an axial connection, for example, the bearing 14, and the roller elastic medium and the surface of the inspected object are scanned through close rolling friction, which can ensure dry coupling of the ultrasonic signal.

[0094] The wafer axis and the wafer fixing shaft 16 are stationary and always at the nearest position to the test piece. That is, the wafer is perpendicular to the surface of the test piece along the wedge direction to ensure that the sound wave enters the test piece vertically.

[0095] Specifically, a sealing device, such as a sealing ring 15 , is provided between the axial connection component and the elastic medium to prevent the liquid coupling agent from leaking and contaminating the test piece.

[0096] More specifically, the ultrasonic dry-coupled roller probe causes the rubber tire 18 to roll through the bearing 14, and the rubber tire and the surface of the inspected object are scanned through close rolling friction.

[0097] The liquid coupling agent between the wafer and the elastic medium, such as water, has its own sound velocity. During the delamination defect detection process, within a very short distance, the ultrasonic signal passes through the coupling agent and then enters the test piece. However, there will also be some reflected signals at the boundary between the coupling agent and the test piece. If these secondary reflected signals are received by the wafer before the reflected signals from the bottom surface of the test piece, or if they are superimposed on the reflected signals from the bottom surface of the test piece, they will affect the detection signal. Therefore, the thickness of the coupling agent layer must be such that the secondary ultrasonic reflected waves of the coupling agent are behind the reflected waves from the bottom surface of the test piece and do not affect the detection signal. The ratio of the thickness of the ultrasonic coupling agent to the longitudinal wave sound velocity in the coupling agent should be greater than the ratio of the thickness of the test piece to the longitudinal wave sound velocity in the test piece. Specifically, the thickness 19 of the coupling agent layer on the test piece side of the first wafer delamination defect detection area of ​​the ultrasonic dry-coupled roller probe satisfies the formula:

[0098]

[0099] Among them, L 耦合剂 -Thickness of the coupling agent layer, C 耦合剂 - longitudinal wave velocity in the couplant, T 被检件 -Thickness of the test piece, C 被检件 -Longitudinal wave velocity in the test piece.

[0100] When in use, connect the probe's A interface 6 to the A channel transmitter 3 of the multi-channel ultrasound instrument through the connection 7, connect the probe's B interface 5 to the B channel receiver 2 through the connection 7, set the ultrasound instrument to synchronize the A channel and the B channel, and start detection.

[0101] When using the above-mentioned detection device to perform ultrasonic scanning of the composite material antenna cover, preferably, the scanning method adopts a grid type to ensure scanning efficiency; the scanning direction is consistent with the direction of the probe roller diameter to facilitate rolling advancement; the scanning step is half the length of the second chip to prevent missed detection.

[0102] The present invention provides an ultrasonic detection device for a composite material radome. The detection steps using the above detection device are as follows:

[0103] Step 1: Ensure that the material and thickness of the reference test block are identical to those of the test piece. Place two layers of polytetrafluoroethylene film inside the reference test block to simulate delamination defects, and cut grooves on the lower surface of the reference test block to simulate longitudinal crack defects.

[0104] Step 2: Set the A channel of the multi-channel ultrasound to the reflection method mode and the B channel to the penetration method mode. Connect the A interface of the probe to the A channel transmitter of the multi-channel ultrasound instrument, connect the B interface of the probe to the B channel receiver, and set the ultrasound instrument to synchronize the A channel and the B channel.

[0105] Step 3: Adjust the gain values ​​of channel A and channel B to meet the following requirements: the probe is placed in a defect-free area, the amplitudes of the bottom ultrasonic reflection signal of channel A and the ultrasonic signal of channel B are not less than 100%; the center of the left half of the first chip of the probe coincides with the center position of the artificially simulated delamination defect, so that the amplitude of the bottom ultrasonic reflection signal of channel A is not greater than 20%; the boundary line between the first chip and the second chip coincides with the center position of the artificially simulated longitudinal crack defect, so that the amplitude of the ultrasonic signal of channel B is not greater than 20%.

[0106] Step 4: Use the ultrasonic instrument and probe with determined detection sensitivity to scan the test piece. The scanning method adopts a grid type. The scanning direction is consistent with the direction of the probe roller diameter. The scanning step is the radius of the second chip of the probe.

[0107] Step 5: During scanning, when the amplitude of the ultrasonic signal of channel A is no more than 20% and is at its lowest, the location of the delamination defect is below the center of the left half of the first wafer. When the amplitude of the ultrasonic signal of channel B is no more than 20% and is at its lowest, the location of the longitudinal crack is below the boundary line between the first wafer and the second wafer.

[0108] Compared to existing technologies, the present invention's parallel placement of the first and second wafers on the same side, along with the triangular wedge, enables single-pass, single-side, single-probe ultrasonic testing of composite radome delamination and crack defects for the first time. Specifically, the triangular wedge is positioned at the front end of the crack detection area on the first wafer. The transmitted ultrasonic wave, passing through the wedge, changes its propagation direction, propagating horizontally through the test piece, thereby detecting longitudinal crack defects.

[0109] Compared with the prior art, the dual-chip center frequencies of the ultrasonic dry-coupled roller probe of the present invention are different. The high-frequency chip can ensure high resolution when detecting delamination defects, and the low-frequency chip can ensure high sensitivity when detecting crack defects.

[0110] Compared with the prior art, the present invention determines the thickness of the coupling agent to ensure that the secondary ultrasonic reflection wave of the coupling agent is after the reflection wave of the bottom surface of the antenna cover during detection, so that the secondary ultrasonic reflection wave of the coupling agent will not affect the ultrasonic reflection signal of the test object, thereby improving the accuracy of detection.

[0111] Compared with the prior art, the present invention ensures the detection sensitivity of delamination and crack defects by verifying the sensitivity of the ultrasonic instrument, thereby further improving the accuracy of the detection results.

[0112] Compared with the prior art, the ultrasonic dry-coupled roller probe of the present invention does not require any liquid coupling agent to be used on the surface of the inspected object during scanning, thereby avoiding irreversible contamination of the interior of the composite material by the coupling agent.

[0113] Example 1

[0114] This embodiment provides an ultrasonic detection device for a composite material antenna cover, such as Figure 1 、 Figure 2 The specific details of the device are as follows:

[0115] A multi-channel ultrasonic detector 1 and an ultrasonic dry-coupled roller probe 4, wherein the multi-channel ultrasonic detector has at least two channels of working modes, namely, a penetration method 2 and a reflection method 3, and the ultrasonic probe is an ultrasonic dry-coupled roller probe.

[0116] Set the A channel of the multi-channel ultrasonic instrument 1 to the reflection method mode, and the B channel to the penetration method mode. Connect the A interface 6 of the dry-coupled roller ultrasonic probe 4 to the A channel transmitting end 3 of the multi-channel ultrasonic instrument 1 via the connection 7, and connect the B interface 5 of the ultrasonic dry-coupled roller probe 4 to the B channel receiving end 2 of the ultrasonic instrument via the connection 7.

[0117] Fill the rubber tire 18 of the ultrasonic dry-coupling roller probe 4 with couplant water and remove any air bubbles. The wafer and the wafer-fixing shaft 16 remain stationary in the axial direction, and the wafer is perpendicular to the surface of the test piece along the wedge. Ensure that the wafer and wedge ensure that the sealing ring 15 is tightly connected to the wheel disc 17 and the bearing 14 to prevent water leakage.

[0118] The first chip of the dry-coupled ultrasonic probe is a high-resolution, high-energy composite material chip with transmitting and receiving functions. Model: 1-3, pulse width is 1.5 cycles, chip size is 15mm*15mm, and chip center frequency range is 2.25MHz; the second chip is a receiving chip with only receiving function. Model: PZT-5, chip size is 7.5mm*7.5mm, and center frequency range is 1MHz.

[0119] The high-frequency first chip can ensure high resolution when detecting delamination defects, and the low-frequency second chip can ensure high sensitivity when detecting crack defects.

[0120] The thickness of the coupling agent water layer at the front end of the first element of the dry-coupled roller ultrasonic probe is 10 mm, which satisfies the formula:

[0121]

[0122] Among them, L 水层 -Thickness of the water layer, C 水 - Longitudinal wave speed in water, T 被检件 -Thickness of the test piece, C 被检件 -Longitudinal wave velocity in the test piece.

[0123] The secondary ultrasonic reflection wave of the water layer can be made to be behind the reflection wave of the bottom surface of the inspected object, without affecting the detection signal.

[0124] like Figure 3 As shown, the ultrasonic dry-coupled roller probe 4 is bonded to a first aluminum wedge at the front end of the crack defect detection area (right half) of the first wafer. The triangular aluminum wedge forms a 40° angle with the first wafer 10. A second aluminum wedge is bonded to the front end of the second wafer 11, axially symmetrically distributed with the aluminum wedge at the front end of the crack defect detection area of ​​the first wafer 10. The axis of symmetry is the boundary between the first and second wafers of the probe. This ensures that the ultrasonic signal is obliquely incident on the test piece and propagates horizontally within the test piece, thereby detecting longitudinal cracks.

[0125] The transmitting voltage of the A channel and the B channel of the multi-channel ultrasound device 1 is set to 400V (square wave), the A channel and the B channel are synchronized, the receiving frequency band is set to wide band, and the lower limit of the receiving frequency band is ≤0.2MHz.

[0126] This device can detect delamination defects and / or crack defects. During delamination defect detection, the delamination defect detection area of ​​the first wafer emits ultrasonic waves, which propagate longitudinally to the test piece. After being reflected by the bottom surface of the test piece, the ultrasonic signal returns along the original path and is received by the first wafer. If the ultrasonic signal response is abnormal, it is judged that a transverse delamination defect exists inside the test piece at that location.

[0127] During crack defect detection, the crack defect detection area of ​​the first chip emits ultrasonic waves, which change the propagation direction after being changed by the first wedge and become transverse waves when entering the test piece. After passing through the test piece, the waves follow a symmetrical path and then pass through the second wedge, returning to their original propagation direction and being received by the second chip. If there is an abnormal ultrasonic signal at this time, it indicates that there is a longitudinal crack defect at this position inside the test piece.

[0128] Example 2

[0129] This embodiment provides an ultrasonic testing device for a composite radome. Using the ultrasonic testing device provided in Example 1, the test piece is an 8mm thick, high-silica fiber-reinforced phenolic resin-based composite radome. The specific steps are as follows:

[0130] Step 1: Comparison Block Processing: The comparison block is made of the same material as the test piece, with a thickness of 8mm. Two layers of polytetrafluoroethylene film are placed inside the comparison block to simulate a delamination defect, 4mm deep from the top surface, and with a size of 4mm x 4mm. A groove is cut on the bottom surface of the comparison block to simulate a longitudinal crack defect, with a depth of 4mm, a gap width of 0.5mm, and a length of 4mm.

[0131] Step 2: Probe connection and settings: Set the A channel of the multi-channel ultrasound to reflection mode and the B channel to penetration mode. Connect the A interface of the probe to the A channel transmitter of the multi-channel ultrasound instrument, connect the B interface of the probe to the B channel receiver, and set the ultrasound instrument to synchronize the A and B channels.

[0132] Step 3: Determination of detection sensitivity: Press the probe tightly to the surface of the comparison test block, and ensure the coupling pressure by the spring 9 at the upper end of the probe, the pressure is 25N, so that the rubber tire and the test piece are in seamless contact, adjust the gain values ​​of channel A and channel B, and at the same time meet the following requirements: the probe is placed in a place without artificial defects, and the ultrasonic signal amplitudes of channel A and channel B are not less than 100%; the center of the left half of the first chip coincides with the center position of the artificially simulated delamination defect, so that the amplitude of the ultrasonic reflection signal of the bottom surface of the test block of channel A is not greater than 20%; the boundary line between the first chip and the second chip of the probe coincides with the center position of the artificially simulated longitudinal crack defect, so that the amplitude of the ultrasonic signal of channel B is not greater than 20%.

[0133] Step 3: Scanning: Scan the test piece with the determined detection sensitivity. The coupling pressure is the same as that when testing the test block. Scan with a grid scanning method. The scanning direction is consistent with the direction of the probe roller diameter. The scanning step is half the diameter of the second wafer of the probe.

[0134] Step 4: Determination of defect location: During scanning, when the amplitude of the bottom surface ultrasonic reflection signal of channel A is no more than 20% and is at its lowest, the location of the delamination defect is below the center position of the left half of the first wafer. When the amplitude of the ultrasonic signal of channel B is no more than 20% and is at its lowest, the location of the longitudinal crack is below the center of the line connecting the centers of wafers A and B.

[0135] The dissection analysis of the inspected piece of Example 2 shows that the error between the actual defect position and the detected position is within 10%; delamination defects with an actual defect size of 4mm×4mm and above and crack defects with a length of 4mm and above can be quickly detected.

[0136] Example 3

[0137] This embodiment provides an ultrasonic detection device for a composite antenna cover. The ultrasonic detection device provided in Example 1 is used for detection, and the detection steps provided in Example 2 are used to perform actual detection on multiple batches of high-silica fiber reinforced phenolic resin-based composite antenna covers.

[0138] The results of Example 3 show that the detection device of the present invention can quickly detect delamination defects of 4mm×4mm or larger and cracks of 4mm or longer in the radome. Dissection and analysis of the inspected parts show that the error between the actual defect size and the detected size is within 10%.

[0139] Therefore, the detection device provided by the present invention has a detection lower limit of 4 mm.

[0140] Comparative Example

[0141] In the prior art, a water-jet coupled ultrasonic C-scan detection system uses a method of spraying water onto the surface of the radome as a coupling agent and scanning for defects inside the radome with an ultrasonic probe.

[0142] The system structure is complex and large in size. The chip design only has transmitting and receiving functions, which can detect transverse delamination defects but cannot detect longitudinal cracks and determine their locations.

[0143] The results show that the water jet coupled ultrasonic C-scan detection system in the comparative example has a detection error rate of more than 30% due to water entering the pores of the antenna cover, which interferes with the ultrasonic wave. The detection lower limit is 10mm, and defects below 10mm cannot be detected.

[0144] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. An ultrasonic detection device for a composite material radome, characterized in that: Including probe and multi-channel ultrasonic detector; The probe comprises a first wafer and a second wafer which are parallel and arranged adjacent to each other at their ends; The first wafer includes a delamination defect detection area and a crack defect detection area; A first wedge and a second wedge are respectively provided in the crack defect detection area of ​​the first wafer and the side of the second wafer close to the test piece, and the first wedge and the second wedge are symmetrical about the interface between the first wafer and the second wafer; The ultrasonic signal of the delamination defect detection area of ​​the first wafer is used to detect the delamination defect of the inspected part. The first wafer adopts a high-frequency wafer with a center frequency range of 1MHz to 5MHz. The ultrasonic signal of the crack defect detection area of ​​the first wafer and the second wafer is used to detect the crack defect of the inspected part. The second wafer adopts a low-frequency wafer with a center frequency range of 0.25MHz to 1MHz. The multi-channel ultrasonic detector has at least two channels of reflection and penetration working modes; The first wedge and the second wedge have the same structure and a right triangle cross-section, wherein the first right-angled side is connected to the wedge mounting surface of the corresponding wafer; the second right-angled side is perpendicular to the wedge mounting surface of the corresponding wafer; the hypotenuses of the two right triangles form a Λ shape; the first wedge and the second wedge both satisfy the following formula: Formula 1 Formula 2 Formula 3 Among them, C 楔块材质 is the speed of longitudinal waves in the wedge; C 耦合剂 is the longitudinal wave velocity in the couplant; C 兰姆波 is the Lamb wave speed in the test piece, where the Lamb wave is a transversely propagating sound wave; θ is the angle between the propagation direction of the ultrasonic signal after it changes direction and the original propagation direction; α is the angle between the hypotenuse of the wedge and the wedge mounting surface of the corresponding wafer; β is the angle between the propagation direction of the ultrasonic signal after it changes direction and the vertical line of the hypotenuse of the wedge.

2. The ultrasonic detection device according to claim 1, characterized in that The ratio of the length of the delamination defect detection area and the crack defect detection area of ​​the first wafer to the length of the second wafer is 1:1:

1.

3. The ultrasonic detection device according to claim 1, characterized in that The delamination defect detection area of ​​the first wafer emits ultrasonic waves, which propagate longitudinally to the inspected object. After being reflected by the bottom surface of the inspected object, the ultrasonic signal returns along the original path and is received by the first wafer.

4. The ultrasonic detection device according to claim 1, characterized in that The crack defect detection area of ​​the first chip emits ultrasonic waves, which are changed in direction by the first wedge block and propagate laterally in the test piece. After passing through the test piece, the ultrasonic signal is received by the second chip along a symmetrical path, which is symmetrical about the interface between the first chip and the second chip.

5. The ultrasonic detection device according to claim 1, characterized in that: The multi-channel ultrasonic detector includes a first channel and a second channel; the first channel is set to a reflection method mode, the second channel is set to a penetration method mode, and the first channel and the second channel are synchronized; Two ends of the delamination defect detection area of ​​the first wafer are respectively connected to the first channel, and the second wafer is connected to the second channel; The delamination defect in the inspected part is detected by judging the signal of the first channel, and the crack defect in the inspected part is detected by judging the signal of the second channel.

6. The ultrasonic detection device according to claim 1, characterized in that It also includes a cylinder with closed ends and a cylinder rolling connection structure, the probe is arranged in the cylinder, and the cylinder is filled with coupling agent; the probe is an ultrasonic dry coupling roller probe; When the cylinder rolls, the first wafer and the second wafer remain stationary relative to the axial direction of the cylinder, and the cylinder and the surface of the inspected object are scanned through close rolling friction.

7. The ultrasonic detection device according to any one of claims 1 to 6, characterized in that: The thickness of the coupling agent layer on the DUT side of the delamination defect detection area of ​​the first wafer should meet the following requirements: Among them, L 耦合剂 -Thickness of the coupling agent layer, C 耦合剂 - longitudinal wave velocity of the couplant, T 被检件 -Thickness of the test piece, C 被检件 -Longitudinal wave velocity of the test piece.

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