Ultrasonic testing method for composite tapered cylinder

Abstract

The present invention discloses a method for ultrasonic testing of composite material conical cylinders. First, the composite material conical cylinder to be tested is placed with its opening facing upwards and filled with water. The internal and external ultrasonic probes and probe arms are parallel to the busbar direction of the tested part, driving the internal and external probes to scan synchronously through an ultrasonic C-scanning device, respectively obtaining an image A showing the internal stratification of the tested part and an image B showing all defects inside the tested part. The RGB value of each coordinate point in image A is then converted to 225-RGB to obtain image C. The RGB value of each position in image B is added to the RGB value of the corresponding position in image C to obtain an image D showing the internal loose defects of the tested part. Finally, the original ultrasonic C-scan image is subjected to geometric correction to obtain an ultrasonic C-scan image that is consistent with the actual unfolded image of the tested part. The method of the present invention solves the problem that existing ultrasonic testing cannot detect the internal stratification and loose defects of composite material conical cylinders in a one-time, rapid, accurate, and highly sensitive manner.

Description

Technical Field

[0001] The invention relates to an ultrasonic detection method for a composite material conical cylinder, and belongs to the field of ultrasonic non-destructive detection. Background Art

[0002] Composite cones are widely used in spacecraft nose components, such as radomes and heat shields. Because these components are subject to significant aerodynamic, thermal, and vibration loads during flight, internal defects can significantly impact product quality. In severe cases, they can lead to failure or fracture during flight, potentially causing a major flight accident. To ensure the safety and reliability of these composite cones and prevent potential accidents, effective nondestructive testing techniques are essential for internal quality assurance.

[0003] Composite conical tubes have a wall thickness of 1mm to 10mm, an outer diameter of 30mm to 400mm at the large end, and a closed tip at the small end. Because this structure is a new composite material, it exhibits high attenuation, large variations in tube wall thickness, a closed small end, and requires high detection sensitivity. Few nondestructive testing cases for this type of structure exist domestically or internationally.

[0004] A review revealed few relevant patents and papers. CN 115219593 A, "Air-coupled ultrasonic testing system and method for composite cylindrical parts," describes a method for testing small-diameter fiber-wound shell composite cylindrical parts using an air-coupled ultrasonic testing system. However, this method is only applicable to open composite cylindrical parts with a circular shape, not conical ones. Furthermore, it can only determine the horizontal position of defects, not their depth or nature, making it inapplicable to the composite conical cylinders described in the present invention.

[0005] CN 211478172 U "Phase-controlled array ultrasonic detection system for detecting defects in carbon fiber cylindrical structural components" describes an ultrasonic detection method for debonding defects in the carbon fiber and metal bonding layers of carbon fiber composite cylindrical structural components. However, this method is only applicable to open composite cylinders with a circular shape and cannot be applied to the detection of conical cylinders. Furthermore, the method only detects defects in the bonding between the composite material and the metal and does not describe a method for detecting defects within the composite material. Therefore, the method cannot be applied to the composite conical cylinder of the present invention.

[0006] The paper "Ultrasonic C-scan Imaging Automatic Inspection System for Large Conical Forgings" published in the 9th issue of Volume 38 of the journal "Nondestructive Testing" in 2016 describes the ultrasonic inspection of large conical forgings made of metal materials and the development method of the inspection system. It can only be applied to open metal conical cylinders and cannot be applied to the composite material conical cylinders in the present invention.

[0007] The paper "Ultrasonic Penetration C-Scan Inspection Technology for Composite Gas Cylinders," published in the journal "Fiberglass / Composite Materials" No. 4, 2012, describes an ultrasonic penetration inspection method for resin-based composite gas cylinders. This method is applicable only to composite gas cylinders with closed ends and a small inner diameter. It can only detect delamination and debonding defects of Φ10mm in components, and the detection sensitivity cannot reach the 5mm*5mm requirement. Furthermore, it can only determine the horizontal position of the defect, not the depth and nature of the defect, making it inapplicable to the composite conical cylinder of the present invention.

[0008] Currently, ultrasonic testing is a commonly used nondestructive testing method for composite materials. However, when using conventional ultrasonic testing methods to inspect the internal quality of composite cone cylinders, the following problems arise due to the particularity of their structure: ultrasonic signals have difficulty penetrating the composite layer, the closed small-end water spray method is difficult to detect, it is difficult to determine the defect type, and high detection sensitivity is required. Summary of the Invention

[0009] In order to overcome the deficiencies of the prior art, the present invention provides an ultrasonic testing method for a composite material cone cylinder, thereby realizing ultrasonic non-destructive testing of the internal quality of the composite material cone cylinder.

[0010] The present invention discloses an ultrasonic testing method for a composite material conical cylinder. The ultrasonic testing equipment is an ultrasonic C-scanning device having an X-axis, a Y-axis, a Z-axis, a T-axis, a θ-axis, inner and outer probes, and a probe arm. The probe is vertically connected to the probe arm. The X-axis and Y-axis are used to adjust the position of the probe arm. The Z-axis is a scanning axis used to drive the ultrasonic probe to perform scanning motion. The T-axis is a stepping axis used to drive the inspected object to rotate. The θ-axis is used to adjust the angle of the probe arm. The spacing between the inner and outer probe arms is adjustable. The ultrasonic equipment has at least two channels, each of which has reflection method and penetration method functions.

[0011] The ultrasonic detection method comprises the following steps:

[0012] Step 1: First, place the composite cone with the opening facing upward, with the axis parallel to the direction of gravity, and fill the interior with water. The internal and external ultrasonic probes and probe arms are parallel to the generatrix of the inspected part, and the probe arms drive the internal and external probes to conduct a synchronous scan.

[0013] Then adjust the detection parameters to:

[0014] a. Adjust the θ axis so that the probe arm is parallel to the direction of the busbar of the test piece and the probe sound beam is perpendicular to the direction of the busbar;

[0015] b. Adjust the X-axis and Y-axis so that the busbar of the inspected part is located between the inner and outer probe arms;

[0016] c. Set channel A of the ultrasound device to reflection mode, and connect the internal probe to channel A to transmit ultrasonic signals and receive ultrasonic reflection signals;

[0017] Set the ultrasound equipment's B channel to penetration mode, and connect the external probe to the B channel to receive the signal emitted by the internal probe and after it penetrates the test piece;

[0018] d. Adjust the distance between the probe arms so that the ultrasonic signal emitted by the internal probe is after the secondary reflection signal at the water / inner wall interface and the outer wall reflection signal, avoiding the interference of the secondary reflection signal at the water / inner wall interface on the detection signal, and making the focus of the external probe inside the test piece to ensure detection sensitivity and lateral resolution;

[0019] e. Scan along the Z axis. The radome rotates by one scan line spacing for each scan line. The scan line spacing is no more than 2mm, and the sampling spacing is no more than 1mm.

[0020] f. Sensitivity setting: Adjust the gain value of channel A of the ultrasonic equipment so that the amplitude of the reflected signal from the outer wall of the normal area of ​​the inspected object is 80%. At this time, the gain value is dB1;

[0021] Adjust the gain value of channel B of the ultrasonic equipment so that the amplitude of the penetration signal in the normal area of ​​the test piece is 100%. The gain value at this time is dB2;

[0022] g. Gate settings:

[0023] A channel setting: Use the tracking gate to frame the reflection signal of the inner wall of the inspected part, use the signal extraction gate to frame the thickness range, and extract the delamination signal;

[0024] B channel setting: Use the signal extraction gate to frame the penetration signal and extract the penetration signal;

[0025] Step 2: Scan according to the detection parameters, extract the reflection signal of the internal ultrasonic probe inside the test object, perform ultrasonic C-scan imaging, and obtain an ultrasonic C-scan grayscale image representing the internal stratification, which is set as image A;

[0026] Extract the signal received by the external ultrasonic probe from the internal ultrasonic probe that penetrates the test piece to perform ultrasonic C-scan imaging, and obtain an ultrasonic C-scan grayscale image representing all internal defects, which is set as image B;

[0027] Step 3, convert the RGB value of each coordinate point in image A into 255-RGB to obtain image C;

[0028] Step 4: Add the RGB value of each position in image B to the RGB value of the corresponding position in image C to obtain an ultrasonic C scan image representing the internal porosity defect of the inspected part, which is set as image D;

[0029] Step 5: The original ultrasonic C-scan image is geometrically corrected to obtain the image that matches the actual object under test. Figure 1Ultrasound C-scan image.

[0030] Furthermore, in step 5, the original ultrasonic C-scan image is geometrically corrected, specifically, the coordinates (X, Y) of the original ultrasonic C-scan image are corrected to (Xm, Ym). The correction formula is as follows:

[0031] ;

[0032] hour: ;

[0033] hour: ;

[0034] Where X is the abscissa of the original ultrasonic C-scan image, Y is the ordinate of the original ultrasonic C-scan image, Xm is the coordinate after X correction, Ym is the coordinate after Y correction, D is the diameter of the large end of the scan, d is the diameter of the small end of the scan, and L is the scan length.

[0035] Furthermore, the external ultrasound probe is an air-coupled focused probe with a center frequency range of 200KHz-750KHz and a focal diameter range of 2mm-5mm;

[0036] The internal ultrasonic probe is a water-immersion broadband probe with a center frequency range of 100KHz-7.5MKHz, a -6dB bandwidth ≥80%, and a chip diameter range of 5mm-10mm.

[0037] Furthermore, the image A described in step 2 is imaged according to the matrix (X, Y, (100%-P1(X, Y))*255), where X is the axial position of the test piece scanned by the probe, Y is the circumferential position of the test piece scanned by the probe, P1(X, Y) is the amplitude of the extracted layered reflection signal of the signal extraction gate of channel A of the ultrasonic device at the (X, Y) position, and P1(X, Y)*255 is the corresponding grayscale value.

[0038] Furthermore, the image B described in step 2 is imaged according to the matrix (X, Y, P2(X, Y)*255), where X is the axial position of the test piece scanned by the probe, Y is the circumferential position of the test piece scanned by the probe, P2(X, Y) is the extracted penetration signal amplitude of the signal extraction gate of the B channel of the ultrasonic device at the (X, Y) position, and P2(X, Y)*255 is the corresponding grayscale value.

[0039] Furthermore, the image C in step 3 is imaged according to the matrix (X, Y, P1(X, Y)*255).

[0040] Furthermore, the image D in step 4 is imaged according to the matrix (X, Y, P1(X, Y)*255)+P2(X, Y)*255).

[0041] The detection methods described in this invention are high-resolution ultrasonic reflection and high-sensitivity ultrasonic penetration. The high-resolution ultrasonic reflection method is used to detect delamination defects within the test object. During detection, an internal probe is used to transmit and receive ultrasonic signals, and the water inside the test object serves as a coupling agent. The high-sensitivity ultrasonic penetration method is used to detect all defects within the test object. During detection, the internal probe transmits the ultrasonic signal, and an external ultrasonic probe receives the signal after the internal ultrasonic probe penetrates the test object. The external probe uses air as a coupling agent.

[0042] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0043] (1) The detection method of the present invention places the axis of the test piece parallel to gravity, fills the interior with water, and removes bubbles in the water and on the inner wall of the test piece. The internal ultrasonic signal coupling is performed by water immersion. Placing the axis parallel to gravity ensures that the water does not overflow, which can ensure a stable coupling effect. Compared with water spray coupling, the internal ultrasonic signal coupling is performed by water immersion. First, it can eliminate the complex circulating water system. Second, water immersion coupling can eliminate the water spray tooling, allowing the probe to detect small diameter tips. The external ultrasonic probe adopts air coupling, eliminating the inconvenience caused by the use of liquid coupling agent.

[0044] (2) The detection method of the present invention uses the ultrasonic signal excited by the internal probe to simultaneously perform high-resolution ultrasonic reflection method and high-sensitivity ultrasonic penetration method detection. The internal ultrasonic probe is a water-immersed broadband probe with a center frequency range of 100KHz-7.5MKHz and a -6dB bandwidth of ≥80%. The high-frequency part of the ultrasonic wave is used for the high-resolution ultrasonic reflection method, and the low-frequency part of the ultrasonic wave is used for the high-sensitivity ultrasonic penetration method. In the high-resolution ultrasonic reflection method, the internal probe is used to transmit the ultrasonic signal during detection and receive the reflected ultrasonic signal of the transmitted signal propagating through the test piece. The delamination defects inside the test piece are detected based on the reflected signal received by the internal probe. In the high-sensitivity ultrasonic penetration method, the internal probe transmits the ultrasonic signal and the external ultrasonic probe receives the signal after the internal ultrasonic probe penetrates the test piece. All defects inside the test piece are detected based on the received signal of the internal probe. This solves the problem of not being able to implement the reflection method and the penetration method simultaneously.

[0045] (3) The detection method of the present invention can directly display delamination defects through image A and porosity defects through image D. This solves the problem of being unable to determine the defect type through ultrasonic C-scan images.

[0046] (4) The detection method of the present invention is to obtain the original ultrasonic C-scan image through geometric correction and expand it to the actual object under test. Figure 1The consistent ultrasonic C-scan image solves the problem of inconsistency between the cone-shaped ultrasonic C-scan image and the actual unfolded image of the inspected part, making the ultrasonic C-scan image more accurate.

[0047] In summary, the detection method provided by the present invention solves the technical problem that the existing ultrasonic detection method cannot detect the internal delamination and looseness defects of the composite material cone cylinder in a one-time, rapid, accurate and highly sensitive manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of ultrasonic testing of composite cone cylinder;

[0049] Figure 2 This is a schematic diagram of the connection of the ultrasound equipment;

[0050] Figure 3 is a schematic diagram of ultrasonic signals;

[0051] Figure 4 Image A is an ultrasound C scan;

[0052] Figure 5 Image B is ultrasound C scan;

[0053] Figure 6 Image C is an ultrasound C scan;

[0054] Figure 7 Image D is an ultrasound C scan;

[0055] Figure 8 It is the original ultrasound C-scan image;

[0056] Figure 9 This is the corrected ultrasound C-scan image.

[0057] In the figure, 1 is a composite cone cylinder, 2 is a probe arm, 3 is an internal ultrasonic probe, 4 is an external ultrasonic probe, 5 is an ultrasonic device, 6-1 is a transmitting end of channel A, 6-2 is a receiving end of channel B, 7 is a display screen of channel A, 8 is a display screen of channel B, 9 is a reflection signal of the inner wall of the composite cone cylinder, 10 is a delamination signal inside the composite cone cylinder, 11 is a reflection signal of the outer wall of the composite cone cylinder, 12 is a secondary reflection signal of the inner wall of the composite cone cylinder, 13 is an interface tracking gate of channel A, 14 is a signal extraction gate of channel A, 15 is a penetration signal, 16 is a signal extraction gate of channel B, 17 is an ultrasonic C-scan of image A, 18 is an ultrasonic C-scan of image B, 19 is an ultrasonic C-scan of image C, 20 is an ultrasonic C-scan of image D, 21 is an original ultrasonic C-scan of image D, 22 is a corrected ultrasonic C-scan of image D DETAILED DESCRIPTION

[0058] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the present invention is not limited thereto.

[0059] Example 1

[0060] Taking the ultrasonic testing of a glass fiber reinforced polyimide resin-based composite tapered cylinder with a wall thickness of 2 mm, an outer diameter of 350 mm at the large end, a closed tip at the small end, and a length of 600 mm as an example, the testing method steps are as follows:

[0061] Step 1, refer to Figure 1 The composite cone cylinder 1 of the test piece is placed with its opening facing upwards, with its axis parallel to the direction of gravity. The internal cavity of the composite cone cylinder 1 is filled with water, and bubbles in the water and on the inner wall of the test piece are removed. The axis is placed parallel to gravity to ensure that water does not overflow, thus ensuring a stable coupling effect. The ultrasonic signal is coupled internally by water immersion. Compared with water spray coupling, this method can eliminate the need for a complex circulating water system and the need for water spray tooling, allowing the probe to detect small-diameter tips.

[0062] Determine the ultrasonic C-scanning equipment and ultrasonic probe: the equipment has an X-axis, Y-axis, Z-axis, T-axis, θ-axis, probes 3, 4 and probe arm 2; probes 3, 4 are vertically connected to the probe arm 2, the X-axis and Y-axis are used to adjust the position of the probe arm 2, the Z-axis is the scanning axis, used to drive the ultrasonic probe to perform scanning movement, the T-axis is the stepping axis, used to drive the inspected object to rotate, and the θ-axis is used to adjust the angle of the probe arm 2 to ensure that the probe arm 2 is parallel to the busbar direction of the inspected object while making the probe sound beam perpendicular to the busbar direction. The distance between the inner and outer probe arms 2 is adjustable; the ultrasonic equipment 5 has two channels, each channel has reflection method and penetration method functions, such as Figure 2 As shown;

[0063] The external ultrasonic probe 4 is an air-coupled focused probe with a center frequency of 500 kHz and a focal diameter of 2 mm. The air coupling method of the external ultrasonic probe 4 eliminates the inconvenience caused by the use of liquid coupling agent. The internal ultrasonic probe 3 is a water-immersed broadband probe with a center frequency of 5 kHz, a -6 dB bandwidth of 85%-100%, and a chip diameter of 5 mm.

[0064] Determine the detection method: The detection methods are high-resolution ultrasonic reflection method and high-sensitivity ultrasonic penetration method; the high-resolution ultrasonic reflection method is used to detect delamination defects inside the composite material cone cylinder 1. During detection, the internal ultrasonic probe 3 is used to transmit and receive ultrasonic signals, and the water in the composite material cone cylinder 1 is a coupling agent; the high-sensitivity ultrasonic penetration method is used to detect all defects inside the composite material cone cylinder 1. During detection, the internal ultrasonic probe 3 transmits ultrasonic signals, and the external ultrasonic probe 4 receives the signals after the internal ultrasonic probe 3 penetrates the composite material cone cylinder 1. The external ultrasonic probe 4 uses air as a coupling agent, eliminating the inconvenience caused by the use of liquid coupling agents; the present invention uses the ultrasonic signal excited by the internal ultrasonic probe 3 to simultaneously perform high-resolution ultrasonic reflection method and high-sensitivity ultrasonic penetration method detection. The internal ultrasonic probe 3 is a water-immersed broadband probe. The high-frequency part of the ultrasonic wave is used for the high-resolution ultrasonic reflection method, and the low-frequency part of the ultrasonic wave is used for the high-sensitivity ultrasonic penetration method, which solves the problem of not being able to realize the reflection method and the penetration method at the same time;

[0065] Determine the basic test parameters: adjust the θ axis so that the probe arm 2 is parallel to the generatrix of the test piece; adjust the X and Y axes so that the generatrix of the composite cone 1 is located between the inner and outer probe arms 2;

[0066] Reference Figure 2 , set the A channel of the ultrasonic device 5 to the reflection method mode, and connect the internal ultrasonic probe 3 to the transmitting end 6-1 of the A channel of the ultrasonic device 5 to transmit ultrasonic signals and receive ultrasonic reflection signals;

[0067] Set channel B to penetration mode, and connect the external ultrasonic probe 4 to the receiving end 6-2 of channel B of the ultrasonic device 5 to receive the signal emitted by the internal ultrasonic probe 3 after penetrating the composite cone 1. The ultrasonic device 5 is also equipped with a channel A display screen 7 and a channel B display screen 8, which can be used to observe the display information of the two channels.

[0068] Reference Figure 1 and Figure 3 , adjust the distance between the probe arms 2 so that the ultrasonic signal emitted by the internal ultrasonic probe 3 is reflected after the secondary reflection signal 12 at the internal water / inner wall interface and the reflection signal 11 from the outer wall of the composite cone cylinder, avoiding the interference of the secondary reflection signal 12 at the water / inner wall interface on the internal delamination signal 10 of the composite cone cylinder, and making the focus of the external ultrasonic probe 4 inside the composite cone cylinder 1, thereby ensuring the detection sensitivity and lateral resolution;

[0069] Scanning is performed along the Z axis. The radome rotates by one scanning line spacing for each scanning line. The scanning line spacing is 2mm and the sampling spacing is 1mm.

[0070] Sensitivity setting: Adjust the gain value of channel A of the ultrasonic device 5 so that the amplitude of the outer wall reflection signal 11 in the normal area of ​​the composite cone cylinder 1 is 80%, and the gain value at this time is dB1; adjust the gain value of channel B of the ultrasonic device 5 so that the amplitude of the penetration signal in the normal area of ​​the composite cone cylinder 1 is 100%, and the gain value at this time is dB2;

[0071] Reference Figure 3 , Gate setting: A channel setting: Use tracking gate 13 to frame the reflection signal 9 of the inner wall of the composite cone cylinder, use signal extraction gate 14 to frame the thickness range, and extract the internal delamination signal 10;

[0072] B channel setting: Use signal extraction gate 16 to frame penetration signal 15 and extract penetration signal 15.

[0073] Step 2: Scan according to the determined detection method and basic detection parameters, extract the internal ultrasonic probe 3 and perform ultrasonic C-scan imaging on the internal delamination signal 10 of the composite cone cylinder 1, and obtain an ultrasonic C-scan grayscale image of the internal delamination, which is set as image A. Figure 4 , the serial number of image A is 17, image A (17) is imaged according to the matrix (X, Y, (100%-P1(X, Y))*255), X is the axial position of the composite cone cylinder 1 scanned by the probe, Y is the circumferential position of the composite cone cylinder 1 scanned by the probe, P1(X, Y) is the amplitude of the extracted layered reflection signal 10 of the signal extraction gate 14 of the A channel of the ultrasonic device 5 at the (X, Y) position, and P1(X, Y)*255 is the corresponding grayscale value;

[0074] Extract the signal received by the external ultrasonic probe 4 from the internal ultrasonic probe 3 penetrating the composite cone 1 to perform ultrasonic C-scan imaging, and obtain the ultrasonic C-scan grayscale image of all internal defects, which is set as image B. Figure 5 , the serial number of image B is 18, and image B (18) is imaged according to the matrix (X, Y, P2(X, Y)*255), where X is the axial position of the test piece scanned by the probe, Y is the circumferential position of the test piece scanned by the probe, P2(X, Y) is the extracted penetration signal amplitude 15 of the signal extraction gate 16 of the B channel of the ultrasonic device 5 at the (X, Y) position, and P2(X, Y)*255 is the corresponding grayscale value.

[0075] Step 3: Convert the RGB value of each coordinate point in image A (17) to 255-RGB to obtain image C, see Figure 6 , the serial number of image C is 19, and image C (19) is imaged according to the matrix (X, Y, P1(X, Y)*255).

[0076] Step 4, add the RGB value of each position in image B (18) to the RGB value of the corresponding position in image C (19), and obtain an ultrasonic C-scan image representing the internal porosity defect of the composite cone 1, which is set as image D. Figure 7 , the serial number of image D is 20; the delamination defect can be directly displayed through image A (17), and the looseness defect can be directly displayed through image D (20), which solves the problem of being unable to determine the defect type through ultrasonic C-scan images.

[0077] Step 5: The original ultrasound C-scan image 21, see Figure 8 , obtained by geometric correction and the composite cone 1 Figure 1 The corresponding ultrasound C-scan Figure 22;

[0078] The geometric correction is to correct the coordinates (X, Y) of the original ultrasound C-scan image to (Xm, Ym). The correction formula is as follows:

[0079] ;

[0080] hour: ;

[0081] hour: .

[0082] The method of the present invention was used to test an actual product of a glass fiber reinforced polyimide resin-based composite tapered cylinder. The test results and actual dissection results are shown in Table 1.

[0083] Table 1 Detection defects

[0084] Serial number Test results (mm*mm) Actual anatomical results (mm*mm) 1 4*5 layers 4*4 layers 2 6*8 layers 4*6 layers 3 9*10 loose 8*10 loose

[0085] The results show that the method of the present invention solves the problem of inconsistency between the ultrasonic C-scan image of the cone cylinder and the actual unfolded view of the inspected part, making the ultrasonic C-scan image more accurate.

[0086] Example 2

[0087] Taking the ultrasonic detection of a carbon fiber reinforced bismaleimide resin-based composite tapered cylinder with a wall thickness of 9 mm, an outer diameter of 400 mm at the large end, a closed tip at the small end, and a length of 800 mm as an example, the detection method steps are the same as those in Example 1, except that:

[0088] In step 1, the external ultrasonic probe 4 is an air-coupled focused probe with a center frequency of 400 kHz and a focal diameter of 2 mm. The external ultrasonic probe 4 uses air coupling, eliminating the inconvenience caused by the use of liquid coupling agent. The internal ultrasonic probe 3 is a water-immersed broadband probe with a center frequency of 2.25 kHz, a -6 dB bandwidth of 80%-100%, and a chip diameter of 7.5 mm.

[0089] Step 5: Geometric correction is to correct the coordinates (X, Y) of the original ultrasonic C-scan image to (Xm, Ym). The correction formula is as follows:

[0090] ;

[0091] hour: ;

[0092] hour: .

[0093] The method of the present invention was used to test an actual product of a carbon fiber reinforced bismaleimide resin-based composite tapered cylinder. The test results and actual dissection results are shown in Table 2.

[0094] Table 2 Detection defect situation

[0095] Serial number Test results (mm*mm) Actual anatomical results (mm*mm) 1 4*4 loose 3*3 loose 2 5*6 layers 4*5 layers 3 15*12 layers 13*10 layers

[0096] The results show that the method of the present invention can accurately detect internal defects of composite material conical cylinders, and the detection sensitivity is better than 4mm*4mm, which solves the technical problem that the existing ultrasonic detection method cannot quickly, accurately and highly sensitively detect the internal stratification and looseness defects of composite material conical cylinders at one time.

[0097] The contents not described in detail in the present invention are well known to those skilled in the art.

Claims

1. A method for ultrasonic testing of composite tapered cylinders, characterized by: The ultrasonic testing equipment is an ultrasonic C-scan device, which has an X-axis, Y-axis, Z-axis, T-axis, θ-axis, a probe and a probe arm; the probe is vertically connected to the probe arm, the X-axis and Y-axis are used to adjust the position of the probe arm, the Z-axis is the scanning axis, used to drive the ultrasonic probe to perform scanning movements, the T-axis is the stepping axis, used to drive the test object to rotate, and the θ-axis is used to adjust the angle of the probe arm. The spacing between the inner and outer probe arms is adjustable. The ultrasonic equipment has at least two channels, each channel has reflection method and penetration method functions; The ultrasonic detection method comprises the following steps: Step 1: First, place the composite cone with the opening facing upward, with the axis parallel to the direction of gravity, and fill the interior with water. The internal and external ultrasonic probes and probe arms are parallel to the generatrix of the inspected part, and the probe arms drive the internal and external probes to conduct a synchronous scan. Then adjust the detection parameters to: a. Adjust the θ axis so that the probe arm is parallel to the direction of the busbar of the test piece and the probe sound beam is perpendicular to the direction of the busbar; b. Adjust the X-axis and Y-axis so that the busbar of the inspected part is located between the inner and outer probe arms; c. Set channel A of the ultrasound device to reflection mode, and connect the internal probe to channel A to transmit ultrasonic signals and receive ultrasonic reflection signals; Set the ultrasound equipment's B channel to penetration mode, and connect the external probe to the B channel to receive the signal emitted by the internal probe after it penetrates the test piece. d. Adjust the distance between the probe arms so that the ultrasonic signal emitted by the inner probe is reflected twice at the water / inner wall interface after the outer wall reflection signal, avoiding the interference of the second reflection signal at the water / inner wall interface on the detection signal. The focus of the outer probe is placed inside the test piece to ensure detection sensitivity and lateral resolution. e. Scan along the Z axis. The radome rotates by one scan line spacing for each scan line. The scan line spacing is no more than 2mm, and the sampling spacing is no more than 1mm. f. Sensitivity setting: Adjust the gain value of channel A of the ultrasonic equipment so that the amplitude of the reflected signal from the outer wall of the normal area of ​​the inspected object is 80%. At this time, the gain value is dB1; Adjust the gain value of channel B of the ultrasonic equipment so that the amplitude of the penetration signal in the normal area of ​​the test piece is 100%. The gain value at this time is dB2; g. Gate settings: A channel setting: Set the tracking gate to frame the reflection signal of the inner wall of the inspected part, and set the signal extraction gate to frame the thickness range to extract the delamination signal; B channel setting: frame the penetration signal with the signal extraction gate to extract the penetration signal; Step 2: Scan according to the detection parameters, extract the reflection signal of the internal ultrasonic probe inside the test object, perform ultrasonic C-scan imaging, and obtain an ultrasonic C-scan grayscale image representing the internal stratification, which is set as image A; Extract the signal received by the external ultrasonic probe from the internal ultrasonic probe that penetrates the test piece to perform ultrasonic C-scan imaging, and obtain an ultrasonic C-scan grayscale image representing all internal defects, which is set as image B; The external ultrasonic probe is an air-coupled focused probe with a center frequency range of 200KHz-750KHz and a focus diameter range of 2mm-5mm; The internal ultrasonic probe is a water-immersed broadband probe with a center frequency range of 100KHz-7.5MKHz, a -6dB bandwidth ≥80%, and a chip diameter range of 5mm-10mm; Step 3, convert the RGB value of each coordinate point in image A into 255-RGB to obtain image C; Step 4: Add the RGB value of each position in image B to the RGB value of the corresponding position in image C to obtain an ultrasonic C scan image representing the internal porosity defect of the inspected part, which is set as image D; Step 5: geometrically correct the original ultrasonic C-scan image to obtain an ultrasonic C-scan image that is consistent with the actual unfolded image of the inspected part; The geometric correction of the original ultrasonic C-scan image is specifically performed by correcting the coordinates (X, Y) of the original ultrasonic C-scan image to (Xm, Ym). The correction formula is as follows: hour: hour: Where X is the abscissa of the original ultrasonic C-scan image, Y is the ordinate of the original ultrasonic C-scan image, Xm is the coordinate after X correction, Ym is the coordinate after Y correction, D is the diameter of the large end of the scan, d is the diameter of the small end of the scan, and L is the scan length.

2. The ultrasonic testing method for composite tapered cylinders according to claim 1, characterized in that: The image A described in step 2 is imaged according to the matrix (X, Y, (100%-P1(X, Y))*255), where X is the axial position of the test piece scanned by the probe, Y is the circumferential position of the test piece scanned by the probe, P1(X, Y) is the amplitude of the extracted layered reflection signal of the signal extraction gate of channel A of the ultrasonic device at the (X, Y) position, and P1(X, Y)*255 is the corresponding grayscale value.

3. The ultrasonic testing method for composite tapered cylinder according to claim 1, characterized in that: The image B described in step 2 is imaged according to the matrix (X, Y, P2(X, Y)*255), where X is the axial position of the test piece scanned by the probe, Y is the circumferential position of the test piece scanned by the probe, P2(X, Y) is the extracted penetration signal amplitude of the signal extraction gate of the B channel of the ultrasonic device at the (X, Y) position, and P2(X, Y)*255 is the corresponding grayscale value.

4. The ultrasonic testing method for composite tapered cylinders according to claim 1, characterized in that: The image C described in step 3 is imaged according to the matrix (X, Y, P1(X, Y)*255).

5. The ultrasonic testing method for composite tapered cylinder according to claim 1, characterized in that: The image D described in step 4 is imaged according to the matrix (X, Y, P1(X, Y)*255+P2(X, Y)*255).

Images