Phased array water immersion ultrasonic linear scanning phantom wave suppression method and system

Abstract

The invention discloses a phased array water immersion ultrasonic linear scanning phantom wave suppression method and system, and relates to the technical field of ultrasonic nondestructive testing. According to the method, aiming at the problem of phantom wave interference under high repetition frequency, a reversible mapping function of logic and physical sequence numbers is defined to disrupt the emission sequence of synthetic beams and destroy periodic superposition of phantom waves, so that phantom wave interference is inhibited. According to the technical scheme, parameters such as water distance and focusing depth are set; determining an activated wafer set; calculating a delay rule of each wafer; configuring an out-of-order transmitting mode based on the mapping function; and receiving and rearranging the echo data to generate a detection image. According to the method, the signal-to-noise ratio can be remarkably improved, the defect recognition accuracy under the 5000 Hz repetition frequency is improved by 40%, the detection efficiency is improved by 2.5 times, and the method is suitable for high-precision C scanning of the thick-wall structure. Meanwhile, the invention further discloses a system, a storage cut-off scheme and an industrial application scheme.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic non-destructive testing, and particularly relates to a method and system for suppressing phased array immersion ultrasonic linear scanning phantom waves, which are applicable to improving the signal-to-noise ratio and efficiency of detection at high repetition frequencies. Background Art

[0002] The ultrasonic phased array detection technology is an advanced ultrasonic non-destructive testing method. By controlling the excitation time and sequence of multiple independent piezoelectric wafers, the directional emission and focusing of sound waves can be achieved. Its basic principle is to cut a composite piezoelectric wafer into several small wafers and arrange them in a certain array. Each wafer is controlled by an independent pulse emission and reception circuit. By controlling the excitation time of each wafer, the effect of controlling the wavefront can be achieved. Compared with the traditional ultrasonic detection technology, the ultrasonic phased array detection technology has the advantages of flexible and efficient detection, high precision and high resolution.

[0003] Ultrasonic linear scanning is a basic scanning method in phased array ultrasonic detection. By electronically sequentially exciting a group of wafers (i.e., sub-apertures) in the transducer array, the sound beam is linearly translated along the length direction of the transducer, thereby covering the detection method of the area to be detected. Phantom waves refer to echo signals that may be generated when using a relatively high ultrasonic repetition frequency in ultrasonic detection (especially phased array detection), and are extremely similar to defect echoes. Figure 1 The schematic diagram of the generation principle of phantom waves is shown. As shown in the figure, when the ultrasonic signal propagation time T is greater than the ultrasonic wave repetition emission period T0, the received echo signal just enters the ultrasonic signal gate range of the next detection cycle. The ultrasonic detection device will calculate the damage position according to the time T1 of the ultrasonic emission start wave pulse in the next emission cycle, thereby forming phantom waves. The actual workpiece to be detected does not have this defect, which proves that the existence of phantom waves will affect the accuracy of the workpiece detection result. After verification, this kind of echo is not caused by defects or workpiece deformation, but is a non-defect echo caused by comprehensive factors such as the detection device and the workpiece material. In order to improve the detection efficiency, it is usually necessary to use a high repetition frequency for fast linear scanning to reduce the detection time and increase the data acquisition rate. However, too high a repetition frequency may lead to the generation of phantom waves (such as reverberation artifacts, sidelobe interference, etc.), affecting the signal-to-noise ratio and defect recognition accuracy. In order to suppress the interference of phantom waves, it is often necessary to reduce the repetition frequency, but this will lead to a decrease in detection efficiency.

[0004] The existing phantom wave suppression method is to apply control signals with different frequencies to the piezoelectric wafer in two adjacent emission cycles. After emitting ultrasonic waves in each emission cycle and before emitting ultrasonic waves in the next emission cycle, the piezoelectric wafer is controlled to receive the reflected echo reflected by the detected workpiece from the ultrasonic waves emitted in the current emission cycle. According to the control signal frequency corresponding to each emission cycle, the reflected echo corresponding to the ultrasonic waves emitted by the piezoelectric wafer in each emission cycle is filtered to obtain the filtered signal corresponding to each emission cycle. When the amplitude of the filtered signal corresponding to any emission cycle exceeds the preset threshold, it is determined that there is a defect in the detected workpiece. The above solution determines whether there is a defect by applying signals with different control frequencies to the piezoelectric wafer and performing post-signal processing on the reflected echo received in the next emission cycle. There are the following technical limitations in adopting this solution: 1. High equipment requirements: The emission frequency of a conventional transducer is fixed and cannot meet the requirements of the solution; 2. Heavy data analysis burden: The original waveform data needs to be subjected to complex post-processing to extract defect features, resulting in an increase in the amount of calculation; 3. Low signal processing efficiency: Different position information needs to be obtained by repeated emissions multiple times, resulting in insufficient signal utilization rate.

[0005] It should be noted that the information disclosed in this background art section is only intended to deepen the understanding of the overall background art of the present invention, and should not be regarded as an admission or any form of suggestion that this information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0006] Aiming at the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a phased array immersion ultrasonic linear scanning phantom wave suppression method and system, which defines a phased array synthesized beam electronic scanning mode of "disordered" emission. By disrupting the emission order of the synthesized beam, the periodic superposition condition of the phantom wave is destroyed, and the suppression of the phantom wave is realized without reducing the repetition frequency and without performing reference matching.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a phased array immersion ultrasonic linear scanning phantom wave suppression method, including the following steps:

[0009] 1. Parameter configuration and wafer activation: Set the water distance h, the focusing depth f, and the number of activated wafers N

[0011] ,

[0010] , ,

[0009] , Active , , i , and determine the set of activated wafers for each synthesized beam in the linear scanning;

[0010] 2. Delay rule calculation: Based on the sound velocity c1 of the water medium, the sound velocity c2 of the workpiece to be measured, and the element spacing d, calculate the excitation / reception delay Δt i of each activated wafer to ensure acoustic focusing;

[0011] 3. Definition of out-of-order emission mode: Construct a reversible mapping function f between logical sequence numbers and physical sequence numbers order , and disrupt the generation rule of phantom waves by non-periodic prior emission order:

[0012] When the total number of synthesized beams N Beam is odd, define N Half = N Beam / 2 + 1. For the logical sequence number i:

[0013] If i < N Half , then f order (i) = 2i;

[0014] If i = N Half , then f order (i) = i;

[0015] If i > N Half , then f order (i) = 2×(i - N Half );

[0016] When N Beam is even, define N Half = N Beam / 2. For the logical sequence number i:

[0017] If i ≤ N Half , then f order (i) = 2×(i - 1) + 1;

[0018] If i > N Half , then f order (i) = 2×(i - N Half );

[0019] 4. Data acquisition and processing: After receiving the original echo data, rearrange it according to the logical sequence number, and generate B-mode and C-mode display images using a two-dimensional image algorithm to suppress phantom wave interference.

[0020] In a second aspect, the present invention provides a phased array ultrasonic detection system for implementing the method in the first aspect above, including:

[0021] A linear phased array transducer, including N Element array elements;

[0022] An ultrasonic host configured to generate synthesized beams in an out-of-order emission mode;

[0023] A mechanical scanning device for driving the transducer to complete raster scanning;

[0024] A data processing unit for rearranging echo signals and generating images.

[0025] In a third aspect, the present invention provides a computer-readable storage medium storing a computer program, which when executed by a processor implements the steps of the method according to the first aspect above.

[0026] In a fourth aspect, the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory, and when the processor executes the program, it implements the steps of the method according to the first aspect above.

[0027] In a fifth aspect, the present invention provides an industrial non-destructive testing method, which uses the phantom wave suppression method according to the first aspect above to perform water-immersion ultrasonic linear scanning testing on a thick-wall structure.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1. Phantom wave suppression: By means of a non-periodic emission mode, the amplitude of the phantom wave is suppressed below the noise level, and the signal-to-noise ratio is increased by more than 50%.

[0030] 2. Efficiency improvement: At a high repetition frequency of 5000 Hz, the detection efficiency is increased by 2.5 times compared with the traditional sequential mode, and the defect recognition accuracy is increased by 40%.

[0031] 3. Universality: It is applicable to water-immersion ultrasonic C-scan testing of thick-wall structures such as nuclear power pipelines and aerospace components, and is compatible with existing phased array equipment.

[0032] [[ID=2l]]4. Expandability: It provides a system, a storage medium, and an industrial detection solution, and supports automated integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Shows a schematic diagram of the principle of phantom wave generation; [[ID=..]]

[0034] Figure 2 Shows a setting diagram of software operation parameters in Embodiment 1;

[0035] Figure 3 Shows the mapping function f order of the logic flow chart;

[0036] Figure 4 Shows a comparison diagram of the emission sequences of sequential scanning and disordered scanning;

[0037] Figure 5 Shows the parameter configurations of "sequential" scanning and "disordered" scanning in the array ultrasonic detection software;

[0038] Figure 6 Shows the comparison results of A-scan signals obtained by respectively performing "sequential" scanning and "disordered" scanning modes on a test specimen based on a water-immersion phased array ultrasonic detection system;

[0039] Figure 7 The comparison results of B-scan signals obtained by performing "sequential" scanning and "random" scanning modes on the test sample based on the immersion phased array ultrasonic testing system are shown.

[0040] Figure 8 The comparison results of C-scan signals obtained by performing "sequential" scanning and "random" scanning modes on the test sample based on the immersion phased array ultrasonic testing system are shown. DETAILED DESCRIPTION

[0041] The following is a more detailed description of the technical features and advantages of the present invention in conjunction with the embodiments and drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0042] Example 1

[0043] A method for suppressing phantom waves in phased array water immersion ultrasonic linear scanning includes the following steps:

[0044] Step 1: Set the water distance h, the focus depth f of the synthetic beam, and the number of activated crystals N for the synthetic beam used in linear scanning detection. Active .

[0045] Specifically, the detection water distance h = 30mm, the focus depth of the synthetic beam f = 15mm, and the number of synthetic beam activated chips N Active =14, the number of elements of the linear phased array transducer N Element =128, array element spacing d = 0.5mm. Software operating parameters are set as follows Figure 2 shown.

[0046] Step 2: Determine the active element set of each synthetic beam during linear scanning. Element The linear phased array transducer with array element chips has the following activated chip sets: {1,2,…,N Active},{2,3,…,N Active +1},…,{N Element -N Active +1,N Element -N Active +2,…,N Element}, there are N Beam =N Element -N Active +1 synthetic beam.

[0047] In this embodiment, the activated chip sets are: {1, 2, ..., 14}, {2, 3, ..., 15}, ..., {115, 116, ..., 128}, a total of N Beam =115 synthetic beams.

[0048] Step 3: Calculate the delay law Δt of the synthetic beam excited by the wafer set {1, 2, …, 14} i (i = 1, 2, …, N Active )

[0049] First, calculate the transit time Tof of the ultrasonic ray from the activated wafer to the focus point i (i = 1, 2, …, N Active ), and its calculation formula satisfies:

[0050]

[0051] In formula (1), c1 and c2 are the sound velocities of water and the specimen under test respectively, d is the element wafer pitch of the linear phased array transducer, and the excitation / reception delay Δt of the i-th element wafer i can be expressed as:

[0052]

[0053] Specifically, c1 = 1480 m / s, c2 = 6300 m / s, and according to formulas (1) and (2), the delay law Δt corresponding to each activated wafer can be calculated i , and the results are shown in the following table

[0054] Table 1 Calculation results of the delay law for each activated wafer

[0055]

[0056]

[0057] Step 4: Calculate the delay laws of other synthetic beams. Since the same number of activated wafers and the same focusing depth are used for all synthetic beams during linear scanning, the delay laws of all synthetic beams are the same as those of the wafer set {1, 2, …, 14}

[0058] Step 5: Define the invertible mapping function f between the sets {1, 2, …, N Beam} and {1, 2, …, N Beam} order .

[0059] Step 6: Define the logical sequence number and physical sequence number of the synthetic beam. For the synthetic beam with the activated wafer set {i, i + 1, …, N Active + i - 1}, its logical sequence number is i, and the physical sequence number is f order (i), and there is i = f order -1 (f order (i)).

[0060] When N Beam is odd, define N Half = N Beam / 2 + 1:

[0061] When i < N Half , f order (i) = 2i;

[0062] When i = N Half , f order (i) = 1;

[0063] When i > N Half , f order (i) = 2×(i - N Half ); + 1

[0064] When N Beam is even, define N Half = N Beam / 2:

[0065] When i <= N Half , f order (i) = 2×(i - 1) + 1;

[0066] When i > N Half , f order (i) = 2×(i - N Half ); f order The logic block diagram of f Figure 3 .

[0067] Specifically, N Beam is odd, N Half = 58. When i < 58, f order (i) = 2i; When i = 58, f order (i) = 1; When i > 58, f order (i) = 2×(i - 58) + 1.

[0068] Step 7: Configure the total number of synthetic beams emitted when the phased array ultrasound host works and the serial numbers of the activated wafers used for each synthetic beam. The total number of synthetic beams is equal to N Beam , and the serial numbers of the activated wafers used for the j-th transmitted synthetic beam are the set {f order -1 (j), f order -1 (j) + 1,..., N Active + f order -1}(j) - 1.

[0069] Specifically, the serial numbers of the activated wafers used for the first synthetic beam emission are the set {58, 59, …, 71}. The following table lists the serial numbers of the different wafers activated by the "sequential emission" mode and the "random emission" mode for the first 9 synthetic beam emissions. More data can be calculated with reference to Step 6.

[0070] Table 2 Serial numbers of different wafers activated by the "sequential emission" mode and the "random emission" mode

[0071]

[0072]

[0073] Step 8: Configure the delay rule for the excitation and reception of each synthetic beam when the phased array ultrasound host is working. The excitation delay and reception delay used for the i-th activated wafer are Δt i and max(Δt j ) - Δt i . Switch to the "random" emission mode in the software beam arrangement operation bar, as Figure 5 shown.

[0074] Step 9: Receive the raw echo data of the phased array ultrasound host, denoted as the two-dimensional array Ascan_Raw[N Beam [N t where N t is the number of received acquisition points of the echo signal of each synthetic beam, and Ascan_Raw[i][N t corresponds to the echo signal of the synthetic beam with the physical serial number i.

[0075] Step 10: Reorder the raw echo data so that it is arranged according to the logical serial number of the synthetic beam. The echo data arranged according to the logical serial number is the two-dimensional array AScan[N Beam [N t , then AScan[i][j] = AScan_Raw[f order (i)][j].

[0076]

[0077] Step 11: Regard AScan[N Beam [N t as a two-dimensional image, and use a two-dimensional image algorithm for visual display on the computer screen to obtain an ultrasonic electronic linear scan B-mode display image. Figure 7

[0078] Specifically, the raw echo data collected from the test piece is processed and an ultrasonic electronic linear scan B-mode display image is obtained using a two-dimensional image algorithm, as Figure 7 shown.

[0078] Step 12: Use a mechanical scanning device to drive a linear phased array transducer to complete the full-area raster C-scan inspection of the test specimen. Assume the number of points on the scanning axis is N scan , and the number of points on the stepping axis is N index . At each mechanical scanning point, trigger the phased array ultrasonic host through an encoder to transmit and receive the synthesized beam according to Steps 8-9, process the echo data according to Step 10, and finally generate an ultrasonic electronic linear scanning C-scan two-dimensional image of N scan ×(N index ×N Beam ). The calculation method of the gate for each pixel point in the C-scan image can be performed with reference to the corresponding detection standard.

[0079] Specifically, complete the full-area raster C-scan inspection of the test specimen to obtain the final ultrasonic electronic linear scanning C-scan two-dimensional image, as Figure 7 shown.

[0080] The method of the embodiment of the present invention can suppress the generation of phantom waves at high pulse repetition frequencies and greatly improve the phased array immersion electronic linear C-scan inspection efficiency of thick-walled structures. Refer to the appendix Figures 6 - 8 . When the repetition frequency is 5000 Hz, the "sequential" emission mode will generate phantom waves due to acoustic wave superposition, while the "random" emission can effectively suppress phantom waves. When the repetition frequency is reduced to 2000 Hz, the phantom waves in the "sequential" emission mode disappear, and the detection signal-to-noise ratio is equivalent to that of the "sequential" emission mode, but the detection efficiency of the latter is about 2.5 times that of the former.

[0081] Figure 4 shows a comparison diagram of the excitation sequences of phased array line scans in the "sequential" scan and "random" scan. As shown in the figure, the numbers represent the excitation sequences of the synthesized sound beams. When the "sequential" scan is selected, the synthesized sound beam performs a linear translational electronic scan along the length direction of the transducer. When the "random" scan is selected, the excitation sequence of the synthesized sound beam can be determined according to Steps 5, 6, and 7 in the basic concept.

[0082] Figure 6 shows the comparison results of A-scan signals obtained by performing "sequential" scans and "random" scans on the test specimen using an immersion phased array ultrasonic detection system. Experimental studies have shown that at the same detection position, in the "sequential" scan mode, due to the periodic law of the element excitation timing, phantom waves highly similar to the characteristics of real defect echoes will be induced. In contrast, the "random" scan suppresses the phantom wave amplitude below the noise level through the design of non-periodic element excitation timing. On the premise of ensuring the detection repetition frequency, it significantly improves the spatial resolution and signal-to-noise ratio stability of defect detection, providing a technical guarantee for high-precision quantitative detection.

[0083] Figure 7Shows the comparison results of B-scan signals obtained by performing "sequential" scanning and "random" scanning modes on the test specimen based on a water-immersion phased array ultrasonic testing system. Figure 8 Shows the comparison results of C-scan signals obtained by performing "sequential" scanning and "random" scanning modes on the test specimen based on a water-immersion phased array ultrasonic testing system. Obvious phantom echo artifacts can be seen in the image obtained by "sequential" scanning, seriously interfering with the evaluation of the true distribution of defects. While "random" scanning significantly suppresses such artifacts, which is beneficial to the qualitative analysis and quantitative evaluation of defects.

[0084] The above are only embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A phased array water immersion ultrasonic linear scanning phantom wave suppression method, characterized in that, Including the following steps: (a) Set the linear scanning detection parameters, including the water distance h, the synthetic beam focusing depth f, and the number of activated wafers N Active ; (b) Determine the set of activated wafers for each synthetic beam during linear scanning. For a linear phased array transducer with N Element element wafers, the sets of activated wafers are respectively: {1, 2, …, N Active}, {2, 3, …, N Active + 1}, …, {N Element - N Active + 1, N Element - N Active + 2, …, N Element}, and there are a total of N Beam = N Element - N Active + 1 synthetic beams; (c) Calculate the delay rule Δt of each activated wafer set i ; (d) Define the invertible mapping function f between the logical sequence number i and the physical sequence number f of the synthesized beam order (i) order , and the mapping function is used to shuffle the transmission order of the synthesized beam. For the synthesized beam with the active wafer set {i, i + 1, …, N Active + i - 1}, its logical sequence number is i and the physical sequence number is f order (i), and i = f order -1 (f order (i)); (e) Configure the transmission order of the phased array ultrasound host according to the mapping function, and use the aperiodic out-of-order mode to excite the synthetic beam. The total number of synthetic beams is equal to N Beam , and the serial numbers of the activated wafers used for the j-th transmission of the synthetic beam are the set {f order -1 (j), f order -1 (j) + 1, …, N Active + f order -1 (j) - 1}; (f) Configure the delay rule for the excitation and reception of each synthetic beam when the phased array ultrasonic host works. The excitation delay and reception delay adopted by the i-th active wafer are Δt i and max(Δt j ) - Δt i ; (g) Receiving and processing the echo data to generate a detection image with suppressed ghost waves.

2. The method according to claim 1, wherein The mapping function f in step (d) order satisfies the following conditions: When the total number of synthetic beams N Beam is odd, define N Half = N Beam / 2 + 1. For the logical sequence number i: If i < N Half , then f order (i) = 2i; If i = N Half , then f order (i) = i; If i > N Half , then f order (i) = 2 × (i - N Half ) + 1; When N Beam is an even number, define N Half = N Beam / 2. For the logical sequence number i: If i ≤ N Half , then f order (i) = 2×(i - 1) + 1; If i > N Half , then f order (i) = 2 × (i - N Half ).

3. The method according to claim 1, wherein The step (g) specifically includes: Rearranging the original echo data according to the logical sequence number and generating a B-mode or C-mode display image through a two-dimensional image algorithm.

4. The method according to claim 1, wherein The delay rule Δt i is calculated as follows: First, calculate the transit time Tof of the ultrasonic ray from the activated wafer to the focal point i (i = 1, 2, …, N Active ), and its calculation formula satisfies: In Equation (1), c1 and c2 are the sound velocities of water and the sample to be tested, respectively, d is the element pitch of the linear phased array transducer, and the excitation / reception delay Δt of the i-th element i can be expressed as:

5. A phased array ultrasonic testing system for implementing the method according to any one of claims 1-4, characterized in that, Including: Linear phased array transducer, including N Element array elements; An ultrasound main unit configured to generate a synthetic beam in a disordered emission mode; A mechanical scanning device for driving a transducer to complete raster scanning; A data processing unit for rearranging echo signals and generating images.

6. The system according to claim 5, wherein The ultrasound main unit includes: A programmable delay module for implementing the delay rule Δt i ; A mode switching module supporting the switching between "sequential emission" and "disordered emission" modes.

7. A computer-readable storage medium storing a computer program, characterized in that, When the program is executed by a processor, the steps of the method according to any one of claims 1-4 are implemented.

8. An electronic device, comprising a memory, a processor, and a computer program stored on the memory, characterized in that, When the processor executes the program, the steps of the method according to any one of claims 1-4 are implemented.

9. An industrial non-destructive testing method, characterized in that, Performing water-immersion ultrasonic linear scanning detection on a thick-wall structure by using the ghost wave suppression method according to any one of claims 1-4.

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