HBO-based pipeline welding defect ultrasonic detection signal compensation method

Abstract

The invention relates to an HBO-based pipeline welding defect ultrasonic detection signal compensation method, and belongs to the technical field of pipeline detection equipment. According to the HBO-based pipeline welding defect ultrasonic detection signal compensation method, a strategy for constructing a signal compensation dictionary database is provided, phase and amplitude compensation coefficients in all subintervals are arranged in sequence, a signal compensation coefficient set F is constructed, and finally a temperature compensation model dictionary database in a temperature environment where a pipeline is located is established. In practical engineering application, a measurement signal m (t) is guided into a temperature compensation dictionary database, according to the measurement temperature of the signal, a phase compensation coefficient # imgabs0 # and an amplitude compensation coefficient # imgabs1 # at the corresponding temperature can be obtained, temperature compensation of an ultrasonic detection signal is finally achieved, the detection accuracy of pipeline welding defects is improved, and the misjudgment rate of the defects is reduced.

Description

Technical Field

[0001] The invention relates to a pipeline welding defect ultrasonic detection signal compensation method based on HBO, belonging to the technical field of pipeline detection equipment. Background Art

[0002] At present, in pipeline weld defect detection, temperature changes will cause changes in material properties, causing signal offset (phase and amplitude). For the denoised detection signal, it is necessary to compensate the phase and amplitude of the signal at each temperature to ensure that weld defects can be detected and identified at various temperatures. There are two common signal temperature compensation methods: base signal expansion (BSS) and optimal base selection (OBS).

[0003] Baseline signal stretch BSS method: Croxford and Wilcox proposed a temperature compensation scheme, namely baseline stretch (BSS). This method only requires a reference signal and uses Fourier transform to fill the signal with zeros and truncate it to compensate for the signal phase offset. The BSS method has low computational complexity, so it has a faster calculation speed and is used in application scenarios with high real-time requirements. The disadvantage is that the anti-interference ability is weak because it only compensates for the phase of the signal but not the amplitude of the signal. At the same time, BSS uses interpolation and other calculation methods in the signal processing process, and large temperature differences may lead to error amplification.

[0004] Optimal baseline selection OBS method: Lu proposed an environmental compensation scheme for a benchmark database, called the optimal baseline selection (OBS). This method collects benchmark signals at a temperature interval of 0.1°C, builds a benchmark database, and imports the collected signals into the signal library for comparison to determine the health of the structure. The OBS method has a high computational complexity, and it is necessary to compare and analyze the collected signals with the signals in the benchmark database. It is suitable for application scenarios with high accuracy requirements, and the accuracy of compensation can be improved by establishing a benchmark database. Disadvantages: It is necessary to build a benchmark database, so a large amount of benchmark signal data is required; the computational complexity is high.

[0005] Therefore, it is necessary to develop a new ultrasonic detection signal compensation method to solve the above problems existing in the existing pipeline weld defect detection signal temperature compensation method. Summary of the invention

[0006] The object of the present invention is to provide a pipeline welding defect ultrasonic detection signal compensation method based on HBO to ensure the pipeline welding defect detection signal compensation effect while increasing its detection temperature range.

[0007] The technical solution of the present invention is: A pipeline welding defect ultrasonic detection signal compensation method based on HBO, characterized in that: the pipeline welding defect ultrasonic detection signal compensation method comprises the following steps: 1) Introduce analytical functions; Based on the ultrasonic detection defect signal m(t), the analytical function q(t) is introduced and can be expressed as follows: Where: H[m(t)] represents the Hilbert transform processing of the signal m(t); then the instantaneous phase and instantaneous amplitude are obtained: Where: is the instantaneous amplitude information of signal m(t); That is, it represents the instantaneous phase of the signal m(t); Given a reference signal m b (t) and the measured signal m b (t) can be expressed as: The phase change is basically linear, defined as Indicates that the collected signal is m Ti (t) is the phase compensation coefficient. Therefore, the above formula can be expressed as: m b (t) = F(t,T i )m T (p i (t)) (5).

[0008] 2) Obtain the phase / amplitude-temperature curve: According to the temperature effect (-30℃-50℃) of the ultrasonic detection signal, the phase and amplitude information are obtained by Hilbert transform, and the phase / amplitude-temperature relationship curve is derived. The phase temperature curve is fitted by linear regression, and the amplitude temperature curve is fitted by Gaussian.

[0009] 3) Obtain the phase / amplitude compensation coefficient: Define a temperature sub-interval ΔT, where there are multiple acquisition signals within ΔT Then each ΔT can be expressed as follows: in: and Temperature and The reference signal collected under and The instantaneous phase of b1 -T b2 |=ΔT. The corresponding temperature phase compensation coefficient can be obtained As shown below: The signal after phase compensation can be expressed as: m′(t)=Re(m T (t)p i (t)) (8) In measuring signal Within the ΔT, the amplitude is compensated by interpolation method, and the amplitude compensation coefficient can be expressed as: in: and Respectively, at temperature and The reference signal collected under and The instantaneous amplitude of b1 -T b2 |=ΔT.

[0010] 4) Obtain the phase / amplitude compensation coefficient: The signal after completing phase compensation and amplitude compensation for the measured signal is expressed as:

[0011] 5) Compensation of original ultrasonic detection signal under temperature change: Through steps 1) to 4), the original ultrasonic detection signal is compensated and corrected to eliminate the influence of temperature change on the defect detection signal and reduce the probability of misjudgment.

[0012] The advantages of the present invention are: This HBO-based pipeline welding defect ultrasonic detection signal compensation method proposes a strategy for building a signal compensation dictionary library, arranging the phase and amplitude compensation coefficients in each sub-interval in order, constructing a signal compensation coefficient set F, and finally establishing a temperature compensation model dictionary library under the temperature environment of the pipeline. In actual engineering applications, the measured signal m(t) is imported into the temperature compensation dictionary library, and the phase compensation coefficient at the corresponding temperature can be obtained according to the measured temperature of the signal. and amplitude compensation coefficient Ultimately, temperature compensation of ultrasonic detection signals can be achieved, the detection accuracy of pipeline welding defects can be improved, and the misjudgment rate of defects can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a specific flow chart of the present invention: Figure 2 A picture of a welded pipe test piece during the experiment of the present invention; Figure 3 Phase-temperature fitting curve diagram in the experiment; Figure 4 It is the amplitude-temperature fitting curve diagram in the experiment; Figure 5 The compensation effect of different temperature ranges at a reference temperature of 25°C; Figure 6 The compensation effect of different defects at a reference temperature of 25°C; Figure 7 Compensation effect of pore defects at different reference temperatures. DETAILED DESCRIPTION

[0014] The impact of temperature change on ultrasonic signals is essentially that the temperature effect causes changes in the performance of piezoelectric sensors and pipeline material properties, which is manifested as changes in the wave velocity and energy of signal propagation, and is reflected in the amplitude and phase changes of ultrasonic acquisition signals. Considering the changes in phase and amplitude information, when the temperature changes from T0 to Ti, the impact of temperature changes on the acquisition signal can be expressed as follows: Where: m(t) represents the ultrasonic acquisition signal, F(t,T i ) indicates that at temperature T i The amplitude variation coefficient at time t y It represents the signal delay information when the temperature changes from T0 to Ti. Assume that a fixed time window is given and F(t,T i ) and t y are defined as constant values, and the phase change caused by temperature will cause the overall displacement of the windowed signal. y Rewrite it as follows: Where: Represents the relevant time stretch coefficient. Therefore, the temperature compensation principle, that is, the expression of the influence of temperature change on the ultrasonic detection signal can be written as follows:

[0015] The compensation method for ultrasonic detection signals under temperature changes is to calculate the amplitude and phase-related compensation coefficients of ultrasonic signals under various temperature conditions. The phase and amplitude information of the ultrasonic acquisition signal is extracted, and the formula for the phase and amplitude changes with temperature is derived to obtain the compensation coefficient corresponding to the temperature. Finally, the signal is reconstructed to achieve temperature compensation of the acquisition signal and remove the influence of temperature changes on the ultrasonic signal.

[0016] This research method performs signal compensation based on HBO, which ensures the signal compensation effect while obtaining a larger temperature detection range. The specific steps are as follows: 1) Establish a temperature compensation model; Based on the ultrasonic detection defect signal m(t), the analytical function q(t) is introduced and can be expressed as follows: Where: H[m(t)] represents the Hilbert transform processing of the signal m(t). The instantaneous amplitude and instantaneous phase information of the ultrasonic signal can be calculated using the following formula: Where: is the instantaneous amplitude information of the signal m(t). That is, it represents the instantaneous phase of the signal m(t).

[0017] First, according to the temperature effect of the ultrasonic detection signal (-30℃-50℃), the phase and amplitude information are obtained by Hilbert transform, and the phase / amplitude-temperature relationship curve (formula) is derived. b (t) and the measured signal The corresponding amplitude compensation coefficient and phase compensation coefficient can be calculated. b (t) can be expressed as: Since the phase change is basically linear, the definition Indicates that the collected signal is m Ti (t) is the phase compensation coefficient. Therefore, the above formula can be expressed as: m b (t) = F(t,T i )m T (p i (t)) (8).

[0018] Since the temperature range of the collected signal is large, if only one temperature reference signal is selected, even after temperature compensation, it will not achieve a good effect. In the process of compensation, signal distortion may occur, making the signal more complex and difficult to analyze. Therefore, it is necessary to combine the reference signal expansion (BSS) and the optimal reference signal (OBS), define equidistant temperature sub-intervals, select the corresponding reference signal in each interval, and build a reference signal library.

[0019] According to the temperature effect of ultrasonic detection signal (-30℃-50℃), the phase-temperature relationship curve (formula) is derived. Based on the fitting formula, the phase interpolation compensation is performed and a temperature sub-interval ΔT is defined, where there are multiple acquisition signals within ΔT. Then each ΔT can be expressed as follows: Where: and Temperature and The reference signal collected under and The instantaneous phase (where: |T b1 -T b2 |=ΔT). The corresponding temperature phase compensation coefficient can be obtained As shown below: The signal after phase compensation can be expressed as: m′(t)=Re(m T (t)p i (t)) (11).

[0020] The amplitude-temperature relationship curve is derived. Based on the discontinuity of the detection signal, in order to accurately compensate for the ultrasonic signal outside the signal acquisition point, the entire temperature range is also divided into multiple sub-ranges ΔT. Within the ΔT, the amplitude is compensated by interpolation method, and the amplitude compensation coefficient can be expressed as: Where: and Respectively, at temperature and The reference signal collected under and The instantaneous amplitude (where: |T b1 -T b2 |=ΔT).

[0021] The signal after completing phase compensation and amplitude compensation for the measured signal can be expressed as: This research method proposes a strategy for constructing a signal compensation dictionary library, arranging the phase and amplitude compensation coefficients in each sub-interval in order, constructing a signal compensation coefficient set F, and finally establishing a temperature compensation model dictionary library under the temperature environment of the pipeline. In actual engineering applications, the measured signal m(t) is imported into the temperature compensation dictionary library, and the phase compensation coefficient at the corresponding temperature can be obtained according to the measured temperature of the signal. and amplitude compensation coefficient Ultimately, temperature compensation of ultrasonic detection signals can be achieved, the detection accuracy of pipeline welding defects can be improved, and the misjudgment rate of defects can be reduced.

[0022] In order to verify the correctness of this application, the applicant conducted the following experiments: The time parameters of the selected test samples 3A, 3B, 3C, and 3D are shown in Table 1. The amount of ultrasonic detection signal collection for weld defects is shown in Table 2. The weld pipe specimens are shown in Table 2. Figure 2 .

[0023] Table 1 Design of welding defect pipeline specimen Based on the HBO compensation method, a temperature sub-interval ΔT is defined to compensate and correct the ultrasonic detection signals (signals after denoising) of the four defects. The fitting effect of the curve can be evaluated by the determination coefficient (R2), which is determined by the sum of squares of the difference between the predicted data and the original data mean (SSR) and the sum of squares of the difference between the original data and the mean (SST). The calculation formula is as follows: Among them, R2 characterizes the curve fitting effect through the change characteristics of the data. According to the above formula, the value range of R2 is [0,1]. The closer its value is to 1, the stronger the ability of the curve fitting variable to explain y, that is, the better the fitting effect of the data.

[0024] Table 2 Ultrasonic detection data volume of pipeline weld defects Test piece number defect Defect Number length Number of data 3A Unfused F1 30 160 3A Unfused F2 25 162 3A Unfused F3 20 159 3A Unfused F4 10 151 3B Pores P1 10 162 3B Pores P2 20 153 3B Pores P3 25 157 3B Pores P4 30 160 3C crack W1 10 156 3C crack W2 20 160 3C crack W3 25 156 3C crack W4 30 160 3D Slag inclusion S1 30 158 3D Slag inclusion S2 25 161 3D Slag inclusion S3 20 155 3D Slag inclusion S4 10 158 Based on this, the instantaneous phase of the detection signal of the unfused, crack, pore and slag defect is obtained. Since the phase changes with the temperature basically presents a linear relationship, the relationship between the phase of the four defect signals and the temperature (-30℃-50℃) is linearly fitted. The results are as follows: Figure 3As shown. It can be seen that the R2 of the phase-temperature fitting curves of the unfused, crack, pore and slag defects are 0.996, 0.994, 0.993 and 0.990 respectively, all of which are kept above 0.99, indicating that the phase-temperature fitting curves of the four defect signals have a high degree of fit with the phase of the measured signal. At the same time, the phase-temperature fitting formulas of different defects are obtained, which provides a model basis for the phase compensation of defect signals at non-detection points within ΔT.

[0025] In statistics and data analysis, regression analysis is a commonly used method to study the relationship between independent variables and dependent variables. The regression equation is the core of regression analysis, which describes the mathematical relationship between independent variables and dependent variables. In this study, since the amplitude-temperature relationship of the ultrasonic detection signal is not linear, we will use the GaussAmp method to fit the amplitude-temperature regression equation. The GaussAmp method has strong flexibility in fitting curves and can be applied to various types of data and problems. At the same time, due to the characteristics of the Gaussian function, this method can provide higher fitting accuracy. The Gaussian function can be expressed by the following formula: Where: A is the amplitude of the Gaussian function, xc is the center position of the Gaussian function, and w is the standard deviation of the Gaussian function. The GaussAmp method finds the best regression equation by fitting these parameters.

[0026] The signal amplitude and temperature relationship of four defects (lack of fusion, slag inclusion, pores and cracks) were fitted by multiple iterations of Gaussian function. The results are as follows Figure 4 As shown. The R2 of the four defects are 0.997, 0.995, 0.996 and 0.993, respectively, all of which remain above 0.993, indicating that the amplitude-temperature fitting curves of the four defect signals have a high degree of fit with the amplitude information of the measured signal. At the same time, the amplitude-temperature fitting formulas of different defects are obtained, which provides a model basis for the signal amplitude compensation of non-detection points within ΔT.

[0027] In order to verify the impact of this application on the ultrasonic signal compensation temperature range, compensation of different types of defect signals and compensation of different reference temperature signals, the applicant conducted the following analysis: 1) Ultrasonic signal compensation temperature range: In order to ensure a better compensation effect of the ultrasonic detection signal, it has a maximum compensation temperature range.

[0028] Based on the HBO method, the temperature compensation of the signal is performed to obtain the maximum temperature sub-interval ΔT within the allowable error. The signal of the pore defect after ENL denoising is selected as the compensated signal. The reference signal is 25℃, and the signals with temperature sub-intervals of 8℃, 9℃, 10℃, and 11℃ are compensated. The compensation results are shown in the figure. Figure 5As shown, it can be seen that when the temperature range is 11°C, the amplitude and phase of the compensation signal are significantly different from those of the reference signal, and the compensation effect is poor. Otherwise, the compensation effect is good.

[0029] For the compensation effect of ultrasonic signals, MSE is also selected as the evaluation indicator because the goal is to compensate the ultrasonic waveform as accurately as possible and reduce the difference between the compensated waveform and the actual target waveform. Therefore, it is hoped that the model can minimize the error, and MSE can help us identify and optimize possible problem points in the model by imposing a greater penalty on larger errors, thereby improving the accuracy and reliability of the model. Therefore, MSE becomes an ideal choice for measuring the performance of ultrasonic waveform compensation models.

[0030] For the denoised signal, the subsequent compensation is mainly for the phase and amplitude of the defect reflection signal. Therefore, it is necessary to first define the signal interval for calculating the MSE. This interval should at least include the complete defect reflection waveform area. The MSE calculation interval setting is shown as follows: Figure 5 (d) is shown. The MSE value of the defect reflection waveform compensation signal in each temperature sub-interval is calculated separately, as shown in Table 3. When the temperature compensation range is 11°C, the compensation effect analyzed in the previous article is significantly reduced, and the phase and amplitude show obvious differences, and the MSE reaches 2.000. Therefore, in order to facilitate calculation and subsequent comparative analysis, this study intends to select 10°C as the temperature sub-interval ΔT for pipeline weld defect signal compensation, and define the threshold of the compensation signal MSE as 2.000, that is, when the compensation signal of the weld defect reflection waveform and the reference signal MSE are less than 2.000, it is considered that a relatively stable signal compensation can be achieved.

[0031] Table 3 Model compensation effect of different temperature sub-intervals (ΔT) Temperature interval length ΔT(℃) MSE 8 1.864 9 1.895 10 1.924 11 2.000 The HBO compensation method can realize the temperature compensation of ultrasonic detection signals of pipeline weld defects. The phase and amplitude-temperature curves of the defects of lack of fusion, cracks, pores and slag inclusions are fitted. According to the temperature compensation sub-interval ΔT, the MSE threshold can be selected as 2.000, and the phase and amplitude of the signal can be compensated and corrected using this model. The results show that the MSE is lower than 2.000. The temperature compensation model has a certain applicability for the compensation of pipeline weld defect signals. The reference signal expansion (BSS) uses interpolation and other calculation methods in the signal processing process, but the large temperature difference may lead to error amplification; the optimal reference selection (OBS) requires a large number of reference signals to achieve accurate temperature compensation.

[0032] 2) Compensation for different types of defect signals: In order to verify that the HBO compensation method can be applied to various types of weld defects, this study compensated for the signals of unfused, cracked, pore and slag inclusion defects (see Table 4-1) at a reference temperature of 25°C (ΔT is 20-30°C). To facilitate the analysis of the compensation effect, the signal was selected as the signal after ENL model denoising (denoised signal). The results are shown in the figure below. Figure 6 As shown, it can be seen that the phase and amplitude of the original signal have been corrected and compensated. There are slight differences between the phase and amplitude compensation of some ultrasonic detection signals and the reference signal. This is because the waveform characteristics of the ultrasonic signal change at different temperatures. The MSE value of the compensation signal in the defect reflection signal area and the reference signal can be calculated to determine whether the temperature compensation of the signal meets the compensation effect of this study.

[0033] The MSE values ​​of the compensation signals are calculated respectively, and the results are shown in Table 4. It can be seen that the MSE values ​​of the compensation signal and the reference signal in the defect reflection area are both less than 1.952, and the errors between the compensation signal and the reference signal are small. The slight differences in phase and amplitude compensation do not affect the compensation effect of the defect reflection signal. Therefore, it is shown that the HBO compensation method has good applicability for the compensation of ultrasonic detection signals of different defect types.

[0034] Table 4 Model compensation effects of different defect types at 25℃ reference temperature Defect Type MSE Unfused 1.927 Pores 1.924 crack 1.941 Slag inclusion 1.952 3) Compensation for different reference temperature signals: In order to verify that the HBO compensation method can be applied to the ultrasonic detection signal compensation of pipeline weld defects under various ambient temperatures, this study selected 0℃, 25℃ (see Figure 6 ), -20℃, 40℃ are used as reference signals for compensation, and the temperature sub-interval ΔT is 10℃. The results are as follows Figure 7 As shown, it can be seen that the phase and amplitude of the denoised signal have achieved correction compensation with the reference signal, and the consistency is good.

[0035] The MSE of the compensation signal and the reference signal are calculated, as shown in Table 5. It can be seen that the MSE is no higher than 1.979, and the error between the compensation signal and the reference signal is small, which shows that the model can realize signal compensation at different reference temperatures for ultrasonic detection signals of pipeline weld defects, and the effect and applicability are good, but there is a limit to the signal compensation temperature range.

[0036] Table 5 Model compensation effect of pore defects at different reference temperatures Reference temperature (℃) MSE 25 1.924 0 1.935 -20 1.979 40 1.920 The present invention obtains the phase and amplitude information of the signal based on Hilbert transform to reduce the generation of errors. In combination with BSS and OBS, a pipeline welding defect ultrasonic detection signal compensation method based on HBO is proposed to ensure the pipeline welding defect detection signal compensation effect while increasing its detection temperature range.

[0037] This HBO-based pipeline welding defect ultrasonic detection signal compensation method proposes a strategy for building a signal compensation dictionary library, arranging the phase and amplitude compensation coefficients in each sub-interval in order, constructing a signal compensation coefficient set F, and finally establishing a temperature compensation model dictionary library under the temperature environment of the pipeline. In actual engineering applications, the measured signal m(t) is imported into the temperature compensation dictionary library, and the phase compensation coefficient at the corresponding temperature can be obtained according to the measured temperature of the signal. and amplitude compensation coefficient Ultimately, temperature compensation of ultrasonic detection signals can be achieved, the detection accuracy of pipeline welding defects can be improved, and the misjudgment rate of defects can be reduced.

Claims

1. A pipeline welding defect ultrasonic detection signal compensation method based on HBO, characterized by: The pipeline welding defect ultrasonic detection signal compensation method comprises the following steps: 1) Introduce analytical functions; 2) Obtain the phase / amplitude-temperature curve: According to the temperature effect of ultrasonic detection signal, Hilbert transform is used to obtain phase and amplitude information, and the phase / amplitude-temperature relationship curve is derived. The phase temperature curve is fitted by linear regression, and the amplitude temperature curve is fitted by Gaussian. 3) Obtain the phase / amplitude compensation coefficient: Define a temperature sub-interval ΔT, where there are multiple acquisition signals within ΔT Then each ΔT can be expressed as follows: in: and Temperature and The reference signal collected under and The instantaneous phase of |T b1 -T b2 |=ΔT; The corresponding temperature phase compensation coefficient can be obtained As shown below: The signal after phase compensation can be expressed as: m′(t)=Re(m T (t)p i (t)) (8) In measuring signal Within the ΔT, the amplitude is compensated by interpolation method, and the amplitude compensation coefficient can be expressed as: in: and Respectively, at temperature and The reference signal collected under and The instantaneous amplitude of 4) Obtain the phase / amplitude compensation coefficient: The signal after completing phase compensation and amplitude compensation for the measured signal is expressed as: 5) Compensation of original ultrasonic detection signal under temperature change: Through steps 1) to 4), the original ultrasonic detection signal is compensated and corrected to eliminate the influence of temperature change on the defect detection signal and reduce the probability of misjudgment.

2. The method for compensating pipeline welding defect ultrasonic detection signals based on HBO according to claim 1, characterized in that: The temperature effect of the ultrasonic detection signal ranges from -30°C to 50°C.

3. The method for compensating pipeline welding defect ultrasonic detection signals based on HBO according to claim 1, characterized in that: The step 1) introduces the analytical function, comprising the following steps: Based on the ultrasonic detection defect signal m(t), the analytical function q(t) is introduced and can be expressed as follows: Where: H[m(t)] represents the Hilbert transform of the signal m(t); then the instantaneous phase and instantaneous amplitude are obtained: Where: is the instantaneous amplitude information of signal m(t); That is, it represents the instantaneous phase of the signal m(t); Given a reference signal m b (t) and the measured signal m Ti (t), m b (t) can be expressed as: The phase change is basically linear, defined as Indicates that the collected signal is m Ti Phase compensation coefficient at time (t); Therefore, the above formula can be expressed as: m b (t)=F(t,T i )m T (p i (t)) (5)。

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