Concrete slab crack damage imaging positioning method and system based on Lamb waves

Abstract

The invention discloses a Lamb wave-based concrete slab crack damage imaging positioning method and system. The method comprises the following steps: acquiring a lossless signal and a lossy signal transmitted by a concrete slab; calculating a correlation coefficient damage factor and an amplitude difference damage factor, and obtaining a crack damage factor of each propagation path; performing preliminary imaging according to the crack damage factor; extracting the maximum values of the damage factors of the correlation coefficients in the propagation path passing through the initial damage area, comparing the maximum values to obtain a parallel path of the crack, and correcting the crack damage factors of the parallel path to obtain a final crack damage factor; and carrying out visual imaging on the final crack damage factor to obtain the damage information of the concrete slab crack. According to the invention, the visual imaging and accurate positioning of the crack damage can be realized, and the position and shape information of the crack can be accurately reflected.

Description

Technical Field

[0001] The present invention relates to the technical field of crack damage detection for concrete structures, and particularly to a method and system for imaging and positioning crack damage of concrete slabs based on Lamb waves. Background Art

[0002] Concrete is widely used in civil engineering construction due to its high strength, good durability and other characteristics. However, during long-term use, it is prone to crack damage, which seriously threatens the safety and reliability of the structure. As an early manifestation of structural damage, cracks can be detected in a timely and accurate manner, and corresponding reinforcement and repair measures can be taken to effectively prevent structural failure and avoid adverse consequences caused by structural damage. Therefore, there is an urgent need in this field for an efficient and accurate method for imaging and positioning crack damage of concrete slabs.

[0003] Commonly used means for crack detection of concrete slabs in the prior art include fiber Bragg grating technology, acoustic emission technology, piezoresistive impedance technology, active Lamb wave technology, and so on. Among them, the active Lamb wave detection technology has shown significant advantages in structural health monitoring due to its characteristics such as long propagation distance, high sensitivity, fast response speed, low attenuation, and being less susceptible to external environmental factors. By analyzing the propagation characteristics of Lamb waves in the structure and exploring the influence mechanism of crack damage on Lamb waves, the relationship between the two can be established to identify the location and shape of the damage.

[0004] However, it is found in the research that when using the Lamb wave detection technology for crack damage detection, the existing methods have problems such as difficulties in signal processing and data analysis, large computational amount, insufficient detection accuracy and sensitivity. At the same time, the research on crack visualization imaging technology is relatively less, making it difficult to be truly applied to actual engineering projects. And in the calculation method of the damage factor in the existing patents, it is difficult to simultaneously reflect the differences in amplitude and phase between the non-damaged signal and the damaged signal, and thus it is impossible to accurately reflect the signal characteristics of crack damage. Moreover, there is a lack of correction for the damage factor in the existing technology, which will make it difficult to reflect the damage information due to the small signal difference in parallel paths, thereby affecting the accuracy of crack imaging. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention provides a method and system for imaging and positioning crack damage of concrete slabs based on Lamb waves, which can realize the visual imaging and precise positioning of crack damage and accurately reflect the position and shape information of the cracks.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a method for imaging and positioning crack damage of concrete slabs based on Lamb waves, including:

[0008] Obtain the non-destructive signal and the destructive signal after propagation through the concrete slab;

[0009] According to the non-destructive signal and the destructive signal, calculate the correlation coefficient damage factor and the amplitude difference damage factor of each propagation path, and obtain the crack damage factor of each propagation path through weighting;

[0010] Perform preliminary imaging based on the crack damage factor of each propagation path to determine the initial damage area;

[0011] Extract the maximum value of the correlation coefficient damage factor in the propagation paths passing through the initial damage area for comparison to obtain the parallel paths of the crack, and correct the crack damage factor of the parallel paths to obtain the final crack damage factor;

[0012] Visualize the final crack damage factor to obtain the damage information of the cracks in the concrete slab.

[0013] As a further technical solution, in the ventricular finite element model, the method for collecting the non-destructive signal and the destructive signal of the concrete slab is as follows: First, arrange an annular sensor array on the surface of the concrete slab. The sensor array consists of multiple sensors numbered in sequence, which are used to excite the Lamb wave signal and receive the propagated signal; then, sequentially use one sensor as the exciter to release the Lamb wave signal, and the subsequent numbered sensors as the receivers to receive the signal propagated through the concrete slab, so as to collect the non-destructive signal and the destructive signal respectively.

[0014] As a further technical solution, the calculation method of the correlation coefficient damage factor is:

[0015] where i is the exciter number, j is the receiver number, x ij (t), y ij (t) are the amplitudes of the non-destructive signal and the destructive signal respectively, t0 is the direct arrival time of the excitation signal on each propagation path Figure 1 , u x , u y are the average values of the non-destructive signal and the destructive signal respectively, and ΔT is a time window.

[0016] As a further technical solution, the calculation method of the amplitude difference damage factor is:

[0017] where x k is the amplitude of the non-destructive signal corresponding to the k-th time interval, and y k is the amplitude of the destructive signal corresponding to the k-th time interval.

[0018] As a further technical solution, the calculation formula for obtaining the crack damage factor of each propagation path by weighting is as follows:

[0019] After obtaining the parallel paths of the cracks, the crack damage factor of the parallel paths is corrected to 1 to obtain the final crack damage factor.

[0020] As a further technical solution, after obtaining the crack damage factor of each propagation path, the damage probability detection reconstruction algorithm is used to calculate the damage probability of each pixel point for the preliminary imaging of the damaged area and determine the initial damaged area.

[0021] As a further technical solution, the specific method for obtaining the parallel paths of the cracks is as follows: count the propagation paths passing through the initial damaged area and group them according to the numbers of the exciters; remove the damage propagation paths of the groups containing duplicate numbers to obtain the damage groups; extract and compare the maximum values of the correlation coefficient damage factors in the damage groups, and the path corresponding to the minimum value among them is the parallel path of the crack.

[0022] In a second aspect, the present invention provides a crack damage imaging and positioning system for a concrete slab based on Lamb waves, including the following modules:

[0023] A signal acquisition module, configured to: acquire the non-destructive signal and the destructive signal propagated through the concrete slab;

[0024] A damage factor calculation module, configured to: calculate the correlation coefficient damage factor and the amplitude difference damage factor of each propagation path according to the non-destructive signal and the destructive signal, and obtain the crack damage factor of each propagation path by weighting;

[0025] A damaged area determination module, configured to: perform preliminary imaging according to the crack damage factor of each propagation path and determine the initial damaged area;

[0026] A parallel path and final crack damage factor determination module, configured to: extract and compare the maximum values of the correlation coefficient damage factors in the propagation paths passing through the initial damaged area to obtain the parallel paths of the cracks, and correct the crack damage factor of the parallel paths to obtain the final crack damage factor;

[0027] An imaging module, configured to: perform visual imaging on the final crack damage factor to obtain the damage information of the cracks in the concrete slab.

[0028] One or more technical solutions of the present invention have the following beneficial effects:

[0029] (1) The present invention proposes a new calculation method for damage factors, which can simultaneously reflect the differences in amplitude and phase between the non-damaged signal and the damaged signal, more accurately reflect the signal characteristics of crack damage, and greatly improve the detection accuracy.

[0030] (2) The present invention extracts the maximum value of the correlation coefficient damage factor in the propagation path passing through the initial damage area for comparison to obtain the parallel paths of the crack, and corrects the crack damage factors of the parallel paths, effectively solving the problem that it is difficult to reflect the damage information due to the small signal differences in the parallel paths, and improving the accuracy of crack imaging.

[0031] (3) The present invention combines the damage probability detection reconstruction algorithm to achieve the positioning and visualization imaging of crack damage, and can clearly display the position and shape of the crack, providing strong support for the damage assessment and maintenance of concrete structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings forming a part of this invention are used to provide a further understanding of the invention. The schematic embodiments and descriptions thereof of the invention are used to explain the invention and do not constitute an improper limitation of the invention.

[0033] Figure 2 is a schematic diagram of the overall process of the method and system for positioning and imaging crack damage in concrete slabs according to the present invention;

[0034] Figure 3 is a schematic diagram of the sensor array layout according to the present invention;

[0035] Figure 4 is a schematic diagram of the damage probability detection reconstruction algorithm adopted by the present invention;

[0036] Figure 5 is a diagram of the crack damage detection imaging result in the simulation according to the present invention;

[0037] Figure 1 is a diagram of the crack damage detection imaging result in the experiment according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0039] Embodiment 1

[0040] In this embodiment, a method for imaging and positioning crack damage in a concrete slab based on Lamb waves is provided. As Figure 2 shown, the specific method steps are as follows:

[0041] Step 1: Obtain the non-destructive signal and the destructive signal after propagation through the concrete slab;

[0042] Step 2: According to the non-destructive signal and the destructive signal, calculate the correlation coefficient damage factor and the amplitude difference damage factor of each propagation path, and obtain the crack damage factor of each propagation path through weighting;

[0043] Step 3: Conduct preliminary imaging based on the crack damage factor of each propagation path to determine the initial damage area;

[0044] Step 4: Extract the maximum value of the correlation coefficient damage factor in the propagation paths passing through the initial damage area for comparison to obtain the parallel paths of the crack, and correct the crack damage factor of the parallel paths to obtain the final crack damage factor;

[0045] Step 5: Visualize the final crack damage factor to obtain the damage information of the concrete slab crack, and the damage information includes the shape and size information of the crack.

[0046] In Step 1, the method for collecting the non-destructive signal and the destructive signal of the concrete slab is as follows: First, arrange a circular sensor array on the surface of the concrete slab to form a relatively dense detection network. The sensor array consists of multiple sensors numbered in sequence, which are used to excite the Lamb wave signal and receive the propagated signal. In a specific embodiment, the specific arrangement is as Figure 3 shown. The sensor array consists of 12 sensors of model PZT5, the diameter of the array is 300 mm, and it is pasted on the surface of the concrete slab. The size of the concrete slab is 600 mm×600 mm×20 mm.

[0047] Then, sequentially use one sensor as the exciter to release the Lamb wave signal, and the subsequent numbered sensors as the receivers to receive the signal propagated through the concrete slab, so as to collect the non-destructive signal and the destructive signal respectively. In a specific embodiment, sequentially use the sensor as the exciter to release the Lamb wave signal with a center frequency of 70 kHz, and the subsequent numbered sensors as the receivers to receive the signal propagated through the concrete slab. The Lamb signals of the concrete slab under non-destructive conditions and crack damage conditions are collected through simulation and experiment respectively, which are the non-destructive signal and the destructive signal respectively.

[0048] In Step 2, the definition of the correlation coefficient damage factor of each propagation path is:

[0049] where i is the exciter number, j is the receiver number, x ij (t), y ij (t) are the amplitudes of the non-destructive signal and the destructive signal respectively, t0 is the direct arrival time of the excitation signal on each propagation path, u x , u yThey are the average values of the lossless signal and the lossy signal respectively, and ΔT is a time window. DI ij ranges from [0, 1], which reflects the size of the corresponding path damage probability. When its value is 1, it indicates serious damage, and when its value is 0, it indicates no damage.

[0050] The definition of the amplitude difference damage factor for each propagation path is:

[0051] where x k is the amplitude of the lossless signal corresponding to the k-th time interval, y k is the amplitude of the lossy signal corresponding to the k-th time interval, and n represents the number of signals.

[0052] In step 2, the propagation characteristics of Lamb waves in concrete slabs and the influence of crack damage on guided waves are studied, and a new definition of the crack damage factor is proposed: the crack damage factor of each propagation path is obtained by weighting, and it is specifically expressed as:

[0053] In step 3, preliminary imaging is performed according to the crack damage factor of each propagation path. Specifically: the crack damage factor is calculated and used in the damage probability detection reconstruction algorithm. Its basic principle is as Figure 4 shown. The damage probability of each pixel is calculated based on the crack damage factor calculated from the signals of each propagation path, which is used for the preliminary imaging of the damaged area to lock a larger range of damaged areas, that is, to determine the initial damaged area.

[0054] In step 4, the parallel path extraction method for crack parallel paths is used to find the parallel paths of the crack. Specifically: the propagation paths passing through the initial damaged area are counted and grouped according to the number of the actuator; the propagation paths of the groups containing duplicate numbers are removed to obtain the damaged groups; the maximum values of the correlation coefficient damage factors in the damaged groups are extracted and compared, and the path corresponding to the minimum value among them is the parallel path of the crack. In this embodiment, the propagation paths passing through the initial damaged area are counted as 6 groups, which are: S1 - S6, S1 - S7, S1 - S8; S2 - S8, S2 - S9, S2 - S10; S3 - S9, S3 - S10, S3 - S11; S4 - S10, S4 - S11, S4 - S12; S5 - S11, S5 - S12; S6 - S12. Since there is a duplicate item number 6 between S1 - S6 and S6 - S12, the damaged paths of the 6 groups are removed. The maximum values of DI for groups 1 - 5 are compared, and the DI value of group 3 is the minimum among groups 1 - 5, and its corresponding damage propagation path is S3 - S11, that is, the parallel path of the crack damage is S3 - S11. In another implementation, the damage propagation path of the crack is S1 - S5; in yet another implementation, the damage propagation path of the crack is S1 - S9.

[0055] In step 4, after obtaining the parallel paths of the cracks, the crack damage factor of the parallel paths is corrected to 1 to obtain the final crack damage factor, and the final crack damage factor is defined as:

[0056]

[0057] where a and b are the numbers of the parallel path exciters and receivers respectively, and the value range of CDF ij is [0, 1], and the calculated normalized data can reflect the damage probability information of the corresponding path. It has been verified to be effective through subsequent simulations and experiments.

[0058] Respectively correct the crack damage factors of different parallel paths, correct them to 1 to obtain the final crack damage factor, and combine the final crack damage factor with the damage probability detection reconstruction algorithm to realize the positioning and imaging of crack damage. The imaging results are as Figure 5 shown.

[0059] At the same time, to verify the robustness of the proposed crack positioning and imaging method, an experimental example was implemented. The same concrete slab as in the simulation was still used for the experiment, and the same processing steps as above were adopted. The obtained experimental results are as ​ shown, verifying that the method has good robustness and can be applied to the actual detection of single crack damage.

[0060] Embodiment 2

[0061] In this embodiment, a crack damage imaging and positioning system for a concrete slab based on Lamb waves is provided, including the following modules:

[0062] A signal acquisition module, configured to: acquire the non-destructive signal and the damaged signal after propagation through the concrete slab;

[0063] A damage factor calculation module, configured to: calculate the correlation coefficient damage factor and the amplitude difference damage factor of each propagation path according to the non-destructive signal and the damaged signal, and obtain the crack damage factor of each propagation path through weighting;

[0064] A damage area determination module, configured to: perform preliminary imaging according to the crack damage factor of each propagation path to determine the initial damage area;

[0065] A parallel path and final crack damage factor determination module, configured to: extract the maximum value of the correlation coefficient damage factor in the propagation paths passing through the initial damage area for comparison to obtain the parallel paths of the cracks, and correct the crack damage factor of the parallel paths to obtain the final crack damage factor;

[0066] The imaging module is configured to: perform visual imaging on the final crack damage factor to obtain the damage information of the concrete slab cracks.

[0067] For those skilled in the art, various changes and modifications can be made to the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for imaging and locating crack damage of a concrete slab based on Lamb waves, characterized in that Including: Obtaining the non-destructive signal and the destructive signal after propagation through the concrete slab; Calculating the correlation coefficient damage factor and the amplitude difference damage factor of each propagation path according to the non-destructive signal and the destructive signal, and obtaining the crack damage factor of each propagation path through weighting; Performing preliminary imaging according to the crack damage factor of each propagation path to determine the initial damage area; Extracting the maximum value of the correlation coefficient damage factor in the propagation paths passing through the initial damage area for comparison to obtain the parallel paths of the crack, and correcting the crack damage factor of the parallel paths to obtain the final crack damage factor; Performing visual imaging on the final crack damage factor to obtain the damage information of the concrete slab crack.

2. The method for imaging and positioning the crack damage of a concrete slab based on Lamb waves according to claim 1, wherein The method for collecting the non-destructive signal and the destructive signal of the concrete slab is as follows: First, arrange a circular sensor array on the surface of the concrete slab. The sensor array consists of multiple sensors numbered in sequence, which is used to excite the Lamb wave signal and receive the propagated signal; then, sequentially use one sensor as the exciter to release the Lamb wave signal, and the subsequent numbered sensors as the receivers to receive the signal propagated through the concrete slab, so as to collect the non-destructive signal and the destructive signal respectively.

3. A method for imaging and positioning crack damage of a concrete slab based on Lamb waves as claimed in claim 1, characterized in that, The calculation method of the correlation coefficient damage factor is: Among them, i is the actuator number, j is the receiver number, x ij (t), y ij (t) are the amplitudes of the lossless signal and the lossy signal respectively, t0 is the direct arrival time of the excitation signal on each propagation path , u x , u y are the averages of the lossless signal and the lossy signal respectively, and ΔT is a time window.

4. The method for imaging and positioning cracks and damages of a concrete slab based on Lamb waves according to claim 1, characterized in that, The calculation method of the amplitude difference damage factor is: where x k is the amplitude of the lossless signal corresponding to the k-th time interval, and y k is the amplitude of the lossy signal corresponding to the k-th time interval.

5. The method for imaging and positioning cracks and damages of a concrete slab based on Lamb waves according to claim 1, wherein The calculation formula for obtaining the crack damage factor of each propagation path through weighting is as follows: After obtaining the parallel paths of the crack, correct the crack damage factor of the parallel paths to 1 to obtain the final crack damage factor.

6. The method for imaging and positioning cracks and damages of a concrete slab based on Lamb waves according to claim 1, wherein, After obtaining the crack damage factor of each propagation path, use the damage probability detection reconstruction algorithm to calculate the damage probability of each pixel point for the preliminary imaging of the damage area to determine the initial damage area.

7. A method for imaging and positioning cracks and damages of a concrete slab based on Lamb waves according to claim 1, characterized in that, The specific method for obtaining the parallel paths of the crack is as follows: Count the propagation paths passing through the initial damage area, and group them according to the number of the exciter; Remove the damage propagation paths of the groups containing duplicate numbers to obtain the damage groups; Extract the maximum value of the correlation coefficient damage factor in the damage groups for comparison, and the path corresponding to the minimum value among them is the parallel path of the crack.

8. A crack damage imaging and positioning system for concrete slabs based on Lamb waves, characterized in that, Including the following modules: A signal acquisition module, configured to: Obtain the non-destructive signal and the destructive signal after propagation through the concrete slab; A damage factor calculation module, configured to: Calculate the correlation coefficient damage factor and the amplitude difference damage factor of each propagation path according to the non-destructive signal and the destructive signal, and obtain the crack damage factor of each propagation path through weighting; A damage area determination module, configured to: Perform preliminary imaging according to the crack damage factor of each propagation path to determine the initial damage area; A parallel path and final crack damage factor determination module, configured to: Extract the maximum value of the correlation coefficient damage factor in the propagation paths passing through the initial damage area for comparison to obtain the parallel paths of the crack, and correct the crack damage factor of the parallel paths to obtain the final crack damage factor; An imaging module, configured to: Perform visual imaging on the final crack damage factor to obtain the damage information of the concrete slab crack.

9. A computer-readable storage medium having a program stored thereon, characterized in that, When the program is executed by a processor, it implements the steps in a method for imaging and locating the crack damage of a concrete slab based on Lamb waves as described in any one of claims 1-7.

10. An electronic device, comprising a memory, a processor, and a program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in a method for imaging and locating crack damage of a concrete slab based on Lamb waves as described in any one of claims 1-7.

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