Ultrasonic guided wave detection system and method for damage of semi-exposed wooden column of historic building

Abstract

The invention provides an ancient building semi-exposed wooden column damage ultrasonic guided wave detection system and method, the detection system comprises a hardware system and a software system, the hardware system comprises a computer, a data acquisition card, a power amplifier, an excitation end ceramic piezoelectric plate, a receiving end ceramic piezoelectric plate, a signal conditioning module and a direct current power supply; the software system comprises an excitation module, an acquisition module, a data processing module and a detection template. The excitation end ceramic piezoelectric plate is adhered to the middle of the half-exposed wooden column, and the receiving end ceramic piezoelectric plates are adhered to the top and the bottom; an ultrasonic guided wave excitation signal is generated by the data acquisition card, is amplified by the power amplifier, is transmitted to the excitation end ceramic piezoelectric plate, is transmitted to the receiving end ceramic piezoelectric plate through the semi-exposed wooden column, and is used for damage detection of the semi-exposed wooden column by a software system. According to the method, the damage detection of the semi-exposed wooden column of the historic building can be realized losslessly and quickly, the damage degree of the semi-exposed wooden column of the historic building can be accurately judged, and powerful support is provided for historic building protection.

Description

Technical Field

[0001] The present invention relates to the technical field of inspection of ancient building wooden structures, and specifically relates to a damage detection system and method for semi-exposed wooden columns of ancient buildings based on ultrasonic guided waves. Background Art

[0002] There are a large number of ancient wooden buildings in China, which are important carriers of history and culture. Ancient building wooden columns are divided into exposed columns, semi-exposed columns, and hidden columns in the wall. In northern ancient wooden buildings, the number of semi-exposed columns accounts for more than half of the total number of wooden columns. Part of the semi-exposed wooden column is hidden in the wall, the humidity at the contact part with the wall is high, and damage defects such as decay and material loss are likely to occur in the hidden part. It is difficult to be discovered, seriously affecting the safety of the entire building. However, existing non-destructive defect detection methods for ancient building wooden components, such as appearance inspection method, moisture content inspection method, micro-drilling resistance method, and stress wave detection method, etc., have problems such as low detection efficiency, complex operation, or damage to wooden components. For example, micro-drilling resistance detection requires micro-drilling along different directions on multiple cross-sections of the wooden column, which is time-consuming and laborious. Therefore, there is an urgent need for an efficient, convenient and non-destructive detection method to achieve convenient non-destructive detection of damage to semi-exposed wooden columns of ancient buildings.

[0003] Ultrasonic guided wave is a form of ultrasonic wave propagation in an elastic medium with boundary constraints (such as structures like plates, rods, tubes, etc.). It is a specific propagation mode formed by the interaction between ultrasonic waves and the structure boundary during propagation, resulting in continuous reflection and interference of waves between the boundaries. The present invention focuses on using the flexural mode wave (F wave) of ultrasonic guided waves in wooden columns for inspection, and judges the damage condition of wooden columns according to the change of its characteristic value. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a damage ultrasonic guided wave detection system and method for semi-exposed wooden columns of ancient buildings.

[0005] In the first aspect, an embodiment of the present invention provides a damage ultrasonic guided wave detection system for semi-exposed wooden columns of ancient buildings, including: a damage ultrasonic guided wave detection system for semi-exposed wooden columns of ancient buildings, the system includes a hardware system and a software system, and the hardware system includes a computer, a data acquisition card, a power amplifier, an excitation end ceramic piezoelectric sheet, a receiving end ceramic piezoelectric sheet, a signal conditioning module, and a DC power supply;

[0006] The computer is connected to the data acquisition card and is used for controlling the production, acquisition and data processing of signals;

[0007] The data acquisition card is used for generating ultrasonic guided wave excitation signals and acquiring ultrasonic guided wave signals propagated through the semi-exposed wooden column;

[0008] The power amplifier is connected to the data acquisition card and is used for amplifying the excitation signal;

[0009] The excitation-end ceramic piezoelectric sheet is pasted in the middle of the outer side of the semi-exposed wooden column and is used to convert the amplified excitation signal into an ultrasonic guided wave and input it into the semi-exposed wooden column;

[0010] The receiving-end ceramic piezoelectric sheets are pasted on the top and bottom of the outer side of the semi-exposed wooden column and are used to receive the ultrasonic guided wave signals propagating in the semi-exposed wooden column;

[0011] The signal conditioning module is connected to the receiving-end ceramic piezoelectric sheets and is used to perform high-pass filtering on the received guided wave signals;

[0012] The DC power supply supplies power to the hardware of the signal conditioning module;

[0013] The software system includes an excitation module, an acquisition module, a data processing module, and a detection template;

[0014] The excitation module controls the data acquisition card to generate an excitation signal with a specific frequency;

[0015] The acquisition module collects in real time the ultrasonic guided wave signals of the receiving-end ceramic piezoelectric sheets transmitted through the data acquisition card;

[0016] The data processing module sequentially performs signal preprocessing and signal feature processing on the collected signals, and extracts the maximum amplitude voltage feature value of the F-wave packet;

[0017] The detection module is used to display the signal waveform, feature values, and damage determination results.

[0018] Combined with the first aspect, in the first possible implementation manner of the first aspect, the data processing module of the software system preprocesses and performs signal feature processing on the signals collected in the experiment to obtain stable and easy-to-analyze detection signals. The signal preprocessing includes signal amplification, wavelet denoising, and band-pass filtering. In the signal feature processing, the maximum amplitude of the detection signal is extracted, and the maximum amplitude ratio is defined.

[0019] Combined with the first aspect, in the second possible implementation manner of the first aspect, the signal preprocessing and signal feature processing of the data processing module of the software system; signal amplification is to amplify the signal through LabVIEW software; wavelet denoising reduces the influence of noise by decomposing the signal into wavelet components of different frequencies; band-pass filtering selects a Butterworth band-pass filter and selects appropriate high and low cut-off frequencies to further filter out unnecessary low-frequency and high-frequency noises; in the signal feature processing, the maximum amplitudes of the excitation signal and the received signal are extracted, and the maximum amplitude ratio is the ratio of the maximum amplitude of the excitation signal to the maximum amplitude of the received signal.

[0020] In combination with the first aspect, in the third possible implementation manner of the first aspect, the detection module is used for damage determination, and the damage is determined by calculating the amplitude ratio of the excitation signal to the received signal:

[0021] When the ratio ≤ 2.5, it is determined that there is no damage to the concealed part of the semi-exposed wooden column;

[0022] When the ratio > 2.5, it is determined that there is damage, and the greater the ratio, the higher the degree of damage.

[0023] In a second aspect, an ultrasonic guided wave detection method for damage to semi-exposed wooden columns in ancient buildings provided by an embodiment of the present invention includes: pasting the three ceramic piezoelectric wafers on the same side of the wooden column, with the excitation-end ceramic piezoelectric wafer located in the middle of the wooden column, and the receiving-end ceramic piezoelectric wafers close to the top and bottom of the wooden column and at the same distance from the excitation-section ceramic piezoelectric wafer, and measuring the size data of the wooden column and the position data of the ceramic piezoelectric wafers;

[0024] Connect the hardware components according to the signal transmission path and start the software system;

[0025] Input the size data of the measured semi-exposed wooden column and the position data of the three ceramic piezoelectric wafers into the software system, input a suitable excitation ultrasonic frequency value, and adjust the power amplifier multiple;

[0026] Collect the received signal and perform preprocessing and feature processing, and extract the maximum amplitude of the received signal;

[0027] The software system automatically calculates the ratio of the maximum amplitude of the excitation signal to the maximum amplitude of the received signal, and outputs the damage determination result and the degree of damage. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0029] Figure 1 It is a schematic diagram of the hardware architecture of an ultrasonic guided wave detection system for damage to semi-exposed wooden columns in ancient buildings provided by the present invention;

[0030] Figure 2 It is a schematic diagram of the software module of an ultrasonic guided wave detection system for damage to semi-exposed wooden columns in ancient buildings provided by the present invention;

[0031] Figure 3 It is a schematic diagram of the flow of an ultrasonic guided wave detection method for damage to semi-exposed wooden columns in ancient buildings provided by the present invention

[0032] In the figure, 1 is a computer; 2 is a data acquisition card; 3 is a power amplifier; 4 is an excitation-end ceramic piezoelectric wafer; 5 and 5' are receiving-end ceramic piezoelectric wafers; 6 is a signal conditioning module; 7 is a DC power supply; 8 is a half-exposed wooden column; 11 is an excitation module; 12 is a collection module; 13 is a data processing module; 14 is a detection module. Specific embodiments

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] The following Figure 1 、 Figure 2 and Figure 3 describe an ultrasonic guided wave detection system and method for damage to a half-exposed wooden column of an ancient building according to the present invention.

[0035] As Figure 1 shown, a schematic diagram of the hardware architecture of an ultrasonic guided wave detection system for damage to a half-exposed wooden column of an ancient building according to an embodiment of the present invention includes: a computer 1, a data acquisition card 2, a power amplifier 3, an excitation-end ceramic piezoelectric wafer 4, receiving-end ceramic piezoelectric wafers 5 and 5', a signal conditioning module 6, a DC power supply 7, and a half-exposed wooden column 8.

[0036] The computer 1 communicates with the data acquisition card 2 and is used for controlling the generation of ultrasonic guided wave signals, signal acquisition, and subsequent data processing;

[0037] The data acquisition card 2 is used for generating ultrasonic guided wave excitation signals at specific frequencies, acquiring ultrasonic guided wave signals after propagation through the half-exposed wooden column 8, and transmitting them to the computer;

[0038] The output end of the power amplifier 3 is connected to the excitation-end ceramic piezoelectric wafer 4 to amplify the excitation signal, and the input end is connected to the data acquisition card 2 to receive the original excitation signal;

[0039] The excitation-end ceramic piezoelectric wafer 4 is pasted in the middle of the outer side of the half-exposed wooden column 8, and the amplified excitation signal is converted into ultrasonic guided waves by the power amplifier 3 and input into the half-exposed wooden column 8;

[0040] The receiving-end ceramic piezoelectric wafers 5 and 5' are pasted at the top and bottom of the outer side of the half-exposed wooden column 8 and are used for receiving ultrasonic guided wave signals propagating in the half-exposed wooden column 8 to cover damage detection of different propagation paths;

[0041] The input end of the signal conditioning module 6 is connected to the receiving ceramic piezoelectric wafers 5 and 5', and performs high-pass filtering on the received signal to eliminate the interference of low-frequency noise.

[0042] The DC power supply 7 supplies power to the signal conditioning module 6 to ensure the stable operation of the system.

[0043] As Figure 2 shown, the software module schematic diagram of an ultrasonic guided wave detection system for damage to semi-exposed wooden columns in ancient buildings according to an embodiment of the present invention includes: an excitation module 11, a collection module 12, a data processing module 13, and a detection module 14.

[0044] The excitation module 11 generates an ultrasonic guided wave excitation signal with a specific frequency by controlling the data acquisition card 2.

[0045] The collection module 12 real-time collects the ultrasonic guided wave signals of the receiving ceramic piezoelectric wafers 5 and 5', and transmits the signals to the computer through the data acquisition card 2 to ensure data synchronization and low latency.

[0046] While the signal is being collected, the data processing module 13 performs corresponding signal preprocessing and signal feature processing.

[0047] The detection module 14 is used to display the signal waveform, eigenvalue, and damage determination result.

[0048] Corresponding to the hardware architecture schematic diagram of an ultrasonic guided wave detection system for damage to semi-exposed wooden columns in ancient buildings and the software module schematic diagram of an ultrasonic guided wave detection system for damage to semi-exposed wooden columns in ancient buildings provided in the above embodiment, the present invention also provides a flow schematic diagram of a method for detecting damage to semi-exposed wooden columns in ancient buildings using ultrasonic guided waves. Figure 3 It is a flow schematic diagram of a method for detecting damage to semi-exposed wooden columns in ancient buildings using ultrasonic guided waves provided by the present invention. As Figure 3 shown, the method includes:

[0049] S101, paste three ceramic piezoelectric wafers on the same side of the semi-exposed wooden column, and record the size data of the semi-exposed wooden column and the position data of the piezoelectric wafers.

[0050] The three ceramic piezoelectric wafers are respectively an excitation-end ceramic piezoelectric wafer and two receiving-end ceramic piezoelectric wafers. The excitation-end ceramic piezoelectric wafer is pasted in the middle of the outer side of the semi-exposed wooden column, and the receiving-end ceramic piezoelectric wafers are pasted at the top and bottom of the outer side of the semi-exposed wooden column, and are equidistant from the excitation-end ceramic piezoelectric wafer.

[0051] S102, connect the hardware components according to the signal transmission path, and start the software system.

[0052] S103. Input the dimension data of the measured semi-exposed wooden column and the position data of the piezoelectric chips into the software system, input an appropriate excitation ultrasonic frequency value, and adjust the power amplifier multiple.

[0053] S104. Collect the received signals, perform preprocessing and feature processing, and extract the maximum amplitude of the received signals.

[0054] Observe the received signals and extract the required characteristic values. If appropriate characteristic values are not obtained, change the power amplifier amplification multiple until the characteristic values are appropriate.

[0055] S105. The software system calculates the ratio of the maximum amplitude of the excitation signal to the maximum amplitude of the received signal, and outputs the damage determination result and the damage degree.

[0056] When the ratio ≤ 2.5, it is determined that there is no damage to the concealed part of the semi-exposed wooden column; when the ratio > 2.5, it is determined that there is damage, and the greater the ratio, the higher the damage degree.

[0057] An ultrasonic guided wave detection system and method for damage of semi-exposed wooden columns in ancient buildings according to an embodiment of the present invention can achieve accurate detection of damage to semi-exposed wooden columns in ancient buildings and accurate calculation of the damage degree; it can accurately judge the damage condition of semi-exposed wooden columns in ancient buildings and effectively serve the protection work of ancient buildings.

[0058] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative labor.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ultrasonic guided wave detection system for damage of semi-exposed wooden columns in ancient buildings, characterized in that It includes a hardware system and a software system; the hardware system includes a computer, a data acquisition card, a power amplifier, an excitation-end ceramic piezoelectric sheet, a receiving-end ceramic piezoelectric sheet, a signal conditioning module, and a DC power supply; The computer is connected to the data acquisition card and is used to control the generation, acquisition, and data processing of signals; The data acquisition card is used to generate ultrasonic guided wave excitation signals and acquire ultrasonic guided wave signals after propagation through the half-exposed wooden column; The power amplifier is connected to the data acquisition card and is used to amplify the excitation signal; The excitation-end ceramic piezoelectric sheet is pasted in the middle of the outer side of the half-exposed wooden column and is used to input the amplified ultrasonic guided wave signal into the half-exposed wooden column; The receiving-end ceramic piezoelectric sheet is pasted at the top and bottom of the outer side of the half-exposed wooden column and is used to receive the ultrasonic guided wave signals propagating in the half-exposed wooden column; The signal conditioning module is connected to the receiving-end ceramic piezoelectric sheet and is used to perform high-pass filtering on the received guided wave signals; The DC power supply powers the signal conditioning module; The software system includes an excitation module, an acquisition module, a data processing module, and a detection template: The excitation module controls the data acquisition card to generate excitation signals of specific frequencies; The acquisition module real-time acquires the ultrasonic guided wave signals of the receiving-end ceramic piezoelectric sheet transmitted through the data acquisition card; The data processing module sequentially performs signal preprocessing and signal feature processing on the acquired signals, and extracts the maximum amplitude voltage feature value of the F-wave packet; The detection module is used to display the signal waveform, feature values, and damage determination results.

2. The ultrasonic guided wave detection system for damage of semi-exposed wooden columns in ancient buildings according to claim 1, wherein The data processing module of the software system, in order to obtain stable and easy-to-analyze detection signals, performs signal preprocessing and signal feature processing on the signals collected in the experiment. The signal preprocessing includes signal amplification, wavelet noise reduction, and band-pass filtering. In the signal feature processing, the maximum amplitude of the detection signal is extracted, and the maximum amplitude change ratio is defined.

3. An ultrasonic guided wave detection system for damage of semi-exposed wooden columns of ancient buildings according to claim 2, characterized in that, The signal preprocessing and signal feature processing of the data processing module of the software system; The signal amplification is to amplify the signal through LabVIEW software; The wavelet noise reduction reduces the influence of noise by decomposing the signal into wavelet components of different frequencies; The band-pass filtering selects a Butterworth band-pass filter and selects appropriate high and low cut-off frequencies to further filter out unnecessary low-frequency and high-frequency noises; In the signal feature processing, the maximum amplitude of the detection signal is extracted. The maximum amplitude change ratio is the ratio of the maximum amplitude of the excitation signal to the maximum amplitude of the received signal.

4. The ultrasonic guided wave detection system for damage of semi-exposed wooden columns of ancient buildings according to claim 1, wherein The detection module is used for damage determination, and damage determination is performed by calculating the ratio of the maximum amplitude of the excitation signal to the maximum amplitude of the received signal: When the ratio ≤ 2.5, it is determined that there is no damage in the concealed part of the half-exposed wooden column; When the ratio > 2.5, it is determined that there is damage, and the greater the ratio, the higher the degree of damage.

5. An ultrasonic guided wave detection method for damage of semi-exposed wooden columns in ancient buildings based on the system described in claims 1-4, characterized in that, It includes the following steps: Pasting piezoelectric sheets: Paste three ceramic piezoelectric sheets on the same side of the wooden column. The excitation-end ceramic piezoelectric sheet is located in the middle of the wooden column, and the two receiving-end ceramic piezoelectric sheets are respectively located at the top and bottom of the wooden column and are at the same distance from the excitation-section ceramic piezoelectric sheet. Record the size data of the wooden column and the position data of the ceramic piezoelectric sheets; System connection: Connect the hardware components according to the signal transmission path and start the software system; Parameter input: Input the dimension data of the measured semi-exposed wooden column and the position data of the ceramic piezoelectric wafer in the software system, input an appropriate excitation ultrasonic frequency value, and adjust the power amplifier multiple; Signal acquisition and processing: Acquire the received signal and perform preprocessing and feature processing, and extract the maximum amplitude of the received signal; Damage determination: Automatically calculate the ratio of the maximum amplitude of the excitation signal to the maximum amplitude of the received signal according to the software, and output the damage determination result and the degree of damage.

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