A concrete damage detection method and system based on acoustic emission technology

Abstract

The present invention relates to the field of concrete detection technology, and in particular to a concrete damage detection method and system based on acoustic emission technology, which is used to solve the problems of low detection accuracy and long detection time in fiber concrete damage detection in the prior art, and comprises the following steps: preparing fiber concrete, the fiber concrete comprising fiber and concrete; analyzing the influence of the fiber under different distribution conditions on the performance of the fiber concrete and the mechanical properties of the fiber concrete; using an acoustic emission signal acquisition system to collect the sound wave signal inside the fiber concrete; analyzing the integrity and continuity of the sound wave signal in the frequency domain; if the sound wave signal is a complete sound wave signal, judging the mutation position and transmission time of the sound wave signal, and determining the damage value of the fiber concrete damage point. The method is not only simple and efficient but also has strong applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete detection, and in particular to a concrete damage detection method and system based on acoustic emission technology. Background Art

[0002] With the continuous acceleration of social economy and urbanization, the number of buildings in cities is increasing, and concrete materials are indispensable. Concrete materials have advantages such as good tensile strength and long-lasting durability. However, ordinary concrete has problems such as cracking, failure and gradual deterioration of durability over time. Fiber concrete formed by adding a certain amount of chopped fiber material to cement as needed can solve the problems of ordinary concrete in construction. However, fiber concrete materials are also prone to certain problems and damage. For example, unreasonable distribution of fiber chopped materials in concrete will cause performance problems of fiber concrete in later use.

[0003] Therefore, researchers in the field of construction have conducted some research on issues such as fiber concrete damage, and have achieved certain results in detecting fiber concrete damage, but there are also some detection drawbacks. The existing fiber concrete damage detection method has low detection accuracy and takes a long time to detect, so it is necessary to further explore more accurate and efficient detection methods; in addition, the existing fiber concrete damage detection process is relatively complicated and difficult to operate. Summary of the invention

[0004] In view of the defects in the prior art, the present invention provides a method and system for concrete damage detection based on acoustic emission technology.

[0005] The embodiment of the present invention is implemented as follows. In the first aspect, the present invention provides a method for concrete damage detection based on acoustic emission technology to solve the above problems, which includes the following steps: preparing fiber concrete, the fiber concrete includes fiber and concrete; analyzing the influence of the fiber under different distribution conditions on the performance of the fiber concrete and the mechanical properties of the fiber concrete; using an acoustic emission signal acquisition system to collect the sound wave signal inside the fiber concrete; analyzing the integrity and continuity of the sound wave signal in the frequency domain; if the sound wave signal is a complete sound wave signal, judging the mutation position and transmission time of the sound wave signal, and determining the damage value of the fiber concrete damage point. This method is not only simple and efficient but also has strong applicability.

[0006] Optionally, the method further includes repairing the sound wave signal if the sound wave signal is an incomplete sound wave signal.

[0007] Optionally, the method further includes analyzing the distribution of fibers in the fiber concrete, wherein the distribution includes fiber longitudinal distribution and fiber random distribution.

[0008] Optionally, the fiber forward distribution satisfies:

[0009]

[0010]

[0011]

[0012] in, Represents the stress value of the fiber concrete, represents the force value of the fiber, Represents the stress value of the concrete; represents the balance state of tension and bonding force of the fiber, represents the fiber diameter length, represents the effective bonding coefficient, represents the bonding stress value between the fiber and the fiber concrete; represents the total stress of the fiber concrete, Represents the total volume change rate of the fiber.

[0013] Optionally, the fibers are randomly distributed in the following order:

[0014]

[0015]

[0016]

[0017]

[0018]

[0019] in, represents the distribution state of the fiber in concrete, represents the angle between the fiber axis and the force direction of the fiber, represents the axial angle in the fiber axis, Represents the fiber diameter length; represents the reinforcing efficiency value of the random fiber specimen; P represents the tensile strength of the fiber concrete, represents the average load value of the fiber concrete tensile strength, Represents the load value borne by the fiber concrete when damage occurs; represents the shear strength of the fiber concrete, represents the content of the fiber in the fiber concrete, represents a characteristic ratio of the fiber to the concrete; represents the compressive strength of the fiber concrete, represents the maximum load value of the fiber concrete, Represents the total area of ​​the fiber concrete; in actual situations, the distribution of fibers in general fiber concrete is randomly distributed.

[0020] Optionally, the receiving the sound wave signal inside the fiber concrete includes:

[0021] Using an acoustic transmitter to transmit a signal into the fiber concrete;

[0022] Collect the acoustic wave signal using a sensor;

[0023] Amplifying the sound wave signal using an amplifier;

[0024] The sound wave signal inside the fiber concrete is collected by a signal collector.

[0025] Optionally, the sound wave signal is converted into the frequency domain, and if the sound wave signal is an incomplete sound wave signal, the sound wave signal is repaired, including using a continuous wavelet transform to repair the incomplete sound wave signal, and the sound wave signal and the continuous wavelet transform satisfy the following relationship:

[0026]

[0027]

[0028] in, represents the Fourier transform result of the acoustic wave signal, and is a real number, Represents the frequency of conversion; Representative continuous wavelet transform, n and is a natural number, represents the oscillation coefficient, represents the angular frequency of the acoustic wave signal, Represents the stretching frequency of the sound wave signal.

[0029] Optionally, the sound wave signal includes a continuous sound wave signal and a discontinuous sound wave signal, which respectively satisfy the following relationships:

[0030]

[0031]

[0032] in, represents the continuous sound wave signal, represents the stretch factor, represents the translation factor; represents the discontinuous sound wave signal, Represents the continuous transformation ratio value, Represents the result of continuous transformation of the discontinuous sound wave signal.

[0033] Optionally, the transmission time and the damage value respectively satisfy the following relationship:

[0034]

[0035]

[0036] in, represents the transmission time, , Represent the time difference of different sensors. represents the acoustic coefficient, Represents the running speed of the sound wave signal; represents the damage value of the i-th damage point, and represents the three-dimensional coordinate value of the sensor, and represents the three-dimensional coordinate value of the damage point obtained by the three-dimensional positioning method, Represents the signal feedback duration, Represents the propagation speed of the acoustic wave signal in the fiber concrete.

[0037] In summary, the present invention completes the mechanical property analysis by analyzing the influence of fibers on the performance of fiber concrete under different states, and on this basis, invents a method for concrete damage detection based on acoustic emission technology. The method has a wide range of applications, is not only simple and easy to implement, but also solves the problems of low detection accuracy and long detection time in the existing fiber concrete damage detection technology. In the second aspect, the present invention provides a system for concrete damage detection based on acoustic emission technology, which is used for concrete damage detection, including the following steps: using the signal generating device to emit sound waves into the fiber concrete to generate sound wave signals in the fiber concrete; using the data processing device to analyze the mechanical properties of the fiber concrete; receiving, amplifying and collecting the sound wave signals; analyzing the integrity and continuity of the sound wave signals in the frequency domain, and repairing incomplete sound wave signals; judging the mutation position and transmission time of the complete sound wave signals, and determining the damage value of the damage point of the fiber concrete; the data processing device is connected to the signal generating device. The device has a simple structure and good detection effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 This is a flow chart of fiber concrete damage detection according to an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of a fiber concrete preparation process according to an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the damage signal collection process according to an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of damage point detection accuracy analysis results according to an embodiment of the present invention;

[0043] Figure 5 Schematic diagram of time consumption analysis of damage point detection using three methods according to an embodiment of the present invention; Figure 6 The figure is a schematic diagram of the components and operation sequence of the fiber concrete damage detection system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not need to be adopted to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, software or methods are not specifically described.

[0045] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or subcombination. In addition, it should be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale.

[0046] It should be noted in advance that, in an optional embodiment, except for independent explanations, the same symbols or letters appearing in all formulas have the same meanings.

[0047] See also Figure 1 In an optional embodiment, the present invention provides a method for concrete damage detection based on acoustic emission technology, comprising the following steps:

[0048] S1. Prepare fiber concrete.

[0049] The fiber concrete is in the shape of a cuboid. In this embodiment, 10 fiber concretes are made for experimental analysis. The length, width and height of the fiber concretes are kept consistent, and the fiber concretes are numbered from 1 to 10. Two damage points are set in each fiber concrete, but the position of each damage point is different. For further information, please refer to Figure 2 , S1 specifically includes the following steps:

[0050] S11. Mixing cement and fiber.

[0051] Specifically, in this embodiment, a certain amount of aggregate needs to be added to the cement, and the aggregate includes coarse aggregate and fine aggregate; the fiber includes polypropylene fiber and steel fiber; further, the cement, the fiber, the coarse aggregate and the fine aggregate are added together and then dry-mixed for one minute to make the cement, the fiber, the coarse aggregate and the fine aggregate more evenly mixed, and finally form a mixture 1.

[0052] More specifically, the cement is of P.O42.5 grade; the maximum diameter of the coarse aggregate is about 25 mm, and the particle size modulus of the fine aggregate is about 2.8; the length of the polypropylene fiber is 15 mm, the diameter of the polypropylene fiber is 30 μm, the elastic modulus of the polypropylene fiber is 4.0 GPa, and the tensile strength of the polypropylene fiber is 300 MPa; the length of the steel fiber is 38 mm, the diameter of the steel fiber is 600 μm, the elastic modulus of the steel fiber is 210 GPa, and the tensile strength of the steel fiber is 1050 MPa; the mixing ratio of the cement, the aggregate and the fiber can refer to the mixing ratio of cement, aggregate and fiber in the existing fiber concrete, and the specific mixing ratio is not limited here.

[0053] S12. Add 90% water.

[0054] Specifically, in this embodiment, the water is clean tap water, and the water for making the fiber concrete is not added all at once, but 90% of the prepared water is added first, and the remaining water is convenient for the subsequent steps; further, after adding the water, it needs to be stirred for 30 seconds to form a uniformly mixed mixture 2.

[0055] S13. Add water reducing agent and remaining water.

[0056] Specifically, in this embodiment, the water reducer is first added to the remaining water and mixed evenly to form a mixed solution, and then the mixed solution is added to the mixture 2 and stirred for 30 seconds to form a uniformly mixed fiber concrete slurry, so that the water reducer can maximize the plasticity of the fiber concrete and reduce the shrinkage rate of the fiber concrete.

[0057] More specifically, the water reducing agent is of FDN model, has a relatively low density, an acidity of 6, and a water reducing efficiency of about 20%.

[0058] S14. pouring fiber concrete.

[0059] Specifically, in this embodiment, the fiber concrete slurry completed in S14 is used to cast the fiber concrete.

[0060] It should be noted that in this embodiment, the method and steps for preparing the fiber concrete are only for illustrating this embodiment, and are not specific production limitations. In other optional embodiments, the specific production method is not limited based on the ability to produce suitable fiber concrete.

[0061] S2. Analyze the mechanical properties of the fiber concrete under different fiber distribution conditions.

[0062] Among them, the damage detection of the fiber concrete is greatly affected by the fiber distribution, and the distribution includes fiber forward distribution and fiber random distribution. These two different distribution states make the fiber concrete present different mechanical properties. Mechanical analysis of the fiber concrete with these two different fiber distribution states is helpful to determine the distribution of fibers in the fiber concrete, find a method for fiber concrete damage detection with a wider range of applications, and provide a data basis for subsequent damage detection. S2 specifically includes the following steps:

[0063] S21. Analyze the mechanical properties of the fiber concrete under the condition of longitudinal fiber distribution.

[0064] Assuming that the fiber length is a fixed value, the force value of the fiber concrete is analyzed. , fiber tension and bonding force equilibrium state , respectively satisfying the following relations:

[0065]

[0066] Regardless of the position of the fiber in the fiber concrete, the tension and bonding force on the fiber are in a balanced state, that is:

[0067]

[0068] in, Represents the magnitude of the force on the fiber, Represents the stress value of the concrete; represents the fiber diameter length, represents the effective bonding coefficient, Represents the bonding stress value between the fiber and the fiber concrete.

[0069] The stress and volume change rate of the fiber in the fiber concrete will change to a certain extent. These changes are mainly reflected in the interior of the fiber concrete. Therefore, it is necessary to determine the physical state of the fiber concrete when the fiber is distributed in the forward direction. The physical state of the fiber concrete at this time can be analyzed by the following relationship:

[0070]

[0071] in, represents the total stress of the fiber concrete, Represents the total volume change rate of the fiber.

[0072] S22. Analyze the mechanical properties of the fiber concrete under the condition of random fiber distribution.

[0073] The mechanical properties of the fiber concrete under the condition of random fiber distribution are analyzed, including the distribution state of the fiber in the concrete. , Fiber reinforcement efficiency , tensile strength P of fiber concrete, shear strength of fiber concrete and compressive strength of fiber reinforced concrete .

[0074] When the fibers are randomly distributed, the angle between the fiber axis and the force direction of the fibers will affect the performance of the fiber concrete. When the fibers are randomly distributed, the distribution state of the fibers in the concrete And the reinforcing efficiency of the fiber on the concrete Satisfies the following relationship:

[0075]

[0076]

[0077] Wherein, the angle between the fibers is 0, represents the angle between the fiber axis and its force direction, represents the axial angle in the fiber axis;

[0078] After analyzing the performance of the fiber in the fiber concrete, it is necessary to analyze the overall mechanical properties of the fiber concrete. When the tensile hardening bond coefficient of the fiber concrete is expressed by load, the tensile strength P is expressed as:

[0079]

[0080] in, represents the average load value of the fiber concrete tensile strength, Represents the load value borne by the fiber concrete when damage occurs;

[0081] The fibers can not only improve the tensile strength of the fiber concrete, but also improve the shear strength of the fiber concrete. When the fiber volume increases, the shear strength of the fiber concrete It can be expressed as:

[0082]

[0083] in, represents the content of the fiber in the fiber concrete, represents a characteristic ratio of the fiber to the concrete;

[0084] Based on the above analysis, the compressive strength of the fiber concrete is determined. It can be expressed as:

[0085]

[0086] in, represents the maximum load value of the fiber concrete, Represents the total area of ​​the fiber concrete.

[0087] It should be noted that, after calculation, the distribution of the fibers in the fiber concrete used in this embodiment is all random distribution of the fibers.

[0088] S3. Using an acoustic emission signal acquisition system to collect the sound wave signal inside the fiber concrete.

[0089] Among them, S3 specifically includes the following steps:

[0090] S31. Use an acoustic transmitter to transmit a signal into the fiber concrete.

[0091] Specifically, in this embodiment, the acoustic emitter has a resonant frequency of 200 kHz, is supported by 220V alternating current, and has 18 acoustic emission signal channels and 12 external parameter channels.

[0092] S32: Use a sensor to collect the sound wave signal.

[0093] Specifically, in this embodiment, the sensor is installed on the surface of the fiber concrete, the installation position of the sensor can be selected arbitrarily, the position of the damage point inside the fiber concrete remains unchanged, and different detection results can be obtained by changing the position of the sensor.

[0094] More specifically, the number of sensors used in this embodiment is 10. In other optional embodiments, the number of sensors and the positions of the sensors are not limited.

[0095] S33, using an amplifier to amplify the sound wave signal.

[0096] S34: Use a signal collector to collect the sound wave signal.

[0097] S4. Analyze the integrity and continuity of the sound wave signal in the frequency domain.

[0098] Among them, by converting the sound wave signal into the frequency domain for analysis by means of Fourier transform, the abnormal situation of the sound wave signal can be better reflected, and it is convenient to analyze the integrity and continuity of the sound wave signal. S4 specifically includes the following steps:

[0099] S41. Analyze the integrity of the sound wave signal in the frequency domain.

[0100] Among them, converting the sound wave signal into the frequency domain to analyze the waveform of the sound wave signal can better reflect the abnormal situation of the sound wave signal. S41 specifically includes the following two situations:

[0101] B1. The sound wave signal is a complete sound wave signal.

[0102] Specifically, in this embodiment, the sound wave signal is converted into the frequency domain. When the sound wave signal is a complete sound wave signal, the next step is directly executed, and the sound wave signal satisfies the following relationship:

[0103]

[0104] in, represents the Fourier transform result of the acoustic wave signal, and is a real number, Represents the frequency of conversion.

[0105] B2. The sound wave signal is an incomplete sound wave signal.

[0106] In another embodiment, due to the distribution state of the fibers inside the fiber concrete, the collected sound wave signals contain incomplete sound wave signals, which are easy to interfere with the sound wave signals, resulting in large errors in damage detection and positioning. Therefore, in order to ensure the integrity of the sound wave signals, the incomplete sound wave signals need to be repaired.

[0107] Specifically, in this embodiment, the sound wave signal is converted into the frequency domain. When the sound wave signal is an incomplete sound wave signal, the incomplete sound wave signal is repaired using a continuous wavelet transform. The sound wave signal and the continuous wavelet transform satisfy the following relationship:

[0108]

[0109]

[0110] in, represents the Fourier transform result of the acoustic wave signal, and is a real number, Represents the frequency of conversion; Representative The continuous wavelet transform, n and is a natural number, represents the oscillation coefficient, represents the angular frequency of the acoustic wave signal, Represents the signal stretching frequency.

[0111] S42. Analyze the continuity of the sound wave signal in the frequency domain.

[0112] The sound wave signal includes a continuous sound wave signal and a discontinuous sound wave signal.

[0113] Specifically, in this embodiment, after the continuous wavelet in the fiber concrete is stretched and translated, the continuous sound wave signal can be obtained, and the continuous sound wave signal satisfies the following relationship:

[0114]

[0115] in, represents the continuous sound wave signal obtained by scaling and translating the continuous wavelet in the fiber concrete, represents the stretch factor, Represents the translation factor.

[0116] The discontinuous sound wave signal will also interfere with the sound wave signal, resulting in a large error in damage detection and positioning. Therefore, for any discontinuous sound wave signal in the fiber concrete, it is necessary to perform a continuous transformation, and the discontinuous sound wave signal satisfies the following relationship:

[0117]

[0118] in, represents the discontinuous sound wave signal, Represents the continuous transformation ratio value, Represents the result of continuous transformation of the discontinuous sound wave signal.

[0119] S5. If the sound wave signal is a complete sound wave signal, determine the mutation position and transmission time of the sound wave signal, and determine the damage value of the fiber concrete damage point.

[0120] In another optional embodiment, when the damage point appears inside the fiber concrete, the path of the sound wave signal will be deformed to form the mutant signal. The position of the mutant signal is also the position of the damage point. Therefore, it is only necessary to determine the position of the mutant signal to determine the position of the damage point.

[0121] Furthermore, when the sound wave signal reaches the damage point, the sound wave signal collected by the sensor will have a certain time difference, and the transmission of the sound wave signal will not be interrupted and will keep moving forward at a certain speed, which is specifically manifested in that the waveform of the collected sound wave signal undergoes a sudden change. Therefore, the position of the mutant signal can be determined by the waveform mutation position of the sound wave signal. The first mutation position of the sound wave signal is the starting point of the mutant signal, that is, the starting point of the damage point. Damage detection can be achieved by determining this point.

[0122] Specifically, in this embodiment, the transmission time and the damage value respectively satisfy the following relationship:

[0123]

[0124]

[0125] in, represents the transmission time, , Represent the time difference of different sensors. represents the acoustic coefficient, Represents the running speed of the sound wave signal; represents the damage value of the i-th damage point, the damage value The size of is used to judge the damage degree of the damage point. represents the three-dimensional coordinate value of the sensor, and represents the three-dimensional coordinate value of the damage point obtained by the three-dimensional positioning method, represents the feedback duration of the sound wave signal, Represents the propagation speed of the acoustic wave signal in the fiber concrete.

[0126] It should be noted that, in some cases, the actions described in the specification can be performed in a different order and still achieve the desired results. In this embodiment, the specific step order and material type given are only for the purpose of making the embodiment clearer and easier to explain, rather than limiting it.

[0127] In order to make this embodiment clearer and to highlight the advantages of the present invention over the existing concrete damage detection technology, the results of this embodiment will be specifically and detailedly analyzed below.

[0128] See also Figure 4-Figure 5In this embodiment, the existing methods 1 and 2 for detecting concrete damage are used as comparative tests of this method to detect the damage points in the fiber concrete respectively. The method 1 is a method for determining the damage of the fiber concrete by means of a fiber concrete damage degradation detection model, and the method 2 is a method for detecting the damage of the fiber concrete by using laser thermal excitation infrared imaging technology.

[0129] Specifically, in this embodiment, see Figure 4 ,Depend on Figure 4 From the middle curve, we can see that the detection accuracy of method 1 and method 2 are lower than that of this method, which is higher than 90%. The detection accuracy of method 1 and method 2 fluctuates greatly, while the detection accuracy of this method is relatively stable. Therefore, it can be concluded that the detection result of this method is better and has a certain degree of credibility.

[0130] Specifically, in this embodiment, see Figure 5 ,Depend on Figure 5 It can be seen from the changes in the three curves that the detection time of this method is shorter, and is always shorter than the detection time of method 1 and the detection time of method 2; the detection time of method 1 and the detection time of method 2 are longer, which seriously affects the detection effect. In comparison, the detection time of this method is shorter and more feasible.

[0131] See also Figure 6 An embodiment of the present invention also provides a system for concrete damage detection based on acoustic emission technology, which is used to perform fiber concrete damage detection using a method for concrete damage detection based on acoustic emission technology of the present invention, including a signal generating device and a data processing device, which has not only a simple structure but also a fast detection speed and high detection accuracy.

[0132] The signal generating device A1 uses acoustic emission technology to transmit a signal to the fiber concrete, so that a sound wave signal is generated inside the fiber concrete. The sound wave signal propagates in the fiber concrete. When the sound wave signal encounters a damage point, the path of the sound wave signal will undergo a certain deformation.

[0133] A data processing device A2 is connected to the signal generating device A1. The data processing device A2 can contact the fiber concrete, automatically analyze the mechanical properties of the fiber concrete and obtain the fiber distribution in the fiber concrete. At the same time, after the signal generating device A1 transmits a signal to the fiber concrete, the data processing device A2 can receive the sound wave signal, amplify the sound wave signal, and collect the amplified sound wave signal. The collected sound wave signal is converted to the frequency domain to analyze its completeness and continuity. If the sound wave signal is incomplete, it needs to be repaired with the help of continuous wavelet transform, and the discontinuous sound wave signal is continuously transformed. After obtaining the complete sound wave signal, the position and transmission time of the mutant signal are determined according to the waveform of the sound wave signal. The position of the mutant signal is the position of the damage point. Finally, the damage value of the damage point of the fiber concrete is calculated according to the position of the mutant signal and the transmission time.

[0134] In summary, the present invention analyzes the influence of fiber on the performance of fiber concrete under different states, determines the efficiency of fiber reinforcement on fiber concrete, completes the mechanical performance analysis, and designs a method for concrete damage detection based on acoustic emission technology and a system for concrete damage inspection using the method on this basis. The method and system collect the internal sound wave signal of fiber concrete with the help of acoustic emission technology, determine the integrity of the sound wave signal through frequency domain analysis, and introduce continuous wavelet transform to repair the incomplete sound wave signal, determine the position of the mutant signal and the transmission time, and finally determine the damaged point through the three-dimensional positioning method, and calculate the damage value of the damaged point. Since in actual situations, the distribution of fibers in general fiber concrete is randomly distributed, the fiber concrete damage detection method provided by the present invention has a wider scope of application, not only the detection process is simple and easy to operate, but also solves the problems of low detection accuracy and long detection time in the existing fiber concrete damage detection technology. The test results also show that the detection accuracy of the present method is higher than 90%, indicating that the present invention has high reliability and feasibility.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for concrete damage detection based on acoustic emission technology, characterized in that: The steps include: preparing fiber concrete, the fiber concrete comprising fibers and concrete; Analyzing the distribution of fibers in the fiber concrete, wherein the distribution includes fiber forward distribution and fiber random distribution; The fiber forward distribution satisfies: in, Represents the stress value of the fiber concrete, represents the force value of the fiber, Represents the stress value of the concrete; represents the balance state of tension and bonding force of the fiber, represents the fiber diameter length, represents the effective bonding coefficient, represents the bonding stress value between the fiber and the fiber concrete; represents the total stress of the fiber concrete, represents the total volume change rate of the fiber; The fiber random distribution satisfies: in, represents the distribution state of the fiber in concrete, represents the angle between the fiber axis and the force direction of the fiber, represents the axial angle in the fiber axis, Represents the fiber diameter length; represents the reinforcing efficiency value of the specimen with random fibers; P represents the tensile strength of fiber concrete, represents the average load value of the fiber concrete tensile strength, Represents the load value borne by the fiber concrete when damage occurs; represents the shear strength of the fiber concrete, represents the content of the fiber in the fiber concrete, represents a characteristic ratio of the fiber to the concrete; represents the compressive strength of the fiber concrete, represents the maximum load value of the fiber concrete, represents the total area of ​​the fiber concrete; Analyzing the mechanical properties of the fiber concrete under different distribution conditions of the fibers; Receiving a sound wave signal inside the fiber concrete; The sound wave signal includes a continuous sound wave signal and a discontinuous sound wave signal, which respectively satisfy the following relationship: in, represents the continuous sound wave signal, represents the stretch factor, represents the translation factor; represents the discontinuous sound wave signal, Represents the continuous transformation ratio value, represents the result of continuous transformation of the discontinuous sound wave signal; Analyzing the integrity and continuity of the acoustic wave signal in the frequency domain; If the sound wave signal is a complete sound wave signal, determine the mutation position and transmission time of the sound wave signal, and determine the damage value of the fiber concrete damage point; The transmission time and the damage value respectively satisfy the following relationship: in, represents the transmission time, , Represent the time difference of different sensors. represents the acoustic coefficient, Represents the running speed of the sound wave signal; represents the damage value of the i-th damage point, represents the three-dimensional coordinate value of the sensor, and represents the three-dimensional coordinate value of the damage point obtained by the three-dimensional positioning method, Represents the signal feedback duration, Represents the propagation speed of the acoustic wave signal in the fiber concrete; The sound wave signal is converted into the frequency domain. If the sound wave signal is an incomplete sound wave signal, the sound wave signal is repaired, including using a continuous wavelet transform to repair the incomplete sound wave signal. The sound wave signal and the continuous wavelet transform satisfy the following relationship: in, represents the Fourier transform result of the acoustic wave signal, and is a real number, Represents the frequency of conversion; Representative continuous wavelet transform, n and is a natural number, represents the oscillation coefficient, represents the angular frequency of the acoustic wave signal, Represents the stretching frequency of the sound wave signal.

2. The method for detecting concrete damage based on acoustic emission technology according to claim 1, characterized in that: The receiving of the sound wave signal inside the fiber concrete comprises: Using an acoustic transmitter to transmit a signal into the fiber concrete; Collect the acoustic wave signal using a sensor; Amplifying the sound wave signal using an amplifier; The acoustic wave signal is collected by a signal collector.

3. A system for concrete damage detection based on acoustic emission technology, the system using a method for concrete damage detection based on acoustic emission technology according to any one of claims 1-2, characterized in that: include: A signal generating device, the signal generating device is used to emit sound waves into the fiber concrete so as to generate sound wave signals in the fiber concrete; A data processing device, the data processing device is used to automatically analyze the mechanical properties of the fiber concrete and obtain the fiber distribution in the fiber concrete; Receive the sound wave signal, amplify the sound wave signal, and collect the amplified sound wave signal; convert the collected sound wave signal to the frequency domain to analyze its completeness and continuity. If the sound wave signal is incomplete, repair it with the help of continuous wavelet transform, and continuously transform the discontinuous sound wave signal; after obtaining the complete sound wave signal, determine the position and transmission time of the mutant signal according to the waveform of the sound wave signal, the position of the mutant signal is the position of the damage point, and finally calculate the damage value of the damage point according to the position of the mutant signal and the transmission time; the data processing device is connected to the signal generating device.

Images