A method for locating damage of concrete components based on correction of apparent wave velocity of acoustic emission

Abstract

The present invention discloses a method for locating damage of concrete components based on correction of acoustic emission apparent wave velocity, including step 1: conducting an axial compression test of a concrete cubic test block, collecting acoustic emission signals of the entire loading process and damaged lead-breaking signals of damage mark points; step 2: using damaged lead-breaking signals, calculating the acoustic emission apparent wave velocity and relative apparent wave velocity under three design conditions and two spatial qualitative relationships; step 3: establishing two-dimensional scattered points with damage mark points and relative apparent wave velocity as coordinates, and generating an empirical formula for two-dimensional scattered points through cubic polynomial fitting; step 4: interpolating and expanding the empirical formula, substituting the expanded empirical formula into any time-difference positioning algorithm based on a constant wave velocity as a premise to complete the algorithm update. The present invention can solve the problem of drift of damage positioning accuracy with damage degree under the assumption of constant wave velocity, and realize accurate damage positioning of damaged components.

Description

Technical Field

[0001] The invention belongs to the field of engineering structure nondestructive testing technology and structural health monitoring technology, and specifically, is a concrete component damage location method based on acoustic emission apparent wave velocity correction. Background Art

[0002] Concrete materials are the main building materials for today's engineering structures. The damage and cracking of concrete structures are the focus of attention in the fields of non-destructive testing technology and health monitoring technology. With the gradual improvement of safety awareness in the engineering community, a comprehensive technological shift from post-detection to real-time monitoring is bound to come, which provides a broad application scenario for acoustic emission testing technology (AE). Damage location, damage qualitative and damage quantification are the three key indicators for judging the pros and cons of non-destructive testing technology, and damage location is the basic step, and AE technology is no exception.

[0003] Since the advent of AE technology, the industry has never stopped exploring the optimization of AE damage location algorithms. After decades of development, the time difference location algorithm TOA has become the location algorithm branch with the most categories, the widest application, and the most research in the AE damage location algorithm system. With the breakthrough of nanosecond sampling technology and various algorithm optimization updates around threshold recognition, phase analysis, and coherence analysis, the digital time difference recognition technology in TOA has been nearly perfected. If the high precision of digital time difference recognition technology is recognized, under the basic assumption of TOA that the wave speed is constant and propagates in a straight line, the product of the wave speed and the time difference will directly reflect the relative spatial position relationship between the damage point and the sensor array, thereby achieving high-precision damage location. Of course, this also depends on the logical conflict processing of the redundant sensor array and the deep feature extraction of the sparse sensor. This invention does not discuss this branch research trend. A large number of studies have shown that when the component to be detected is in an elastic state, even if the AE wave velocity research is deepened to the elastic modulus, Poisson's ratio, material density, anisotropy, and even the material mesoscopic or microscopic level, the above assumptions are still approximately valid. However, when the component to be detected exceeds a certain stress limit, the assumption that AE propagates in a straight line will be overturned first, and due to the influence of the randomness of the cracks, the actual propagation path will not be detected. At this time, most time-difference positioning algorithms will produce principle errors, the positioning accuracy will drop sharply, and the positioning error will drift as the damage of the component increases. Summary of the invention

[0004] The purpose of the present invention is to provide a concrete component damage location method based on acoustic emission apparent wave velocity correction, so as to overcome the shortcomings of existing time-difference location algorithms in locating damaged concrete components with poor accuracy.

[0005] In order to solve the above technical problems, the specific technical solutions adopted by the present invention are as follows.

[0006] A method for locating damage of concrete components based on acoustic emission apparent wave velocity correction, characterized by comprising the following steps:

[0007] Step 1: Conduct an axial compression test on a concrete cube specimen, collect acoustic emission signals throughout the loading process, use a set of designed constants of the equivalent stress ratio as damage markers, and divide the specimen into five typical damaged stages; during the loading process, when the equivalent stress ratio of the specimen reaches the damage marker, suspend loading and conduct an acoustic emission lead-breaking test to complete the collection of damaged lead-breaking signals; after the lead-breaking test, continue loading until the next damage marker and repeat the above steps, and terminate the test after the test termination conditions are met;

[0008] Step 2: Using the collected damaged lead-break signals, calculate the acoustic emission apparent wave velocity and relative apparent wave velocity under two spatial qualitative relationships of three design conditions respectively;

[0009] The maximum particle sizes of coarse aggregates of the test blocks under the three design conditions are different, namely 16 mm, 20 mm, and 26.5 mm;

[0010] The two spatial qualitative relationships refer to the qualitative description of the relative spatial position relationship between any two sensor combinations in the sensor array, specifically, the two sensors are located on the same surface and on different surfaces of the cubic test block, which are used to calculate the surface wave velocity and the body wave velocity respectively;

[0011] The apparent wave velocity is calculated as follows

[0012]

[0013] The superscript g is the number of the damage mark point, and the subscript k is the number of the spatial qualitative relationship between sensors i and j; k = 1 indicates the same-plane situation, and k = 2 indicates the different-plane situation; i is the number of the sensor next to the lead break point. Since the lead break point traverses the sensor array, i is 1, 2...n, where n is the total number of sensors in the array; j is the number of the sensor that meets the kth type of spatial qualitative relationship with sensor i, k z is the number of combinations of sensor i and sensor j that meet the kth spatial qualitative relationship, n c is the number of repeated lead breaks at the same lead break position, S(i,j) is the actual spatial distance between sensor i and sensor j, is the time difference of the acoustic emission signal of the sensor combination measured by the cth repeated lead breaking under the zth sensor combination that meets the kth spatial qualitative relationship in the lead breaking test with the damage identification point numbered g, It is the apparent wave velocity obtained for all the broken leads that meet the k-th spatial qualitative relationship in the broken lead test with the damage identification point numbered g;

[0014] The relative apparent wave velocity is calculated as follows:

[0015]

[0016] is the relative apparent wave velocity obtained for all the lead breaks that meet the kth type of spatial qualitative relationship in the lead break test with the damage identification point numbered g, is the apparent wave velocity of the initial damage marker point under the kth type of spatial qualitative relationship;

[0017] Step 3: Establish two-dimensional scattered points with damage markers and relative apparent wave velocity as coordinates, and generate an empirical formula for the two-dimensional scattered points through cubic polynomial fitting;

[0018] Step 4: Interpolate and expand the empirical formula, and substitute the expanded empirical formula into any time-difference positioning algorithm based on a constant wave velocity to calculate the update of the apparent wave velocity as the damage evolves, thereby greatly reducing the damage location deviation of the time-difference positioning algorithm for damaged concrete components.

[0019] The test termination condition is to complete the one-time ultimate compressive strength f cl After loading, unload and load again to 0.5f cl ;

[0020] The equivalent stress ratio is calculated according to the following formula

[0021]

[0022] is the equivalent stress ratio, σ c is the compressive stress value of the test block during loading, f cl is the ultimate compressive strength of the test block.

[0023] The relationship between the damage mark points, the design values ​​of the equivalent stress ratios corresponding to the damage mark points and the damage stage division of the test block is as follows:

[0024] Initial damage landmark point, take The test block is not loaded and is considered as a non-destructive component;

[0025] The first injury landmark point is The test block is in the elastic compaction stage;

[0026] The second injury landmark point is The specimen is in the elastoplastic-plastic damage stage;

[0027] The third injury landmark point is The specimen is in the elastoplastic-plastic damage stage;

[0028] The fourth injury landmark point is The specimen is in the plastic damage stage;

[0029] The fifth injury landmark point is The specimen is in the secondary damage stage.

[0030] The step three includes the following points:

[0031] The cubic polynomial fitting adopts the least squares method, and the fitting formula is as follows

[0032]

[0033] It represents the relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of q mm under the kth type of spatial qualitative relationship. A, B, and C are fitting coefficients. The constant 1 is set to ensure that

[0034] For the test block with the maximum particle size of coarse aggregate equal to 16 mm, the empirical formula is as follows:

[0035]

[0036] f1 16 (·) represents the surface wave relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of 16 mm. The relative apparent wave velocity curve of the body wave of the test block with the maximum coarse aggregate size of 16 mm, R 2 It is an index of the degree of fit, and when it is close to 1, the fitting effect is good;

[0037] For the test block with the maximum particle size of coarse aggregate equal to 20mm, the empirical formula is as follows:

[0038]

[0039] f1 20 (·) represents the surface wave relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of 20 mm. It represents the relative apparent wave velocity curve of body wave of the test block with the maximum coarse aggregate size of 20 mm;

[0040] For the test block with the maximum particle size of coarse aggregate equal to 26.5 mm, the empirical formula is as follows:

[0041]

[0042] f1 26.5 (·) represents the surface wave relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of 26.5 mm. It represents the relative apparent wave velocity curve of body wave of the test block with the maximum coarse aggregate size of 26.5mm;

[0043] The empirical formula is interpolated and expanded, and substituted into any time-difference positioning algorithm based on a constant wave velocity to calculate the update of the apparent wave velocity as the damage evolves, thereby greatly reducing the damage location deviation of the time-difference positioning algorithm for damaged concrete components.

[0044] The apparent wave velocity updating method in step 4 includes the following process:

[0045] Process 1: Interpolation and expansion of empirical formulas;

[0046] If the component to be tested is a plate or wall component, the extended empirical formula is as follows

[0047]

[0048] If the component to be tested is a beam or column, the extended empirical formula is as follows

[0049]

[0050] Process 2: The update formula of the apparent wave velocity of the component to be tested is as follows:

[0051]

[0052] is the historical equivalent stress ratio of the component. In general, it is the ratio of the maximum historical stress of the component to the ultimate stress of the component. If the maximum historical stress of the component is unknown, the ratio of the number of years the component has been in service to the service life of the component is taken. V1 and V2 are the updated apparent wave velocities, and V is the initial wave velocity of the component to be tested, which can indirectly reflect the initial characteristics such as concrete grade and mix ratio. In process 3, the updated apparent wave velocity V1 or V2 is brought into any time-difference positioning algorithm and V in the algorithm is replaced to realize the algorithm update, thereby greatly improving the damage positioning accuracy of the damaged component.

[0053] The present invention has beneficial effects.

[0054] The present invention replaces the true wave velocity with the easily measurable apparent wave velocity, simplifies the true propagation path problem of AE into the starting point and end point problem of the path, thereby avoiding the complexity and randomness of the true propagation path, solving the drift problem of damage location accuracy with the degree of damage under the constant wave velocity assumption, and greatly reducing its positioning error. Through reasonable test scheme design, the empirical formula of the apparent wave velocity is obtained through only a simple axial compression test, and the empirical formula correction method and the apparent wave velocity inversion method based on the characteristic elements of the component are given for engineering application. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The overall framework diagram of the present invention is

[0056] Figure 2Schematic diagram of sensor arrangement of the present invention

[0057] Figure 3 The relative apparent wave velocity fitting curve diagram of the present invention is

[0058] Figure 4 The error drift of the lead-break positioning under the assumption of constant wave speed and the error after correction are shown in the figure.

[0059] Figure 5 This is a comparison diagram between the damage location point of the present invention and the actual crack morphology. DETAILED DESCRIPTION

[0060] The technical solution of the present invention is described in detail below, but the protection scope of the present invention is not limited to the implementation scheme described above.

[0061] The overall framework of the present invention is shown in Figure 1 The test block used in the present invention is a standard test block with a size of 150 mm×150 mm×150 mm.

[0062] The cement used is ordinary Portland cement, and the mix ratio is cement: sand: stone: water = 1: 0.98: 2.17: 0.41.

[0063] The maximum coarse aggregate particle sizes under the three design conditions are G1: 16mm, G2: 19mm, and G3: 26.5mm respectively. The aggregate particle sizes are continuously graded and are processed through screening, cleaning, and drying processes.

[0064] The reason for selecting the maximum particle size of coarse aggregate to distinguish the design conditions is that the maximum particle size of coarse aggregate is the concrete component element that has the greatest impact on the acoustic emission wave velocity.

[0065] After 24 hours of casting, the test block was demoulded and placed in a standard curing room for wet curing. The concrete strength grade was C40. The acoustic emission instrument used was the DS5 series full-information acoustic emission signal analyzer produced by Beijing Ruandao Technology Co., Ltd.

[0066] The sensor layout is as follows Figure 2 shown.

[0067] The loading equipment is a SYE-2000 pressure testing machine, with a loading accuracy level of level 1 and a maximum full load of 2000KN. The equivalent stress ratio during the loading process is calculated according to the following formula:

[0068]

[0069] σ c is the compressive stress value of the test block during loading, which is equal to the ratio of the real-time reading of the force sensor to the cross-sectional area of ​​the test block, f clis the ultimate compressive strength of the test block. The ultimate compressive strengths under the three design conditions are 43.13, 45.20 and 46.07 MPa respectively.

[0070] Six damage marking points were selected according to the characteristics of the damaged stage of the specimen, and their corresponding equivalent stress ratios were 0, 0.3, 0.5, 0.8, 1.0, and 1.5, respectively.

[0071] An axial compression test was carried out on the concrete cube specimen. During the loading process, when the equivalent stress ratio of the specimen reached the damage mark point, the loading was suspended and an acoustic emission lead breaking test was performed.

[0072] The apparent wave velocity is calculated by the collected lead-break signal:

[0073]

[0074] The superscript g is the number of the damage mark point, and the subscript k is the number of the spatial qualitative relationship between sensors i and j. k = 1 indicates the same-plane situation, and k = 2 indicates the different-plane situation. i is the number of the sensor next to the lead break point. Since the lead break point traverses the sensor array, i is 1, 2...n, where n is the total number of sensors in the array. j is the number of the sensor that meets the kth type of spatial qualitative relationship with sensor i, and k z is the number of combinations of sensor i and sensor j that meet the kth spatial qualitative relationship, n c is the number of repeated lead breaks at the same lead break position, S(i,j) is the actual spatial distance between sensor i and sensor j, is the time difference of the acoustic emission signal of the sensor combination measured by the cth repeated lead breaking under the zth sensor combination that meets the kth spatial qualitative relationship in the lead breaking test with the damage identification point numbered g, It is the apparent wave velocity obtained for all the broken leads that meet the kth type of spatial qualitative relationship in the broken lead test with the damage identification point numbered g.

[0075] Table 1 Calculation results of apparent wave velocity (unit: m / s)

[0076]

[0077] The relative apparent wave velocity is calculated by the following formula:

[0078]

[0079] is the relative apparent wave velocity obtained for all the lead breaks that meet the kth type of spatial qualitative relationship in the lead break test with the damage identification point numbered g, is the apparent wave velocity of the initial damage marker point under the kth type of spatial qualitative relationship.

[0080] Table 2 Calculation results of relative apparent wave velocity (dimensionless)

[0081]

[0082] Draw two-dimensional scattered points with damage markers and relative apparent wave velocity as coordinates, see Figure 3 .

[0083] The empirical formula of the two-dimensional scattered points is generated by fitting a cubic polynomial. The curve represented by the empirical formula is also plotted on Figure 3 , for the out-of-plane situation, Figure 3 When drawing scattered points in the middle, it is divided into two cases: adjacent faces and opposite faces. Figure 3 It can be seen that the difference in the positioning points of the two subdivision situations is extremely slight, so no further subdivision is performed during fitting.

[0084] The fitting formula of the cubic polynomial is as follows:

[0085]

[0086] It represents the relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of qmm under the kth type of spatial qualitative relationship. A, B, and C are the fitting coefficients.

[0087] For the test block with the maximum particle size of coarse aggregate equal to 16 mm, the fitted empirical formula is as follows:

[0088]

[0089] f1 16 (·) represents the surface wave relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of 16 mm. The relative apparent wave velocity curve of the body wave of the test block with the maximum coarse aggregate size of 16 mm, R 2 It is an index of the degree of fit, and when it is close to 1, the fitting effect is good;

[0090] For the test block with the maximum particle size of coarse aggregate equal to 20 mm, the fitted empirical formula is as follows:

[0091]

[0092] The relative apparent wave velocity curve of the surface wave of the test block with the maximum coarse aggregate size of 20 mm. It represents the body wave relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of 20mm.

[0093] For the test block with the maximum particle size of coarse aggregate equal to 26.5 mm, the fitted empirical formula is as follows:

[0094]

[0095] f1 26.5 (·) represents the surface wave relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of 26.5 mm. It represents the body wave relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of 26.5mm.

[0096] The empirical formula is interpolated and expanded. If the component to be detected is a plate or wall component, the expanded empirical formula is as follows:

[0097]

[0098] If the component to be tested is a beam or column, the extended empirical formula is as follows:

[0099]

[0100] After obtaining the extended empirical formula, the update formula of the apparent wave velocity of any component to be tested is as follows:

[0101]

[0102] is the historical equivalent stress ratio of the component. In general, it is the ratio of the maximum historical stress of the component to the ultimate stress of the component. If the maximum historical stress of the component is unknown, the ratio of the service years of the component to the service life of the component is taken. In the embodiment, Known, directly take V is the initial wave velocity of the component to be tested. In the embodiment, V is the initial wave velocity of the test block under the spatial qualitative relationship of k=2, which is 4577m / s, 4722m / s and 4825m / s under three design conditions respectively. V1 and V2 are the updated apparent wave velocities, which can indirectly reflect the initial characteristics of concrete grade, mix ratio, etc.

[0103] In order to verify the benefits of the present invention, the damaged lead signal is taken as the object, and the exhaustive method with high positioning accuracy and complex algorithm in the time difference algorithm is selected as an example. The lower limit of the positioning error of the exhaustive method under the constant wave speed assumption and the apparent wave speed correction is plotted. Figure 4 .

[0104] Depend on Figure 4 It can be seen that the error of the exhaustive method under the constant wave velocity assumption shows obvious error drift with the increase of damage degree. The error values ​​in the plastic damage stage and the secondary damage stage have reached the order of 1 / 3 of the specimen size. The error of the exhaustive method under the apparent wave velocity correction is basically stable, and the difference in positioning error with the damage degree is at the mm level.

[0105] Figure 5This is a comparison diagram of the damage location effect of the present invention and the actual crack morphology of the test block. The calculation data used is the AE signal of the entire test block destruction process. The positioning points drawn are the projections of all positioning points within a vertical distance of 37.5 mm from the YZ plane of the test block on the YZ plane. Figure 5 This indicates that the dense positioning points obtained by the present invention are well consistent with the actual crack morphology. Since the projection of the positioning points within a certain depth range is selected, the cracks of some sparse positioning points do not pass through the surface of the test block. This figure is only used for qualitative explanation.

Claims

1. A method for locating damage to concrete components based on correction of acoustic emission apparent wave velocity, characterized in that The following steps are involved: Step 1: Conduct an axial compression test on a concrete cube specimen, collect acoustic emission signals throughout the loading process, use a set of designed constants of the equivalent stress ratio as damage markers, and divide the specimen into five typical damaged stages; during the loading process, when the equivalent stress ratio of the specimen reaches the damage marker, suspend loading and conduct an acoustic emission lead-breaking test to complete the collection of damaged lead-breaking signals; after the lead-breaking test, continue loading until the next damage marker and repeat the above steps, and terminate the test after the test termination conditions are met; Step 2: Using the collected damaged lead-break signals, calculate the acoustic emission apparent wave velocity and relative apparent wave velocity under two spatial qualitative relationships of three design conditions respectively; The maximum particle sizes of coarse aggregates of the test blocks under the three design conditions are different, namely 16 mm, 20 mm, and 26.5 mm; The two spatial qualitative relationships refer to the qualitative description of the relative spatial position relationship between any two sensor combinations in the sensor array, specifically, the two sensors are located on the same surface and on different surfaces of the cubic test block, which are used to calculate the surface wave velocity and the body wave velocity respectively; The apparent wave velocity is calculated as follows The superscript g is the number of the damage mark point, and the subscript k is the number of the spatial qualitative relationship between sensors i and j; k = 1 indicates the same-plane situation, and k = 2 indicates the different-plane situation; i is the number of the sensor next to the lead break point. Since the lead break point traverses the sensor array, i is 1, 2...n, where n is the total number of sensors in the array; j is the number of the sensor that meets the kth type of spatial qualitative relationship with sensor i, k z is the number of combinations of sensor i and sensor j that meet the kth spatial qualitative relationship, n c is the number of repeated lead breaks at the same lead break position, S(i,j) is the actual spatial distance between sensor i and sensor j, is the time difference of the acoustic emission signal of the sensor combination measured by the cth repeated lead breaking under the zth sensor combination that meets the kth spatial qualitative relationship in the lead breaking test with the damage identification point numbered g, It is the apparent wave velocity obtained for all the broken leads that meet the k-th spatial qualitative relationship in the broken lead test with the damage identification point numbered g; The relative apparent wave velocity is calculated as follows: is the relative apparent wave velocity obtained for all the lead breaks that meet the kth type of spatial qualitative relationship in the lead break test with the damage identification point numbered g, is the apparent wave velocity of the initial damage marker point under the kth type of spatial qualitative relationship; Step 3: Establish two-dimensional scattered points with damage markers and relative apparent wave velocity as coordinates, and generate an empirical formula for the two-dimensional scattered points through cubic polynomial fitting; Step 4: Interpolate and expand the empirical formula, and substitute the expanded empirical formula into any time-difference positioning algorithm based on a constant wave velocity to calculate the update of the apparent wave velocity as the damage evolves, thereby greatly reducing the damage location deviation of the time-difference positioning algorithm for damaged concrete components.

2. A method for locating damage to concrete components based on acoustic emission apparent wave velocity correction according to claim 1, characterized in that: The test termination condition is to complete the one-time ultimate compressive strength f cl After loading, unload and load again to 0.5f cl ; The equivalent stress ratio is calculated according to the following formula is the equivalent stress ratio, σ c is the compressive stress value of the test block during loading, f cl is the ultimate compressive strength of the test block.

3. A method for locating damage to concrete components based on acoustic emission apparent wave velocity correction according to claim 2, characterized in that The relationship between the damage mark points, the design values ​​of the equivalent stress ratios corresponding to the damage mark points and the damage stage division of the test block is as follows: Initial damage landmark point, The test block is not loaded and is considered as a non-destructive component; The first injury landmark point is The test block is in the elastic compaction stage; The second injury landmark point is The specimen is in the elastoplastic-plastic damage stage; The third injury landmark point is The specimen is in the elastoplastic-plastic damage stage; The fourth injury landmark point is The specimen is in the plastic damage stage; The fifth injury landmark point is The specimen is in the secondary damage stage.

4. A method for locating damage to concrete components based on acoustic emission apparent wave velocity correction according to claim 2, characterized in that The step three includes the following points: The cubic polynomial fitting adopts the least squares method, and the fitting formula is as follows It represents the relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of q mm under the kth type of spatial qualitative relationship. A, B, and C are fitting coefficients. The constant 1 is set to ensure that For the test block with the maximum particle size of coarse aggregate equal to 16 mm, the empirical formula is as follows: f1 16 (·) represents the surface wave relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of 16 mm. The relative apparent wave velocity curve of the body wave of the test block with the maximum coarse aggregate size of 16 mm, R 2 It is an index of the degree of fit, and when it is close to 1, the fitting effect is good; For the test block with the maximum particle size of coarse aggregate equal to 20mm, the empirical formula is as follows: f1 20 (·) represents the relative apparent wave velocity curve of the surface wave of the test block with the maximum coarse aggregate size of 20 mm. It represents the relative apparent wave velocity curve of body wave of the test block with the maximum coarse aggregate size of 20mm; For the test block with the maximum particle size of coarse aggregate equal to 26.5 mm, the empirical formula is as follows: f1 26.5 (·) represents the surface wave relative apparent wave velocity curve of the test block with the maximum coarse aggregate size of 26.5 mm. It represents the relative apparent wave velocity curve of body wave of the test block with the maximum coarse aggregate size of 26.5mm; The empirical formula is interpolated and expanded, and substituted into any time-difference positioning algorithm based on a constant wave velocity to calculate the update of the apparent wave velocity as the damage evolves, thereby greatly reducing the damage location deviation of the time-difference positioning algorithm for damaged concrete components.

5. A method for locating damage to concrete components based on correction of acoustic emission apparent wave velocity according to claim 4, characterized in that: The apparent wave velocity updating method in step 4 The process includes: Process 1, interpolating and expanding the empirical formula; If the component to be tested is a plate or wall component, the extended empirical formula is as follows If the component to be tested is a beam or column, the extended empirical formula is as follows Process 2: The update formula of the apparent wave velocity of the component to be tested is as follows: is the historical equivalent stress ratio of the component. In general, it is the ratio of the maximum historical stress of the component to the ultimate stress of the component. If the maximum historical stress of the component is unknown, the ratio of the service years of the component to the service life of the component is taken. V1 and V2 are the updated apparent wave velocities. V is the initial wave velocity of the component to be tested, which can indirectly reflect the concrete grade and mix ratio. In process 3, the updated apparent wave velocity V1 or V2 is brought into any time difference positioning algorithm and V in the algorithm is replaced to realize the algorithm update, thereby greatly improving the damage positioning accuracy of the damaged component.

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