Structural damage identification method and device under wave excitation based on statistical high-order moments

Abstract

This invention discloses a method and device for identifying structural damage under wave excitation based on statistical high-order moments. The method comprises: obtaining the structural dynamic response signals (displacement, velocity, or acceleration) of the structure under wave excitation in both its intact and current states; extracting the effective components of the dynamic response signals using a basis function statistical similarity method based on empirical mode decomposition and structural resonance theory; calculating the high-order moment statistics of the effective components of the dynamic response signals in both the intact and current states; normalizing the high-order moment statistics to remove the influence of the excitation magnitude; and determining whether damage exists at a specific point in the structure based on the difference in the high-order moment statistics between the intact and current states. This invention effectively addresses the problems of identifying and extracting the effective components of the response signals of complex structures under wave excitation, as well as identifying localized structural damage.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering detection, and in particular to a method and device for identifying structural damage under wave excitation based on statistical high-order moments. Background Art

[0002] The damage analysis method based on dynamic fingerprinting integrates interdisciplinary techniques such as structural vibration theory, vibration testing, and data processing, and is currently considered the most promising method for nondestructive structural testing. Furthermore, waves are a common environmental excitation for offshore structures, and using the dynamic response of wave excitation to identify damage in offshore docks has broad application prospects.

[0003] Existing damage identification methods for wharf pile foundations are mostly based on structural characteristic parameters. However, due to the inaccuracy of structural parameters obtained through wave excitation, the effect of structural damage identification is greatly weakened. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for identifying structural damage under wave excitation based on statistical high-order moments, so as to solve the problem in the prior art that it is difficult to identify local damage of offshore structures using dynamic responses under wave excitation.

[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0006] In a first aspect, a method for identifying structural damage under wave excitation is provided, comprising:

[0007] Obtain the structural dynamic response signals under wave excitation in the intact state and the current state;

[0008] The dynamic response signal is decomposed based on the empirical mode decomposition method and the rigid body resonance theory solution, and the effective components of the dynamic response signal are extracted using the basis function statistical similarity method;

[0009] Calculate the high-order moment statistics of the effective components of the dynamic response signal in the intact state and the current state;

[0010] Normalize the high-order moment statistics to obtain the normalized high-order moment statistics;

[0011] The difference in normalized high-order moment statistics between the intact state and the current state is used to determine whether there is damage at a certain point in the structure.

[0012] In some embodiments, the dynamic response signal is displacement, velocity or acceleration.

[0013] In some embodiments, the dynamic response signal is decomposed based on an empirical mode decomposition method and a rigid body resonance theory solution, including:

[0014] Assume that the structure is divided into n units with n+1 nodes, φ ji is the vibration mode of the i-th order j-th unit of the structure, and the wave circular frequency is ω f , the wave force amplitude is f i , the theoretical solutions of displacement response, velocity response, and acceleration response of the jth unit of the structure under wave excitation are:

[0015] x j (t) = A j ·sin(ω f t-η j )

[0016]

[0017]

[0018] Where: t is the observation time, x j (t) is the displacement of the jth unit at time t, is the velocity of the jth unit at time t, is the acceleration of the jth unit at time t, A j is the structural unit amplitude, η j is the intermediate parameter; for A j and η j The calculation formula is:

[0019]

[0020] B i , γ i These are all intermediate parameters, and the calculation formula is:

[0021]

[0022] in is the stiffness in mode coordinates, is the damping in mode coordinates, is the intermediate parameter; is the circular frequency of the i-th unit structure, is the mass in vibration mode coordinates;

[0023] Due to the uniformity of the displacement, velocity and acceleration, they are unified as follows:

[0024] y j (t) = C j ·sin(ω f t-λ j )

[0025] where y j (t) is called the structural dynamic response signal, C j and λj are all intermediate variables, and their formulas are:

[0026]

[0027] For the dynamic response signal y j According to the empirical mode decomposition method, there are:

[0028]

[0029] in is the eigenmode function of the jth unit, D j is the signal y j The number of eigenmode functions, r j For the aftermath.

[0030] In some embodiments, a basis function statistical similarity method is used to extract effective components of the dynamic response signal, including:

[0031] According to the theoretical solution, the frequency of the dynamic response signal is the same as the wave excitation frequency. The basis function statistical similarity method is used to extract the effective components in the dynamic response signal. Let the basis function Base(τ):

[0032] Base(τ)=sin(ω f ·τ·Δt),τ=1,…,N.

[0033] Where Δt is the signal sampling interval, τ is the sampling point number, and N is the total number of sampling points;

[0034] Define the i-th intrinsic mode function IMF of the j-th unit i j Pearson correlation coefficient with basis function

[0035]

[0036] Find the largest correlation coefficient As the effective component of the dynamic response signal under wave excitation

[0037]

[0038] in, is the value of i when the correlation coefficient is maximum.

[0039] In some embodiments, a method for calculating high-order moment statistics of effective components of a dynamic response signal includes:

[0040] Based on the effective component of the dynamic response signal Calculate the signal statistical autocorrelation function R x(τ):

[0041]

[0042] in is the mathematical expectation;

[0043] Based on R x (τ), calculate the high-order moment statistics of the effective components of the dynamic response signal

[0044]

[0045] in is the fourth-order autocorrelation function of the effective component of the dynamic response signal.

[0046] In some embodiments, normalizing the higher-order moment statistics includes:

[0047]

[0048] in is the normalized higher-order moment statistic, is the fourth-order moment of the j-th unit, that is, the high-order moment statistic; is the average value of the fourth-order moments of all n units, is the fourth-order moment variance of all n units.

[0049] In some embodiments, determining whether a point on the structure is damaged by using the difference in normalized high-order moment statistics between the intact state and the current state includes:

[0050] Constructing the high-order moment damage index HMDI based on the high-order moment statistics of intact state and current state j :

[0051] in is the normalized high-order moment index of the undamaged j-th structural unit, is the normalized higher-order moment index of the j-th structural unit after damage; HMDI j The index describes the relative change of the fourth-order moment of the unit. When HMDI j = 0, the fourth-order moment of the jth unit does not change before and after damage; HMDI j The larger the value, the greater the change in the fourth-order moment of the unit. j The value determines whether the jth unit is a damaged unit.

[0052] In a second aspect, the present invention provides a device for identifying structural damage under wave excitation, comprising a processor and a storage medium;

[0053] The storage medium is used to store instructions;

[0054] The processor is configured to operate according to the instructions to execute the steps of the method according to the first aspect.

[0055] In a third aspect, the present invention provides a storage medium having a computer program stored thereon, which implements the steps of the method described in the first aspect when executed by a processor.

[0056] The advantages of the present invention are as follows: the method provided by the present invention realizes the effective modal extraction and damage identification problems of complex dynamic response signals under wave excitation, and provides methodological support for damage detection and health assessment of offshore structures under wave excitation; it can be applied to civil engineering projects such as cross-sea bridges, offshore platforms, and wind turbine foundations, with a wide range of applications; and it can be combined with programming to realize damage identification visualization. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is an aerial view of the high-pile wharf experimental model in an embodiment of the present invention.

[0058] Figure 2 It is a cross-sectional view of the high-pile wharf experimental model in an embodiment of the present invention.

[0059] Figure 3 This is a diagram of the sensor arrangement in an embodiment of the present invention.

[0060] Figure 4 This is a diagram of damage forms in an embodiment of the present invention.

[0061] Figure 5 This is a scene diagram of the wave excitation test in an embodiment of the present invention.

[0062] Figure 6 This is a diagram of the dynamic response signal acquisition in an embodiment of the present invention.

[0063] Figure 7 It is the acceleration response of each node under the 10% damage condition in the embodiment of the present invention.

[0064] Figure 8 Extraction of effective component of node 7 under 10% damage condition in an embodiment of the present invention: (a) Original acquisition acceleration signal of node 7 under 10% damage condition; (b) Extraction of effective component of node 7 under 10% damage condition.

[0065] Figure 9 1 and 2 are identification curves under different damage conditions in the embodiment of the present invention.

[0066] Figure 10 Schematic diagram of a method flow in an embodiment of the present invention. DETAILED DESCRIPTION

[0067] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0068] In the description of the present invention, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0069] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0070] Example 1

[0071] A method for identifying structural damage under wave excitation, comprising:

[0072] Acquiring dynamic response signals of the structure under wave excitation in an intact state and a current state of the structure, wherein the dynamic response signals are displacement, velocity or acceleration;

[0073] The dynamic response signal is decomposed based on the empirical mode decomposition method and the rigid body resonance theory solution, and the effective components of the dynamic response signal are extracted using the basis function statistical similarity method;

[0074] Calculate the high-order moment statistics of the effective components of the dynamic response signal in the intact state and the current state;

[0075] Normalizing the high-order moment statistics to obtain normalized high-order moment statistics; this step is used to remove the influence of the excitation size;

[0076] The difference in normalized high-order moment statistics between the intact state and the current state is used to determine whether there is damage at a certain point in the structure.

[0077] In some embodiments, the dynamic response signal is decomposed based on the empirical mode decomposition method and the rigid body resonance theory solution, and the effective components of the dynamic response signal are extracted using the basis function statistical similarity method, including:

[0078] Assume that the structure is divided into n units with n+1 nodes, φ jiis the vibration mode of the i-th order j-th unit of the structure, and the wave circular frequency is ω f , the wave force amplitude is f i , the theoretical solutions of displacement response, velocity response, and acceleration response of the jth unit of the structure under wave excitation are:

[0079] x j (t) = A j ·sin(ω f t-η j )

[0080]

[0081]

[0082] Where: t is the observation time, x j (t) is the displacement of the jth unit at time t, is the velocity of the jth unit at time t, is the acceleration of the jth unit at time t, A j is the structural unit amplitude, η j is the intermediate parameter; for A j and η j The calculation formula is:

[0083]

[0084] B i , γ i These are all intermediate parameters, and the calculation formula is:

[0085]

[0086] in is the stiffness in mode coordinates, is the damping in mode coordinates, is the intermediate parameter; is the circular frequency of the i-th unit structure, is the mass in vibration mode coordinates;

[0087] Due to the uniformity of the displacement, velocity and acceleration, they are unified as follows:

[0088] y j (t) = C j ·sin(ω f t-λ j )

[0089] where y j (t) is called the structural dynamic response signal, C j and λ j are all intermediate variables, and their formulas are:

[0090]

[0091] For the dynamic response signal y j According to the empirical mode decomposition method, there are:

[0092]

[0093] in is the eigenmode function of the jth unit, D j is the signal y j The number of eigenmode functions, r j For the aftermath;

[0094] According to the theoretical solution, the frequency of the dynamic response signal is the same as the wave excitation frequency. The basis function statistical similarity method is used to extract the effective components in the dynamic response signal. Let the basis function Base(τ):

[0095] Base(τ)=sin(ω f ·τ·Δt),τ=1,…,N.

[0096] Where Δt is the signal sampling interval, τ is the sampling point number, and N is the total number of sampling points;

[0097] Define the i-th eigenmode function of the j-th unit Pearson correlation coefficient with basis function

[0098]

[0099] Find the largest correlation coefficient As the effective component of the dynamic response signal under wave excitation

[0100]

[0101] in, is the value of i when the correlation coefficient is maximum.

[0102] The calculation method of the high-order moment statistics of the effective components of the dynamic response signal includes:

[0103] Based on the effective component of the dynamic response signal Calculate the signal statistical autocorrelation function R x (τ):

[0104]

[0105] in is the mathematical expectation;

[0106] Based on Rx (τ), calculate the high-order moment statistics of the effective components of the dynamic response signal

[0107]

[0108] in is the fourth-order autocorrelation function of the effective component of the dynamic response signal.

[0109] In some embodiments, normalizing the higher-order moment statistics includes:

[0110]

[0111] in is the normalized higher-order moment statistic, is the fourth-order moment of the j-th unit, that is, the high-order moment statistic; is the average value of the fourth-order moments of all n units, is the fourth-order moment variance of all n units.

[0112] In some embodiments, determining whether a point on the structure is damaged by using the difference in normalized high-order moment statistics between the intact state and the current state includes:

[0113] Constructing the high-order moment damage index HMDI based on the high-order moment statistics of intact state and current state j :

[0114] in is the normalized high-order moment index of the undamaged j-th structural unit, is the normalized higher-order moment index of the j-th structural unit after damage; HMDI j The index describes the relative change of the fourth-order moment of the unit. When HMDI j = 0, the fourth-order moment of the jth unit does not change before and after damage; HMDI j The larger the value, the greater the change in the fourth-order moment of the unit. j The value determines whether the jth unit is a damaged unit.

[0115] like Figures 1 to 7 As shown in FIG, a structural damage identification method based on statistical high-order moments under wave excitation is used for pile foundation damage identification of high-pile piers. In this embodiment, the dynamic response signal is taken as an example of acceleration.

[0116] First, a high-pile pier model was made in the laboratory and placed in a wind-wave and current tank. Figure 1 、 Figure 2On the second pile on the left side of the front row, an acceleration sensor is arranged every 0.01m from top to bottom, for a total of 13 acceleration sensors, numbered 1, 2, ..., 13 from top to bottom. The sensor arrangement diagram is shown in Figure 3 , the sensor pickup direction is perpendicular to the front direction of the dock. Figure 4 The damage length is set to 0.01m, and the damage width and test conditions are as follows: the damage width is set to 4mm for 5% damage; 9mm for 10% damage; 17mm for 20% damage; and 24mm for 30% damage.

[0117] Regular wave excitation is used with a wave period of 1s, a water depth of 1m, and a wave height of 0.1m to collect the acceleration response before and after pile damage.

[0118] The identification method specifically includes the following steps:

[0119] Step 1: Obtain the acceleration responses of the structure in its current state and intact state.

[0120] Use DH5920 vibration pickup to obtain its acceleration response signal, such as Figure 7 shown.

[0121] Step 2: Decompose the dynamic response signal based on the empirical mode decomposition method and the rigid body resonance theory solution, and extract the effective components of the dynamic response signal using the basis function statistical similarity method. The wave period is 1s.

[0122] The effective amount is obtained as Figure 8 As shown:

[0123] Step 3: Calculate the high-order moment statistics of the effective components of the dynamic response signal in the intact state and the current state. Under different damage conditions, the HMDI j like Figure 9 shown.

[0124] After effective signal extraction, the HMDI index shows an obvious "peak" at node 6. This damage index can well identify local damage of the structure under regular wave excitation.

[0125] The present invention combines the analytical solution of dynamic response under wave excitation with the empirical mode decomposition method to extract the effective components of the dynamic signal under wave excitation. The constructed indicator has good sensitivity and can detect damage to high-pile piers in a timely, early and low-cost manner, proving that the method has good applicability.

[0126] Example 2

[0127] In a second aspect, this embodiment provides a device for identifying structural damage under wave excitation, including a processor and a storage medium;

[0128] The storage medium is used to store instructions;

[0129] The processor is configured to operate according to the instructions to execute the steps of the method according to embodiment 1.

[0130] Example 3

[0131] In a third aspect, this embodiment provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in Example 1 are implemented.

[0132] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0133] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0134] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0135] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0136] It is understood from common technical knowledge that the present invention may be implemented by other embodiments that do not depart from its spirit or essential features. Therefore, the embodiments disclosed above are, in all respects, merely illustrative and not exclusive. All modifications within the scope of the present invention or equivalent to the scope of the present invention are intended to be encompassed by the present invention.

Claims

1. A method for identifying structural damage under wave excitation, characterized in that: The method comprises: Obtain the structural dynamic response signals under wave excitation in the intact state and the current state; The dynamic response signal is decomposed based on the empirical mode decomposition method and the rigid body resonance theory solution, and the effective components of the dynamic response signal are extracted using the basis function statistical similarity method; Calculate the high-order moment statistics of the effective components of the dynamic response signal in the intact state and the current state; Normalize the high-order moment statistics to obtain the normalized high-order moment statistics; The difference in normalized high-order moment statistics between the intact state and the current state is used to determine whether there is damage at a certain point in the structure.

2. The method for identifying structural damage under wave excitation according to claim 1, characterized in that: The dynamic response signal is displacement, velocity or acceleration.

3. The method for identifying structural damage under wave excitation according to claim 2, characterized in that: The dynamic response signal is decomposed based on the empirical mode decomposition method and the rigid body resonance theory solution, including: Assume that the structure is divided into n units with n+1 nodes, φ ji is the vibration mode of the i-th order j-th unit of the structure, and the wave circular frequency is ω f , the wave force amplitude is f i , the theoretical solutions of displacement response, velocity response, and acceleration response of the jth unit of the structure under wave excitation are: x j (t)=A j ·sin(ω f t-h j ) Where: t is the observation time, x j (t) is the displacement of the jth unit at time t, is the velocity of the jth unit at time t, is the acceleration of the jth unit at time t, A j is the structural unit amplitude, η j is the intermediate parameter; for A j and η j The calculation formula is: B i , γ i These are all intermediate parameters, and the calculation formula is: in is the stiffness in mode coordinates, is the damping in mode coordinates, is the intermediate parameter; is the circular frequency of the i-th unit structure, is the mass in vibration mode coordinates; Due to the uniformity of the displacement, velocity, and acceleration, they are unified as follows: y j (t)=C j ·sin(ω f t-l j ) where y j (t) is called the structural dynamic response signal, C j and λ j are all intermediate variables, and their formulas are: For the dynamic response signal y j According to the empirical mode decomposition method, there are: IMF i j is the eigenmode function of the jth unit, D j is the signal y j The number of eigenmode functions, r j For the aftermath.

4. The method for identifying structural damage under wave excitation according to claim 1 or 3, characterized in that: The basis function statistical similarity method is used to extract the effective components of the dynamic response signal, including: According to the theoretical solution, the frequency of the dynamic response signal is the same as the wave excitation frequency. The basis function statistical similarity method is used to extract the effective components in the dynamic response signal. Let the basis function Base(τ): Base(τ)=sin(ω f ·τ·Δt),τ=1,…,N Where Δt is the signal sampling interval, τ is the sampling point number, and N is the total number of sampling points; Define the i-th intrinsic mode function IMF of the j-th unit i j Pearson correlation coefficient with basis function ρ{IMF i j ,Base}: Find the IMF with the largest correlation coefficient i j As the effective component of the dynamic response signal under wave excitation l=arg maxρ{IMF i j ,Base},i=1,2,…,D j Where l is the value of i when the correlation coefficient is maximum.

5. The method for identifying structural damage under wave excitation according to claim 1, characterized in that: The calculation method of the high-order moment statistics of the effective components of the dynamic response signal includes: Based on the effective component of the dynamic response signal Calculate the signal statistical autocorrelation function R x (τ): in is the mathematical expectation; Based on R x (τ), calculate the high-order moment statistics of the effective components of the dynamic response signal in is the fourth-order autocorrelation function of the effective component of the dynamic response signal.

6. The method for identifying structural damage under wave excitation according to claim 1, characterized in that: Regularize higher-order moment statistics, including: in is the normalized higher-order moment statistic, is the fourth-order moment of the j-th unit, that is, the high-order moment statistic; is the average value of the fourth-order moments of all n units, is the fourth-order moment variance of all n units.

7. The method for identifying structural damage under wave excitation according to claim 1, characterized in that: The difference between the normalized high-order moment statistics of the intact state and the current state is used to determine whether a certain point in the structure is damaged, including: Constructing the high-order moment damage index HMDI based on the high-order moment statistics of intact state and current state j : in is the normalized high-order moment index of the undamaged j-th structural unit, is the normalized higher-order moment index of the j-th structural unit after damage; HMDI j The index describes the relative change of the fourth-order moment of the unit. When HMDI j = 0, the fourth-order moment of the jth unit does not change before and after damage; HMDI j The larger the value, the greater the change in the fourth-order moment of the unit. j The value determines whether the jth unit is a damaged unit.

8. A device for identifying structural damage under wave excitation, characterized in that: including processor and storage medium; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 7.

9. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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