Beam structure grading damage identification method and system based on additional mass block and genetic algorithm
By combining additional mass blocks and genetic algorithms, hierarchical identification of beam structure damage was achieved, solving the problems of inaccurate damage location and large computational load in existing technologies, and improving the accuracy and efficiency of damage identification.
Patent Information
- Application Number
- CN202510890359.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-11-07
AI Technical Summary
Existing technologies for beam structure damage identification suffer from inaccurate location and high computational cost, making it difficult to achieve efficient and accurate assessment of damage location and severity.
A hierarchical damage identification method based on additional mass blocks and genetic algorithms is adopted. By combining preliminary localization and secondary precise localization with genetic algorithm optimization, the precise location of the damage and the degree of damage assessment are achieved.
It improves the accuracy and computational efficiency of damage identification, reduces the amount of computation, and accurately assesses the location and extent of damage.
Smart Images
Figure CN120911167A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of beam structure damage health monitoring, and particularly relates to a beam structure hierarchical damage identification method and system based on an additional mass block and a genetic algorithm. BACKGROUND
[0002] Damage identification of a structure involves two core tasks: determination of damage location and quantification of damage degree. In a structure health monitoring system, the process is usually divided into three stages: data acquisition, damage location, and health assessment. Data acquisition obtains the vibration response signal of the structure through a sensor system and performs preprocessing; damage location identifies abnormal areas based on extracted feature indicators (such as modal parameters, frequency changes, etc.); health assessment quantifies the damage degree and evaluates the safety state of the structure by combining optimization algorithms (such as genetic algorithm, particle swarm optimization algorithm), providing a basis for maintenance decision-making.
[0003] Damage identification of a structure is a key field of engineering safety evaluation. Early research explored its feasibility through different methods. For example, Shen and Taylor proposed an optimization strategy based on the least squares method for damage detection of a simply supported beam, but this method has limitations in global damage analysis. To improve the identification accuracy, Guo Huizhong's team combined the structure frequency and strain energy data, introduced the Bayesian fusion theory, and realized the preliminary positioning of the damage area, but further optimization is needed to determine the damage degree.
[0004] On the basis of theory, some researchers have creatively applied modal strain energy to structural damage analysis, revealing damage characteristics through dynamic changes in modal parameters. Zhang Qing et al. found that the modal strain energy of a unit under a small damage is related to the damage degree in a regular manner, laying a foundation for quantitative analysis. Liu Hui's team introduced a material damage variable, quantified the strain energy dissipation rate, and proposed an expression containing a damage factor, promoting the integration of damage positioning and quantitative analysis.
[0005] In recent years, intelligent algorithms have been gradually applied in this field. For example, Miao Bingrong et al. used a particle swarm optimization algorithm to perform fine analysis of the damage area, but the initial stage needs to handle a large range of suspected areas, resulting in limited computational efficiency. However, existing methods using unit modal strain energy for damage identification are not accurate in positioning, and the damage quantification analysis has a large amount of calculation, facing challenges in balancing accuracy and computational cost. SUMMARY
[0006] The present application aims to provide a beam structure hierarchical damage identification method based on an additional mass block and a genetic algorithm to solve the problems raised in the background.
[0007] In order to achieve the above object, the application provides a beam structure hierarchical damage identification method based on an additional mass block and a genetic algorithm, comprising the following steps:
[0008] S1, collecting five-order modal vibration mode data of the damaged beam structure;
[0009] S2, using a finite element analysis software to establish a finite element model of the undamaged beam structure, and performing modal analysis on the undamaged beam structure;
[0010] S3, using a formula to respectively calculate the element modal strain energy before and after the damage of the beam structure;
[0011] S4, using a formula to calculate the average element modal strain energy change rate of the first five orders of the damaged structure, determining a first positioning result of the damage position according to the average element modal strain energy change rate, obtaining a preliminary damage area, and denoted as M1, M2,..., Mn;
[0012] S5, if the first positioning result of step S4 is a single definite damage position, the damage positioning is completed.
[0013] In a preferred embodiment, the method further comprises:
[0014] S6, if the first positioning result of step S4 is a suspected damage area, an additional mass block is applied to the beam structure to perform a second positioning on the damage position, wherein the application position of the additional mass block is the middle position of each of the preliminary damage areas M1, M2,..., Mn;
[0015] S7, for the beam structure with the applied mass block, five-order modal vibration mode data in the preliminary damage areas M1, M2,..., Mn are collected again, and the average element modal strain energy change rate of each element in the preliminary damage areas M1, M2,..., Mn is calculated according to the collected five-order modal vibration mode data;
[0016] S8, using a genetic algorithm combination optimization to determine the damage degree of the damage position.
[0017] In a preferred embodiment, in step S1, sensors are arranged on the upper part of the beam structure to collect the five-order modal vibration mode data of the damaged beam structure; in step S2, the finite element analysis software is used to establish the finite element model of the undamaged beam structure, and the modal analysis is performed on the undamaged beam structure, comprising: according to the initial design drawing of the beam structure, the material properties, Poisson's ratio, and density of the structure are input into the finite element analysis software, the finite element damage model is established, the element nodes of the beam structure are numbered, the boundary conditions are set, the modal analysis is performed, and the initial element stiffness matrix and modal displacement column vector of the structure are extracted.
[0018] In a preferred embodiment, in step S3, the unit modal strain energy before and after damage of the beam structure is respectively calculated by using the following formula:
[0019]
[0020] wherein MSE ij is the unit modal strain energy before damage, is the unit modal strain energy after damage, [K j ] is the unit stiffness matrix of the jth unit, is the i-th modal displacement column vector of the jth unit before damage, is the transpose of , is the i-th modal displacement column vector of the jth unit after damage, is the transpose of .
[0021] In a preferred embodiment, in step S4, the average unit modal strain energy change rate of the first five orders of the damaged structure is calculated by using the formula, and the first positioning result of the damage position is determined according to the average unit modal strain energy change rate, to obtain the preliminary damage area, denoted as: M1, M2,..., Mn, including:
[0022] S401, the average unit modal strain energy change rate of the first five orders is calculated by using the following formula:
[0023]
[0024] wherein, is the average unit modal strain energy change rate of the first m orders;
[0025] S402, according to the average unit modal strain energy change rate of each unit, a column chart is established, and the preliminary damage area is determined by a threshold value, and the preliminary damage area is denoted as: M1, M2,..., Mn, wherein the threshold value is set to 20%.
[0026] In a preferred embodiment, in step S6, if the suspected damage area is obtained in step S4, an additional mass block is applied to the beam structure for secondary positioning of the damage position, wherein the application position of the additional mass block is the middle position of each of the preliminary damage areas M1, M2,..., Mn, including:
[0027] S601, the application position: by applying a mass block to the simply supported beam structure, the formula is derived, and the influence of the position and size of the mass block on the modal shape of the structure is studied;
[0028] S602, applying size: three schemes of 0.5 times the mass of the damage area, 1 times the mass of the damage area, 2 times the mass of the damage area are used to apply the additional mass, and the best scheme of the size of the additional mass is obtained by comparing the schemes.
[0029] In a preferred embodiment, in step S8, the damage degree of the damage position is determined by using genetic algorithm combination optimization, including:
[0030] S801, set the initial population, variable number, variable range, crossover probability, mutation probability and maximum evolution number in Matlab, wherein the variable number corresponds to the number of damage units, the variable range corresponds to the modulus coefficient interval of the damage position, and the initialization evolution number g=1;
[0031] S802, for multiple damage cases, a combination optimization strategy is used to code the design variables of each damage position in parallel, and initial variable groups A1, A2,..., An are generated as the optimization parameters of the damage degree;
[0032] S803, call Ansys software, import the initial design variable value into Ansys damage model, calculate the average modal strain energy change rate of each order unit, and return the result to Matlab;
[0033] S804, according to the average modal strain energy change rate, the objective function F=f(J) is constructed, wherein J is the correlation function of the damage degree quantitative index and the safety threshold;
[0034] S805, based on the preset objective function, the fitness value of the current variable group is calculated, and it is judged whether the current fitness satisfies the termination condition, if yes, the optimization process is terminated, and the optimal design variable α=[α1, α2,..., αn] is output as the damage degree value;
[0035] S806, if not, the evolution number g is increased by 1, and step S802 is repeated to update the initial variable group until the termination condition is met.
[0036] In a preferred embodiment, the average modal strain energy change rate P of the damage unit calculated by Ansys is calculated by the following formula i and the initial damage positioning result P index Comparative analysis:
[0037]
[0038] Wherein, P i is the average modal strain energy change rate calculated by Ansys by inputting αi for genetic iteration, and P indexThe unit modal strain energy change rate calculated before the damage is located once, and when the two values are closest, the damage degree is closest to the actual situation.
[0039] The final output design variable optimal solution is used as the damage degree of the damage position.
[0040] In a preferred embodiment, the method comprises units for performing the following operations:
[0041] Five order modal vibration mode data of the damaged beam structure are collected;
[0042] A finite element model of the undamaged beam structure is established by using finite element analysis software, and modal analysis is performed on the undamaged beam structure;
[0043] The unit modal strain energy before and after the damage of the beam structure is calculated by using the formula;
[0044] The average unit modal strain energy change rate of the first five orders of the damaged structure is calculated by using the formula, and the one-time positioning result of the damage position is determined according to the average unit modal strain energy change rate, to obtain a preliminary damage area, which is denoted as M1, M2,..., Mn;
[0045] If the one-time positioning result is a single clear damage position, the damage positioning is completed.
[0046] In a preferred embodiment, the method further comprises units for performing the following operations:
[0047] If the one-time positioning result is a suspected damage area, an additional mass block is applied to the beam structure to perform secondary positioning of the damage position, wherein the application position of the additional mass block is the middle position of each of the preliminary damage areas M1, M2,..., Mn;
[0048] Five order modal vibration mode data in the preliminary damage areas M1, M2,..., Mn of the beam structure to which the mass block is applied are collected again, and the average unit modal strain energy change rate of each unit in the preliminary damage areas M1, M2,..., Mn is calculated according to the collected five order modal vibration mode data;
[0049] The damage degree of the damage position is determined by using genetic algorithm combination optimization.
[0050] Compared with the prior art, the method has the following beneficial effects:
[0051] The application constructs a hierarchical damage identification system based on modal strain energy theory, focusing on solving the problems of complex optimization process and low calculation efficiency in traditional damage detection methods. In the damage location stage, a two-stage judgment mechanism is adopted: first, the average element modal strain energy change rate is used to complete preliminary damage location, and then a mass block is added in the key area to implement secondary precise positioning; in the damage quantification analysis, genetic algorithm is introduced to optimize the damage reduction coefficient to accurately evaluate the structural damage degree. Through scheme comparison and case verification, the application determines the optimal mass addition scheme in the precise damage positioning stage through numerical simulation: an equivalent mass block to the mass of the initial damage area is added at the geometric center of the area to accurately locate the damage position; in the damage degree inversion process, the damage reduction coefficient is used as the optimization parameter to construct the objective function, and the improved genetic algorithm is used for iterative solution, and the calculation result is close to the actual damage degree; compared with the traditional method, the calculation amount of the hierarchical identification strategy is reduced, and the judgment results of damage position and damage degree are more accurate. BRIEF DESCRIPTION OF DRAWINGS
[0052] Figure 1 is the hierarchical damage identification method flowchart of the beam structure based on the additional mass block and genetic algorithm of the application;
[0053] Figure 2 is the simply supported beam diagram for deriving the mass block application position of the application;
[0054] Figure 3 is the finite element model diagram of the concrete beam structure of the application;
[0055] Figure 4 is the node and element number diagram of the concrete beam structure in the embodiment of the application;
[0056] Figure 5 is the table diagram of the four damage conditions set in the embodiment of the application;
[0057] Figure 6 is the result diagram of the first damage positioning in the embodiment of the application;
[0058] Figure 7 is the mass block application position diagram in the embodiment of the application;
[0059] Figure 8 is the result diagram of the secondary damage positioning in the embodiment of the application;
[0060] Figure 9 is the result diagram of the damage degree judgment in the embodiment of the application. DETAILED DESCRIPTION
[0061] The technical solutions in the embodiments of the present invention will be clearly and completely described below. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.
[0062] Example 1
[0063] like Figure 1 As shown, the beam structure graded damage identification method based on additional mass blocks and genetic algorithms of the present invention includes the following steps:
[0064] Step S1: Collect the fifth-order mode shape data of the damaged beam structure. Specifically, this includes: setting up sensors on the upper part of the beam structure to collect the fifth-order mode shape data of the damaged beam structure.
[0065] Step S2: Using Ansys finite element analysis software, establish a finite element model of the undamaged beam structure and perform modal analysis on the undamaged beam structure. Specifically, this includes: based on the initial design drawings of the beam structure, using finite element analysis software, inputting the material properties, Poisson's ratio, and density of the structure, establishing a finite element damage model, numbering the element nodes of the beam structure, setting boundary conditions, performing modal analysis, and extracting the initial element stiffness matrix and modal displacement column vector of the structure.
[0066] Step S3: Calculate the element modal strain energy of the beam structure before and after damage using the formula.
[0067] Specifically, the element modal strain energy of the beam structure before and after damage is calculated using the following formulas:
[0068]
[0069] Among them, MSE ij The modal strain energy of the unit before damage. For the element modal strain energy after damage, [K j [ ] represents the element stiffness matrix of the j-th element. Let i be the column vector of the i-th modal displacements of the j-th element before damage. for transpose, Let i be the column vector of the i-th modal displacements of the j-th element after damage. for The transpose of .
[0070] Step S4: Calculate the average element modal strain energy change rate of the first five orders of the damaged structure using the formula. Determine the initial location of the damage based on the average element modal strain energy change rate to obtain the preliminary damage area, denoted as: M1, M2, ..., Mn.
[0071] Specifically, the method comprises the following steps:
[0072] In step S401, the average unit modal strain energy rate of change of the first five orders is calculated by using the following formula:
[0073]
[0074] wherein, is the average unit modal strain energy rate of change of the first m orders;
[0075] In step S402, a column chart is established according to the average unit modal strain energy rate of change of each unit, a preliminary damage area is determined by a threshold value, and the preliminary damage area is recorded as M1, M2,..., Mn, wherein the threshold value can be set to 20%.
[0076] In step S5, if the one-time positioning result of step S4 is a single clear damage position, the damage positioning is completed.
[0077] Based on the embodiment 1, the method further comprises the following steps:
[0078] In step S6, if the one-time positioning result of step S4 is a suspected damage area, an additional mass block is applied to the beam structure to perform secondary positioning of the damage position, wherein the application position of the additional mass block is the middle position of each of the preliminary damage areas M1, M2,..., Mn; the key of step S6 is to determine the application position and the size of the applied mass:
[0079] In step S601, the application position: by applying a mass block to the simply supported beam structure, formula derivation is performed to study the influence of the position and size of the applied mass block on the modal shape of the structure, as shown in the following formula: Figure 2
[0080] For this structure, the Rayleigh quotient is:
[0081]
[0082] wherein, l is the length of the component; ω i is the natural frequency under the i-th mode, φ i (x) is the modal displacement; φ i ″(x) is the curvature modal;
[0083] When the local mass at a position x j of the beam structure is changed, if the stiffness change is ignored (i.e., δm(x)≠0, δ(EJ(x))=0), the natural frequency change of the i-th mode can be approximately expressed as:
[0084]
[0085] wherein, βij for x j The relative influence coefficient of the mass change on the i-th order frequency is
[0086]
[0087] where R mj = δ m (x j )·Δx is the mass change factor, reflecting the strength of local mass change, T i is the i-th order modal kinetic energy, combined with the expression of modal displacement φ i (x):
[0088]
[0089] After substituting the modal strain energy formula, the correlation between the unit modal strain energy and the natural frequency change can be obtained. Studies have shown that when the mass block is applied, if the mass size is unchanged (i.e. R mj is constant), the change of the unit modal strain energy is only determined by the frequency change, and the unit mass matrix M a corresponding to the position of the mass block will significantly affect the frequency change rate:
[0090]
[0091] The unit modal strain energy change rate formula is:
[0092]
[0093] Further analysis shows that the unit modal strain energy change rate MSECR j of the damaged area is more significant than that of the undamaged area. Especially when the mass block is applied at the center of the damage area, the difference between the unit modal strain energy change rates MSECR j of the two areas increases with the increase of the mass.
[0094] Step S602, size: three schemes of applying additional mass block of 0.5 times the mass of the damage area, 1 times the mass of the damage area, and 2 times the mass of the damage area are adopted respectively. Through comparison of the schemes, the best scheme of the size of the additional mass block is: applying the additional mass block of 1 times the mass of the damage area at the middle position of the damage area.
[0095] Step S7, for the beam structure with the applied mass block, the five-order modal vibration mode data in the preliminary damage areas M1, M2,..., Mn are collected again, and the average unit modal strain energy change rate of each unit in the preliminary damage areas M1, M2,..., Mn is calculated according to the collected five-order modal vibration mode data. The damage position is judged again to obtain the accurate damage position.
[0096] Step S8, the damage degree of the damage position is determined by using genetic algorithm combination optimization.
[0097] Specifically, the following steps are included:
[0098] Step S801, initial population, variable number, variable range, crossover probability, mutation probability and maximum evolution number are set in Matlab, wherein the variable number corresponds to the number of damage units, the variable range corresponds to the modulus coefficient interval of the damage position, and the initialization evolution number g=1;
[0099] Step S802, for multiple damage cases, a combination optimization strategy is used to parallel code the design variables of each damage position, and initial variable groups A1, A2,..., An are generated as damage degree optimization parameters;
[0100] Step S803, Ansys software is called, initial design variable values are imported into the Ansys damage model, average element modal strain energy change rate of each order is calculated, and the result is returned to Matlab;
[0101] Step S804, according to the average element modal strain energy change rate, a target function F=f(J) is constructed, wherein J is a correlation function of damage degree quantitative index and safety threshold;
[0102] Step S805, the fitness value of the current variable group is calculated based on the preset target function, and it is judged whether the current fitness satisfies the termination condition (such as reaching the maximum iteration number g max or the target function converges), if yes, the optimization process is terminated, and the optimal design variable α=[α1,α2,…,αn] is output as the damage degree value;
[0103] Step S806, if not, the evolution number g is incremented by 1, and step S802 is repeated to update the initial variable group until the termination condition is satisfied.
[0104] The average modal strain energy change rate P i of the damage unit calculated by Ansys is calculated by the following formula: index Comparative analysis:
[0105]
[0106] Wherein, P i is the average element modal strain energy change rate calculated by Ansys by inputting αi for genetic iteration calculation, P index is the element modal strain energy change rate calculated when the damage is located for the first time before the additional mass block is applied, and when the two values are closest, it indicates that the damage degree is closest to the actual situation;
[0107] The final output design variable optimal solution is taken as the damage degree of the damage position.
[0108] Embodiment 2
[0109] In a preferred embodiment, the method comprises the following steps:
[0110] Five-order modal shape data of the damaged beam structure is collected;
[0111] A finite element model of the undamaged beam structure is established by using finite element analysis software, and modal analysis is performed on the undamaged beam structure;
[0112] The modal strain energy of each element of the beam structure before and after damage is calculated by using the formula;
[0113] The average element modal strain energy change rate of the first five orders of the damaged structure is calculated by using the formula, and the first positioning result of the damage position is determined according to the average element modal strain energy change rate, to obtain a preliminary damage area, denoted as M1, M2,..., Mn;
[0114] If the first positioning result is a single clear damage position, the damage positioning is completed.
[0115] In a preferred embodiment, the method further comprises the following steps:
[0116] If the first positioning result is a suspected damage area, an additional mass block is applied to the beam structure for secondary positioning of the damage position, wherein the application position of the additional mass block is the middle position of each of the preliminary damage areas M1, M2,..., Mn;
[0117] The five-order modal shape data in the preliminary damage areas M1, M2,..., Mn of the beam structure with the mass block is collected again, and the average element modal strain energy change rate of each element in the preliminary damage areas M1, M2,..., Mn is calculated according to the collected five-order modal shape data;
[0118] The damage degree of the damage position is determined by using genetic algorithm combination optimization.
[0119] Embodiment 3
[0120] The method of the present application is described below by using a specific example:
[0121] First, a finite element model of the beam structure is established in the Ansys software; the elastic modulus of the model is set to 2.1×105MPa, the Poisson's ratio is 0.26, the density is 3150kg / m3, the length is 7.5m, the cross-sectional size is 0.3m×0.5m, and it is a rectangular cross-section beam. The finite element model of the beam structure is as shown in Figure 3as shown.
[0122] The unit node number of the beam structure is as shown. Figure 4
[0123] Four damage conditions are set, and damage is determined, and the four conditions are as shown. Figure 5
[0124] The beam structure is subjected to finite element analysis, and the first positioning result is obtained, as shown. Figure 6
[0125] For the suspected damage area of the first positioning result, an additional mass is applied to the beam structure, and the damage is subjected to secondary positioning, and the implementation method is referred to in Embodiments 1 and 2, and the secondary damage positioning result is as shown. Figure 7 Figure 8
[0126] The genetic algorithm combination optimization operation process is performed by joint simulation of Ansys and matlab, and the damage degree result of the damage position is obtained, as shown. Figure 9
[0127] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.
Claims
1. A method for hierarchical damage identification of beam structure based on additional mass block and genetic algorithm, characterized in that: It comprises the following steps: S1, collecting five-order modal vibration mode data of the damaged beam structure; S2, using finite element analysis software to establish a finite element model of the undamaged beam structure and performing modal analysis on the undamaged beam structure; S3, using formulas to calculate the element modal strain energy before and after the damage of the beam structure respectively; S4, using a formula to calculate the average element modal strain energy change rate of the first five orders of the damaged structure, determining the first positioning result of the damage location according to the average element modal strain energy change rate, obtaining the preliminary damage area, and recording as: M1, M2,..., Mn; S5, if the first positioning result of step S4 is a single clear damage location, the damage positioning is completed.
2. The method of claim 1, wherein the method is characterized by: It also comprises: S6, if the first positioning result of step S4 is a suspected damage area, an additional mass block is applied to the beam structure for secondary positioning of the damage location, wherein the application position of the additional mass block is the middle position of each of the preliminary damage areas M1, M2,..., Mn; S7, the five-order modal vibration mode data in the preliminary damage areas M1, M2,..., Mn are collected again for the beam structure with the mass block, and the average element modal strain energy change rate of each element in the preliminary damage areas M1, M2,..., Mn is calculated according to the collected five-order modal vibration mode data; S8, the damage degree of the damage location is determined by genetic algorithm combination optimization.
3. The method of claim 1, wherein the method is characterized by: In step S1, sensors are arranged on the upper part of the beam structure to collect five-order modal vibration mode data of the damaged beam structure; In step S2, the finite element analysis software is used to establish a finite element model of the undamaged beam structure and perform modal analysis on the undamaged beam structure, including: according to the initial design drawing of the beam structure, using the finite element analysis software to input the material properties, Poisson's ratio, density, establishing the finite element damage model, numbering the element nodes of the beam structure, setting the boundary conditions, performing modal analysis, and extracting the initial element stiffness matrix and modal displacement column vector of the structure.
4. The method of claim 3, wherein the method further comprises: In step S3, the element modal strain energy before and after the damage of the beam structure is calculated using the following formulas: where MSE ij is the modal strain energy of the element before damage, MSE ij d is the modal strain energy of the element after damage, [K j ] is the element stiffness matrix of the jth element, is the i-th modal displacement column vector of the jth element before damage, is the transpose of , is the i-th modal displacement column vector of the jth element after damage, is the transpose of .
5. The method of claim 1, wherein the method further comprises: In step S4, the average element modal strain energy change rate of the first five orders of the damaged structure is calculated using a formula, and the first positioning result of the damage location is determined according to the average element modal strain energy change rate to obtain the preliminary damage area, which is recorded as: M1, M2,..., Mn, including: S401, the average element modal strain energy change rate of the first five orders is calculated using the following formula: wherein, is the average unit modal strain energy rate of change of the preceding m orders; S402, according to the average element modal strain energy change rate of each element, a column chart is established, and the threshold value is used to determine the preliminary damage area, which is recorded as: M1, M2,..., Mn, wherein the threshold value is set to 20%.
6. The method of claim 1, wherein the method further comprises: In step S6, if a suspected damage area is obtained in step S4, an additional mass block is applied to the beam structure for secondary positioning of the damage location, wherein the application position of the additional mass block is the middle position of each of the preliminary damage areas M1, M2,..., Mn, including: S601, applying position: by applying mass blocks on the simply supported beam structure, formula derivation is conducted to study the influence of the position and size of the applied mass block on the modal shape of the structure; S602, applying size: three schemes of applying additional mass blocks, i.e. 0.5 times the mass of the damage area, 1 times the mass of the damage area and 2 times the mass of the damage area, are adopted respectively, and through scheme comparison, the optimal scheme of the size of the mass of the additional mass block is obtained.
7. The method of claim 1, wherein the method further comprises: In step S8, the damage degree of the damage position is determined by using genetic algorithm combination optimization, including: S801, setting initial population, variable number, variable range, crossover probability, mutation probability and maximum evolution number in Matlab, wherein the variable number corresponds to the number of damage units, the variable range corresponds to the modulus coefficient interval of the damage position, and the initialization evolution number g is set to 1; S802, for the case of multiple damages, a combination optimization strategy is adopted to perform parallel coding on the design variables of each damage position, and initial variable groups A1, A2,..., An are generated as the to-be-optimized parameters of the damage degree; S803, calling the Ansys software, importing the initial design variable value into the Ansys damage model, calculating the average unit modal strain energy change rate of each order, and returning the result to Matlab; S804, constructing a target function F=f(J) according to the average unit modal strain energy change rate, wherein J is the correlation function of the damage degree quantitative index and the safety threshold; S805, calculating the fitness value of the current variable group based on the preset target function, judging whether the current fitness satisfies the termination condition, if yes, terminating the optimization process and outputting the optimal design variable α=[α1, α2,..., αn] as the damage degree value; S806, if not, the evolution number g is incremented by 1, and step S802 is repeated to update the initial variable group until the termination condition is satisfied.
8. The method of claim 6, wherein the method further comprises: The average modal strain energy change rate P of the damaged element calculated by Ansys is calculated by using the following formula i The initial damage positioning result P index Comparative analysis: Wherein, P i is the average unit modal strain energy change rate obtained by genetic iteration calculation of Ansys by inputting ai, P index is the unit modal strain energy change rate calculated when the damage is located for the first time before the additional mass is applied, and when the two values are closest, it indicates that the damage degree is closest to the actual situation; The final output design variable optimal solution is used as the damage degree of the damage position.
9. A system for hierarchical damage identification of beam structures based on an attached mass and genetic algorithm, characterized in that: The method comprises the following steps: Collecting five-order modal shape data of the damaged beam structure; Using a finite element analysis software to establish a finite element model of the undamaged beam structure and performing modal analysis on the undamaged beam structure; Using a formula to calculate the unit modal strain energy before and after the damage of the beam structure respectively; Using a formula to calculate the average unit modal strain energy change rate of the first five orders of the damaged structure, determining a one-time positioning result of the damage position according to the average unit modal strain energy change rate, obtaining a preliminary damage area, and denoted as: M1, M2,..., Mn; If the one-time positioning result is a single clear damage position, the damage positioning is completed.
10. The proof-mass and genetic algorithm based beam structure hierarchical damage identification system of claim 9, wherein: The method further comprises the following steps: If the one-time positioning result is a suspected damage area, additional mass blocks are applied to the beam structure for secondary positioning of the damage position, wherein the application position of the additional mass block is the middle position of each of the preliminary damage areas M1, M2,..., Mn; For the beam structure with the mass block, five-order modal vibration mode data in the preliminary damage areas M1, M2, …, Mn are collected again, and the average unit modal strain energy change rate of each unit in the preliminary damage areas M1, M2, …, Mn is calculated according to the five-order modal vibration mode data collected again; The damage degree of the damage position is determined by genetic algorithm combination optimization.