阅读说明：本技术 一种桥式起重机主梁局部损伤定位方法 (Bridge crane girder local damage positioning method ) 是由 仲猛 童一飞 裴凤雀 于 2019-08-30 设计创作，主要内容包括：本发明提供了一种桥式起重机主梁局部损伤定位方法,包括以下步骤：步骤1,基于加速度频响分析定位发生损伤的梁段；步骤2,记识别出的损伤梁段为Q<Sub>i</Sub>,基于曲率模态进一步定位Q<Sub>i</Sub>中发生损伤的板单元。(The invention provides a bridge crane girder local damage positioning method, which comprises the following steps: step 1, analyzing and positioning a damaged beam section based on acceleration frequency response; step 2, recording the identified damaged beam section as Q i Further positioning of Q based on curvature mode i In the plate unit in which damage occurs.)

1. A bridge crane girder local damage positioning method is characterized by comprising the following steps:

step 1, analyzing and positioning a damaged beam section based on acceleration frequency response;

step 2, recording the identified damaged beam section as Q_iFurther positioning of Q based on curvature mode_iIn the plate unit in which damage occurs.

2. The method according to claim 1, wherein the step 1 comprises the following specific processes:

step 1.1, transversely dividing a crane main beam into n beam sections and performing harmonic response analysis, wherein n +1 nodes on the center lines of lower cover plates of adjacent beam sections are taken as acceleration frequency response output points;

step 1.2, forming a frequency response difference value matrix by taking the variable quantity of the acceleration frequency response amplitude a (f) of each output node before and after damage occurs as an element:

wherein n +1 is the number of output nodes, m is the number of frequency bands, and superscripts u and d indicate that the structure is in a non-damaged state and a damaged state respectively;

step 1.3, only the maximum value of each row of elements of the acceleration frequency response difference matrix delta is recorded as M_i(f_j) Setting other elements as 0, and summing the obtained matrixes according to rows to obtain a vector d representing the acceleration frequency response damage of each node_vCounting the non-zero elements of each row of the obtained matrix, and using a vector c as a counting result

Step 1.4, obtaining damage identification vector D

And step 1.5, the position of the node corresponding to the maximum value element in the D is a beam section with damage.

3. The method according to claim 1, wherein the specific process of step 2 comprises:

step 2.1, respectively setting three groups of plate unit curvature output nodes along diagonals of a lower cover plate and left and right webs of the beam section, wherein the lower cover plate is marked as B1, and the left and right webs are respectively marked as B2 and B3;

step 2.2, performing modal analysis on the structure, extracting the first three-order modal displacement data of the output node in the direction vertical to the cover plate, and calculating the node curvature modes of the three plate units by adopting a center difference method, wherein the calculation formula is as follows:

in the formula (I), the compound is shown in the specification,denotes the k-th order curvature of the node x of the plate element B (i), phi denotes the modal displacement, l_(x-1,x)And l_(x,x+1)Respectively representing the distance between the node x and the adjacent nodes;

and 2.3, determining the average value of the curvature change rate of the output points before and after the damage of each plate unit by using the curvature data in the step 2.2:

in the formula, DI represents the average curvature damage factor, k is the modal order, B (i) is the plate unit number, n is the curvature output node number, and the superscript u and d represent that the structure is in the non-damage state and the damage state respectively;

and 2.4, determining the plate unit with the maximum average curvature damage factor in the step 2.3 as a damaged unit.

Technical Field

The invention relates to a crane safety detection technology, in particular to a method for positioning local damage of a main beam of a bridge crane.

Background

With the continuous acceleration of the industrialization process, the large crane becomes an indispensable key device in the production of major industries such as machinery, shipbuilding, metallurgy and the like. The timely discovery of the early local slight damage of the structure has important significance for scientifically evaluating the health condition of the crane in service. The key of the damage positioning method based on the structural dynamic test data is the selection of measurement parameters, and the commonly used parameters with higher damage sensitivity comprise: structure natural frequency, displacement mode shape, strain mode shape and mode curvature.

The bridge crane girder is a large-span three-dimensional steel structure, and the existing method adopting direct positioning needs to arrange a large number of sensors, so that the cost of damage positioning is increased, the process is complex, and the efficiency is low.

Disclosure of Invention

The invention aims to provide a method for positioning local damage of a main beam of a bridge crane.

The technical scheme for realizing the purpose of the invention is as follows: a bridge crane girder local damage positioning method comprises the following steps:

step 1, analyzing and positioning a damaged beam section based on acceleration frequency response;

step 2, recording the identified damaged beam section as Q_iFurther positioning of Q based on curvature mode_iIn the plate unit in which damage occurs.

Further, the specific process of step 1 comprises:

step 1.1, transversely dividing a crane main beam into n beam sections and performing harmonic response analysis, wherein n +1 nodes on the center lines of lower cover plates of adjacent beam sections are taken as acceleration frequency response output points;

step 1.2, forming a frequency response difference value matrix by taking the variable quantity of the acceleration frequency response amplitude a (f) of each output node before and after damage occurs as an element:

wherein n +1 is the number of output nodes, m is the number of frequency bands, and superscripts u and d indicate that the structure is in a non-damaged state and a damaged state respectively;

step 1.3, only the maximum value of each row of elements of the acceleration frequency response difference matrix delta is recorded as M_i(f_j) Setting other elements as 0, and summing the obtained matrixes according to rows to obtain a vector d representing the acceleration frequency response damage of each node_vCounting the non-zero elements of each row of the obtained matrix, and using a vector c as a counting result

Step 1.4, obtaining damage identification vector D

And step 1.5, the position of the node corresponding to the maximum value element in the D is a beam section with damage.

Further, the specific process of step 2 includes:

step 2.1, respectively setting three groups of plate unit curvature output nodes along diagonals of a lower cover plate and left and right webs of the beam section, wherein the lower cover plate is marked as B1, and the left and right webs are respectively marked as B2 and B3;

step 2.2, performing modal analysis on the structure, extracting the first three-order modal displacement data of the output node in the direction vertical to the cover plate, and calculating the node curvature modes of the three plate units by adopting a center difference method, wherein the calculation formula is as follows:

in the formula (I), the compound is shown in the specification,denotes the k-th order curvature of the node x of the plate element B (i), phi denotes the modal displacement, l_(x-1,x)And l_(x,x+1)Respectively representing the distance between the node x and the adjacent nodes;

and 2.3, determining the average value of the curvature change rate of the output points before and after the damage of each plate unit by using the curvature data in the step 2.2:

in the formula, DI represents the average curvature damage factor, k is the modal order, B (i) is the plate unit number, n is the curvature output node number, and the superscript u and d represent that the structure is in the non-damage state and the damage state respectively;

and 2.4, determining the plate unit with the maximum average curvature damage factor in the step 2.3 as a damaged unit.

Compared with the prior art, the invention has the following advantages: the method adopts a hierarchical progressive strategy and is based on acceleration frequency response analysis and a curvature modal method to respectively analyze the damage of the girder section level and the plate unit level of the crane girder, and finally, the local damage is positioned; compared with the traditional method for directly positioning the damage, the method improves the positioning precision and reduces the number of sensors (the number of output nodes), and moreover, the calculation process of the method is simple, and a large number of optimization iteration processes are avoided, so that the method is convenient for engineering application of damage positioning.

The invention is further described below with reference to the accompanying drawings.

Drawings

FIG. 1 is a technical flowchart of a method for positioning a local damage of a main beam of a bridge crane according to the present invention;

FIG. 2 is a schematic diagram of a position of a acceleration frequency response output node in a beam section stage damage positioning process;

FIG. 3 is a schematic diagram of a beam segment level damage positioning result;

FIG. 4 is a schematic diagram of a curvature mode output node position during a board unit level damage locating process;

fig. 5 is a schematic diagram of the plate unit level damage localization results.

Detailed Description

The process of respectively performing damage location on a girder segment level and a plate unit level of a crane by adopting a hierarchical progressive strategy and based on acceleration frequency response analysis and a curvature mode method in the embodiment is shown in fig. 1, and comprises the following steps:

step S1, analyzing and positioning the beam section with damage based on the acceleration frequency response:

step S1.1, transversely dividing a crane main beam into 13 beam sections and performing harmonic response analysis, and taking 14 nodes on the center lines of lower cover plates of adjacent beam sections as acceleration frequency response output points, as shown in FIG. 2;

step S1.2, forming a matrix by taking the variable quantity of the acceleration frequency response amplitude a (f) of each output node before and after damage as an element:

wherein f is₁,f₂…f₅₅For the acceleration response output band, superscripts u and d indicate that the structure is in non-damaged and damaged states, respectivelyA wounded state;

step S1.3, the acceleration frequency response difference matrix delta in the step S1.2 is subjected to data processing:

only the maximum value of each column element of the matrix is reserved, and is marked as M_i(f_j) Setting other elements as 0, and summing the obtained matrixes according to rows to obtain a vector d representing the acceleration frequency response damage of each node_vMeanwhile, in order to determine the number of times of the maximum variation of the acceleration frequency response amplitude of each output node, counting the obtained non-zero elements of each row of the matrix, wherein the counting result is represented by a vector c, and the forms of the vectors c and d are as follows:

step S1.4, positioning the damaged beam section:

vector c and d in S1.3_vMultiplying corresponding elements to obtain a damage identification vector:

identifying the beam section with damage through the position of the node corresponding to the maximum element in the D;

step S2, the damaged beam section identified in S1 is Q₈Further localization of Q based on curvature modes, as shown in FIG. 3₈Plate unit in which damage occurs:

step S2.1, arranging curvature output nodes:

the beam section is the three-dimensional box structure of compriseing web, flange board and baffle, confirms web and lower flange board for the hot spot region that the damage takes place according to damage case statistical data, in order to improve the sensitivity of board unit curvature mode to the damage, the node arrangement mode of adoption is: three sets of curvature output nodes are provided along the diagonals of the lower deck (referenced B1) and the left and right webs (referenced B2, B3) of the beam segment, respectively, as shown in fig. 4.

Step S2.2, performing modal analysis on the structure, extracting the first three-order modal displacement data of the output node in the direction vertical to the cover plate (y direction), and calculating the node curvature modes of the three plate units by adopting a center difference method, wherein the calculation formula is as follows:

in the formula (I), the compound is shown in the specification,denotes the k-th order curvature of the node x of the plate element B (i), phi denotes the modal displacement, l_(x-1,x)And l_(x,x+1)Respectively representing the distance between the node x and the adjacent nodes;

step S2.3, determining the average value of the curvature change rate of the output points before and after the damage of each plate unit by using the curvature data in the step S2.2:

in the formula, DI represents the average curvature damage factor, k is the modal order, B (i) is the plate unit number, n is the curvature output node number, and the superscript u and d represent that the structure is in the non-damage state and the damage state respectively;

step S2.4, positioning a damaged plate unit:

and determining the plate unit with the maximum average curvature damage factor in the S2.3 as a damage unit, and completing damage positioning.

This example compares the results of localization based on the first three-order curvature modes of the structure, and the results are shown in fig. 5.

In summary, according to the bridge crane girder local damage positioning method disclosed by the invention, a level progressive strategy is adopted, and the crane girder section level and plate unit level damage analysis is respectively carried out based on the acceleration frequency response analysis and the curvature mode method, so as to finally position the local damage. The method has the advantages of less required sensors, high positioning precision and simple calculation process, and is convenient for engineering application of damage positioning.