Diagnostic method of space gridding structure node bolt loosening injury

A bolt loosening and spatial grid technology, applied in the field of bolt loosening damage diagnosis of structures, can solve the problems of simulated damage sample combination explosion, limited measured data, and reduce neural network, achieve good generalization ability, enhance practicability, reduce effect of quantity

Inactive Publication Date: 2013-05-08
BEIJING UNIV OF TECH
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AI Technical Summary

Problems solved by technology

However, due to the too many degrees of freedom of the spatial grid structure and the limited available measured data, it is almost impossible to directly use the neural network to judge the damage of the overall structure based on incomplete test information. The problem of combined explosion of damage samples, so reducing the amount of calculation of the neural network becomes the key to whether this method can be used

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  • Diagnostic method of space gridding structure node bolt loosening injury
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  • Diagnostic method of space gridding structure node bolt loosening injury

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specific Embodiment approach

[0041] see figure 1 As shown, it is a flow chart of the diagnostic method of the present invention, wherein "I" in the figure represents "primary positioning of the substructure (taking the whole structure as the research object)" and "II" represents "node positioning (taking the whole substructure as the research object)" )".

[0042] The diagnostic method mainly includes: finely modeling the bolted ball joints, and obtaining the moment-rotation angle (M―θ) curve of the bolted ball connection by analyzing the variation of the bolted ball rotational stiffness with the bending moment, and using the principle of simplification to The connection is equivalent to a straight rod;

[0043] Establish a semi-rigid model of the structure, that is, obtain a refined model of the structure;

[0044] According to the composition characteristics of the spatial grid structure, it is divided into multiple substructures according to the continuity of geometric positions, and numbered;

[00...

Embodiment 1

[0050] The experimental model of a single-layer cylindrical reticulated shell is composed of 157 nodes and 414 rods. The numerical model is as follows: Figure 4 shown. The cross-sectional area of ​​the node element in the structure is reduced due to bolt loosening damage (the inner and outer radii are reduced at the same time), but the wall thickness of the bar is kept unchanged for simulation, and its elastic modulus is assumed to be unchanged. All state calculations are completed by the finite element software ANSYS. The following are the steps of member damage identification:

[0051] (1) The bolted ball joint is modeled in detail, and the bending moment-rotation angle (M―θ) curve of the bolted ball joint is obtained by analyzing the variation of the rotational stiffness of the bolted ball with the bending moment, as shown in Figure 5 shown;

[0052] (2) Establish a semi-rigid model of the structure, that is, obtain a refined model of the structure;

[0053] (3) Divis...

Embodiment 2

[0069] From the test model of single-layer cylindrical reticulated shell in Example 1, the dynamic characteristics of the first three modes before and after bolt loosening and damage were tested by using the sinusoidal excitation method. The damage location of the test model is located in "substructure 7", such as Figure 6 As shown, the position of the node is as follows Figure 7 As shown in Fig. 1, artificially loosen the bolts at their positions to simulate damage. The establishment of training samples, input parameters, output parameters and neural network is the same as that in Embodiment 1.

[0070] The substructure positioning results of the test model bolt loosening damage diagnosis are as follows: Figure 8 Shown; the node positioning results of the bolt loosening damage diagnosis of the test model are as follows Figure 9 shown.

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Abstract

Disclosed is a diagnostic method of space gridding structure node bolt loosening injury. The diagnostic method of space gridding structure node bolt loosening injury comprises that a bolt ball node is modeling elaborately and a structural combination unit model is set up. The diagnostic method of space gridding structure node bolt loosening injury is divided into a plurality of substructures and is numbered according to a way of geometric position continuity according to composition characteristics of the space gridding structure. A structure testing point is optimizely arranged in a sensor mode and sensitivity analysis of a rod piece is carried out by frequency. Numerical value of bolt loosening injury is simulated. A training sample, an input parameter and an output parameter of a neural network is confirmed. An injury sample is input to a generalized regression neural network (GRNN) network B which is training completed. The output is an injury index of the node, namely the injury position is positioned to the existing node. The number of a training sample when the injury is accurately positioned can be greatly reduced. Practicality that the space gridding structure node bolt loosening injury is diagnosed by taking advantage of neural network technology is strengthened. Especially the diagnostic method of space gridding structure node bolt loosening injury has a prominent advantage to a large-scale space gridding structure with a plurality of the nodes.

Description

technical field [0001] The invention relates to a method for diagnosing a bolt loosening damage of a structure, in particular to a method for diagnosing a bolt loosening damage of a space grid structure node. Background technique [0002] The spatial grid structure system developed rapidly in the 1980s. Up to now, its structural form has been developing in the direction of diversification, novelty and super-large span. These large-space and super-large-space buildings require huge investment, and are often places where people gather or configure important facilities. Their safety not only maintains the lives of thousands of people, but also has significant domestic and international influence. In the structure, the nodes are the most concentrated parts of the force, which is extremely important to the safety of the overall structure. Once the nodes fail, the connected rods will lose part or all of their load-bearing functions, which may cause changes in the force transmissio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01M99/00G06F17/50
Inventor 吴金志刘才玮张毅刚
Owner BEIJING UNIV OF TECH
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