Structural damage location and damage assessment method based on frequency variation

A technology of damage degree and frequency change, which is applied to the analysis of solids using sound waves/ultrasonic waves/infrasonic waves, and can solve problems such as difficult measurement of degree of freedom information, incomplete structural modal parameters, and difficulty in obtaining high-order modal information.

Inactive Publication Date: 2015-09-09
CHINA NAT OFFSHORE OIL CORP +3
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Problems solved by technology

[0011] (1) High-order modal information is required: Due to the frequency range of the exciting load and identification technology, it is generally difficult to obtain high-order modal information;
[0012] (2) Complete modal information is required: Due to the limitation of the number of sensors and the difficulty of measuring certain degrees of freedom information (such as rotational degrees of freedom), the structural modal parameters obtained by actual tests are incomplete;
[0013] (3) Formation information that needs to be normalized by mass: only the output response is used for modal parameter identification under the excitation of environmental loads, and the mode shape obtained by the identification cannot be normalized by mass

Method used

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  • Structural damage location and damage assessment method based on frequency variation
  • Structural damage location and damage assessment method based on frequency variation
  • Structural damage location and damage assessment method based on frequency variation

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Embodiment Construction

[0078] Such as figure 1 , figure 2 Shown, the present invention adopts following steps:

[0079] The first step: establish the finite element model of the undamaged structure as the reference finite element model;

[0080] Step 2: Vibration test the damaged structure and identify the m-order modal frequency of the damaged structure ω i * ( i = 1 , . . . , m ) ;

[0081] The third step: assess the damage degree of the damaged structure;

[0082] Step 4: Determining the damage location of the damaged structure.

[0083] The specific algorithm of the above steps is deduced as follows:

[0084] 1. The reference finite element model is represented by K and M, that is, the stiffness matrix and mass matrix of the undamaged structure, and its eigenvalues ​​are exp...

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Abstract

A frequency change-based structure damage positioning and damage degree evaluating method is characterized by comprising the following steps: establishing a finite element model of a non-damage structure as a reference finite element model; carrying out vibration test on a damage structure, and recognizing m-order modal frequency of the damage structure; carrying out damage degree evaluation on the damage structure; and confirming the damaged position of the damage structure. The method can accurately position the damage and evaluate the damage degree only by utilizing finite low-order frequency information before and after the damage of the structure without the need of structure vibration mode information, and is applicable to single damage and multiple damage working conditions, thus having certain practical application values.

Description

technical field [0001] The present invention relates to a method for structural damage location and damage degree assessment, in particular to a structure damage location and damage degree based on frequency change that can determine the damage location of the structure by using the low-order frequency measured by the damaged structure and evaluate the severity of the damage evaluation method. It belongs to the field of offshore oil engineering. Background technique [0002] Damage to large engineering structures such as offshore platforms is unavoidable during their service, and the only way to ensure structural safety is to determine the damage location of the structure as early as possible and assess the extent of damage for timely repair and reinforcement. [0003] At present, the detection methods for structural damage mainly include: visual inspection and ultrasonic, magnetic particle, acoustic emission and other local non-destructive testing methods. However, due to...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N29/12
Inventor 李志刚王树青李华军陈祥余王喆邹道标石湘刘福顺张敏孟元栋李英超高志强王巍巍孙贞
Owner CHINA NAT OFFSHORE OIL CORP
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