A non-destructive identification method for multi-defect groups based on extended finite element method
An extended finite element and identification method technology, applied in the field of multi-defect group non-destructive identification, can solve problems such as difficult to solve, achieve the effect of improving accuracy, saving calculation time, and solving multi-defect group identification
Active Publication Date: 2020-05-12
HOHAI UNIV
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Problems solved by technology
However, the existing optimization scheme can only identify several defects that are far apart, and when multiple defects that are close to each other form a defect group locally, especially when there are multiple such defect groups, the existing solution is difficult to solve
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[0036] The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings.
[0037] In order to illustrate the use process of the method of the present invention, with figure 1 Take, for example, a square plate whose side length is 1 unit length. The plate contains 3 defect groups, each defect group contains 2 defects, and the defect forms include holes, crack clusters, and holes plus cracks. In the present invention, crack clusters and holes plus cracks are approximately elliptical holes.
[0038] Step 1, on the surface of the plate such as figure 1 Sparsely arrange 9 measuring points evenly, apply such as figure 2 Load and collect point responses u m (This step is realized by numerical simulation in this example).
[0039] Step 2, establish the extended finite element numerical model of the plate, the grid is as follows figure 2 As shown, the same load as in step 1 is applied, and the model is constructed ...
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The invention discloses a multi-defect group nondestructive identification method based on an extended finite element method. The method is composed of positive analysis and negative analysis. The extended finite element method calculates discontinuous surfaces, which are independent to the internal structure, of grids; and thus the grids do not need reconstruction and calculation when the defectschange geometrically; so the extended finite element method is applied to positive analysis so as to save the time. The negative analysis is composed of three steps: (i) determining a sub-domain containing defect groups based on sparse measure points to reduce the search domain; (ii) adding measure points in the sub-domain, and identifying the defect groups one by one to determine the rough positions and sizes of defects in the defect groups; and (iii) taking the results of the step (ii) as the initial solution, and accelerating convergence to the true form of defects. The provided method hasthe advantages that on the premise that the defect number is unknown, multi-defect groups can be accurately identified; and the using amount of measure points and the iteration frequency are obviously reduced.
Description
technical field [0001] The invention belongs to the field of engineering structure safety monitoring, and in particular relates to a multi-defect group non-destructive identification method based on an extended finite element method. Background technique [0002] There are inevitably large and small defects in engineering structures, and their existence often has a significant impact on the performance of the structure, and is also the main reason for the failure of the structure. To assess the safety and reliability of a structure, it is extremely important to identify flaws in the structure using non-destructive testing methods. In the past few decades, the field of non-destructive testing has introduced technical means such as laser scanning, radiography, ultrasonic, infrared imaging, acoustic emission, and holographic imaging that can identify defects in a local area, but these Some methods are limited by strict operating environments, some cannot provide accurate defec...
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IPC IPC(8): G06T17/20G06T7/00G06N3/00
CPCG06N3/006G06T7/0004G06T17/20G06T2207/30168
Inventor 余天堂马春平
Owner HOHAI UNIV