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Determination method for fracture toughness of actual cracked structure

A technology of fracture toughness and determination method, which is applied in the direction of testing the strength of materials by applying stable tension/pressure, which can solve problems such as difficulty in fracture toughness and achieve the effect of low cost.

Inactive Publication Date: 2016-05-25
UNIV OF SHANGHAI FOR SCI & TECH
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Problems solved by technology

[0004] The present invention aims at the difficult problem of determining the fracture toughness of the structure in the current structural integrity assessment, and proposes a method for determining the fracture toughness of the actual structure containing cracks

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  • Determination method for fracture toughness of actual cracked structure
  • Determination method for fracture toughness of actual cracked structure
  • Determination method for fracture toughness of actual cracked structure

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Embodiment Construction

[0020] The specific steps of the method for determining the fracture toughness of the actual crack-containing structure include:

[0021] 1. The fracture toughness J of the materials used in the structure C with uniform constraint parameter A p Determination of associated lines:

[0022] (1) According to the ASTME1820 standard, select a sample of a certain size as the standard sample, and then select at least one group of non-standard size samples (more accurate results can be obtained with more samples), and perform fracture mechanics on the selected samples. Experiment to measure the fracture toughness of the specimen J C .

[0023] (2) Establish a finite element model for the selected sample, and calculate the area A enclosed by the contour line of the crack tip PEEQ=0.2 (or 0.3) corresponding to the fracture toughness of different samples PEEQ .

[0024] (3) Choose the fracture toughness J measured by the above-mentioned standard sample C And the area enclosed by the...

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Abstract

The invention relates to a determination method for the fracture toughness of an actual cracked structure. The method includes: firstly determining an association line of the fracture toughness JC of the material used in the structure and a unified constraint parameter AP, then determining an association line of J integral in a cracked structure under actual working conditions and the unified constraint parameter AP, and finally drawing the two determined straight lines in one coordinate system, taking the intersection point as a structural failure point, and multiplying the vertical coordinate of the intersection point by a reference fracture toughness value to obtain a value as the actual structure's fracture toughness. The method provided by the invention realizes determination of the fracture toughness of the actual cracked structure by means of a finite element model, has the characteristics of low cost, simplicity and reliability, is convenient for use in engineering practice, and provides basis for accurate structural integrity assessment.

Description

technical field [0001] The invention relates to a structural performance evaluation method, in particular to a method for determining the fracture toughness of an actual structure containing cracks. Background technique [0002] In the current structural integrity evaluation, the safety of the actual structure is generally evaluated by the lower limit of the fracture toughness of the material measured by the standard sample with deep cracks and high restraint. However, a large number of experiments and studies have shown that the fracture toughness of materials is affected by factors such as sample / structure geometry, crack size, and loading methods. This effect is usually called "restraint effect", and the increase of restraint leads to the decrease of material fracture toughness. . In actual pressure vessels, pipelines and other structures, the defects are generally low-constraint surface shallow cracks. If the lower limit of fracture toughness measured by high-constraint...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/08
Inventor 杨杰
Owner UNIV OF SHANGHAI FOR SCI & TECH
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