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Method for evaluating stress concentration and fatigue damage based on feature permeability detection

A technique for fatigue damage and stress concentration, applied in the direction of material magnetic variables, etc.

Inactive Publication Date: 2012-05-02
NANCHANG HANGKONG UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] At present, the methods for early detection and evaluation of ferromagnetic specimens include metal magnetic memory detection method, Barkhausen effect detection method and acoustic emission detection method. Complete

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  • Method for evaluating stress concentration and fatigue damage based on feature permeability detection
  • Method for evaluating stress concentration and fatigue damage based on feature permeability detection
  • Method for evaluating stress concentration and fatigue damage based on feature permeability detection

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Embodiment Construction

[0017] The invention is a new detection method of stress concentration and fatigue damage, which is called metal characteristic magnetic permeability detection method here. The detection method is characterized in that the maximum differential permeability is used to detect the change of the microstructure characteristic value corresponding to the ferromagnetic test piece. The metal characteristic magnetic permeability detection method can detect the stress concentration area and fatigue damage degree of metal components; it can detect the transition status of mechanical toughness and mechanical brittleness of components; it can detect ferromagnetic materials austenite and martensite, ferrite and pearlite The phase transition process of the body; it can detect the defects and dislocation density of ferromagnetic materials; it can detect the changes of grains and grain boundaries. The detection method of the invention is characterized in that the maximum differential permeabili...

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Abstract

The invention relates to a new method for evaluating stress concentration and fatigue damage based on feature permeability detection. The microstructure feature of material is closely related with a technical magnetizing process, so that the magnetizing process can be changed by formation and change of the stress concentration, enhancement of the fatigue damage, change of the defect dislocation density, crack formation and structural phase change. The feature permeability represented by the invention is a differential permeability, which is related with the magnetizing process and the maximal magnetic field intensity. In a differential permeability matrix, a differential permeability matrix element with the maximal change rate along the microstructure variable of the material is the feature permeability corresponding to the microstructure variable. Different microstructure feature variables are corresponding to different permeability matrix elements and have different feature permeability. The feature permeability is related with specific material and microstructure change property of the specific material, and different microstructure feature changes are corresponding to different feature permeability. A circuit structure for the feature permeability detection mainly comprises an excitation coil, a detection coil, a power supply module, an A / D (Analogue / Digital) conversion module, a computer control module, a signal conditioning circuit, and the like. A specific data evaluation model is mainly dependent on the data of a low field magnetic hysteresis loop system. An excitation signal is mainly in a triangular waveform and waveform change feature in a working cycle is controlled by software programming.

Description

technical field [0001] The invention relates to a detection and evaluation method, in particular to a detection and evaluation method for stress concentration and fatigue damage based on characteristic magnetic permeability. Background technique [0002] As we all know, metal materials are widely used as stress components, and are widely used in aerospace, electric power, railways, pressure vessels and other industries. During the use of components, under the action of stress, fatigue load, internal working medium or external working environment, it is easy to generate stress at the groove, loose area, defect cavity dislocation concentration area, stress concentration area, weld seam and its heat-affected area Phenomena such as corrosion cracking or fatigue fracture cause major vicious accidents and great disasters to the country and the people. Therefore, in the non-destructive testing of components, it is of great significance to quickly, conveniently and accurately dete...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N27/72G01N27/83
Inventor 任尚坤
Owner NANCHANG HANGKONG UNIVERSITY
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