Method for predicting fatigue life by utilizing weak magnetic signal of ferromagnetic material

A technology for ferromagnetic materials and fatigue life, which is applied to the analysis of materials, the application of repeated force/pulsation force to test the strength of materials, and measuring devices, etc. It can solve the problems of not being able to warn the initial damage site and not reflecting the internal mechanism of material damage.

Active Publication Date: 2020-03-24
浙大宁波理工学院
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Problems solved by technology

[0003] Non-destructive testing methods can evaluate the performance of structures or components without damaging them. Conventional non-destructive testing methods that have been widely used, such as ultrasonic and radiographic testing, have limitations. For example, only when fatigue cracks occur and have developed to a certain extent It can only be applied when the size is large, and the initial damage site cannot be warned; the work must be stopped to detect; it cannot reflect the internal mechanism of material damage, etc.

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  • Method for predicting fatigue life by utilizing weak magnetic signal of ferromagnetic material
  • Method for predicting fatigue life by utilizing weak magnetic signal of ferromagnetic material
  • Method for predicting fatigue life by utilizing weak magnetic signal of ferromagnetic material

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Embodiment Construction

[0024] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0025] Such as figure 1 , figure 2 As shown, the present invention uses the weak magnetic signal of ferromagnetic material to predict the fatigue life method, which includes the following steps.

[0026] 1. Taking the standard compact tensile (CT) sample made of steel as an example, a radial CT sample with a straight-through V-shaped notch is prepared by wire cutting technology, so that the size and surface flatness of the sample meet the specification requirements , and measure the actual size as the calculation basis, carry out final heat treatment on the standard sample according to the specification, so that the surface of the standard sample can obtain a pure initial magnetic state.

[0027] 2. Fix the sample on the fatigue testing machine, and install the weak magnetic signal test device, and mainly include the following steps.

[002...

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Abstract

The invention discloses a method for predicting fatigue life by utilizing a weak magnetic signal of a ferromagnetic material. The key point of the method is that weak magnetic signals in the fatigue crack propagation process are detected; a quantitative relation between a weak magnetic signal characteristic parameter and a fatigue crack propagation parameter is established through data analysis byutilizing a piezomagnetic signal monitored by a fixed magnetic probe and a magnetic field distribution signal detected by a movable magnetic probe, and finally a quantitative relation between the weak magnetic signal characteristic parameter and a fatigue life Nf is established. According to the method, nondestructive evaluation of the crack propagation process of the ferromagnetic material and quantitative prediction of the fatigue life can be realized.

Description

technical field [0001] The invention relates to the field of non-destructive inspection / monitoring of engineering components, in particular to a method for detecting fatigue expansion of ferromagnetic materials and quantitatively predicting fatigue life by using weak magnetic signals of ferromagnetic materials in a shielded geomagnetic field environment. Background technique [0002] Fatigue damage is the main failure mode of engineering structural components under cyclic loading. It is manifested in the initiation of fatigue cracks of components under cyclic stress and gradually extending to the critical crack length. The life of the crack initiation stage accounts for a small proportion. It is generally not considered, and the life in the crack growth stage is considered to be approximately equal to the fatigue life. Therefore, how to accurately grasp the fatigue crack growth length and growth rate of engineering components subjected to cyclic loading, and then calculate t...

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Application Information

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IPC IPC(8): G01N3/06G01N3/32
CPCG01N3/06G01N3/32
Inventor 张军毛江鸿金伟良张凯
Owner 浙大宁波理工学院
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