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Evaluation method of material remaining life based on image analysis of surface microtopography features

An image analysis and topographic feature technology, applied in the direction of analyzing materials, conducting material analysis by optical means, and testing the strength of materials by applying repetitive force/pulsation force, etc. Metal fatigue mechanism is complex and other problems, to achieve the effect of simple relationship, easy engineering application and promotion

Active Publication Date: 2022-03-25
GUANGXI UNIV
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  • Summary
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

The mechanism of metal fatigue is very complicated. The current methods for evaluating the fatigue remaining life of metal materials are mainly analyzed from the macroscopic perspectives of residual stiffness, residual strength and residual ductility. Most damage models belong to empirical or semi-empirical formulas, which cannot be directly measured.
Therefore, it is difficult to define and measure fatigue damage in general

Method used

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  • Evaluation method of material remaining life based on image analysis of surface microtopography features
  • Evaluation method of material remaining life based on image analysis of surface microtopography features
  • Evaluation method of material remaining life based on image analysis of surface microtopography features

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Embodiment 1

[0028] An example of the method for evaluating the remaining life of materials based on image analysis of surface micro-topography features according to the present invention includes the following steps:

[0029] (1) Fatigue tests with controlled strain amplitudes of 0.003, 0.004, 0.005, 0.008 and 0.01 were carried out with rough ground samples until failure, and the average total fatigue life N was determined f , in order to reduce the influence of random errors, the fatigue life of multiple smooth specimens under different strain amplitudes was tested, and the average value was taken as the material life N under different strain amplitudes f , see Table 1, and the dimensions of the metal smooth round bar specimens are shown in figure 1 .

[0030] (2) Carry out N / N f (N / N f = number of pre-fatigue cycles / average total fatigue life) of pre-fatigue tests with 33.3%, 50% and 75% respectively, N / N f The relative life of the representative sample experienced N cycles of consu...

Embodiment 2

[0039] This embodiment is a test example of the method for evaluating the remaining life of a material based on the image analysis of the surface micro-topography feature of the present invention on specimens with different surface smoothness. In order to further explore the applicability and rationality of this method for evaluating the remaining life of materials for different surface finishes, two kinds of specimens with different surface finishes were tested, such as Figure 7 shown. The difference between the two types of rough grinding and fine grinding is that the surface finish of the test piece is different due to the different types of sandpaper used when the grinder is used for polishing. Figure 8 It is the surface morphology of the rough and fine ground specimens under the 500-fold optical microscope lens. By comparing the pictures, it can be seen that the initial cracks on the surface of the rough ground specimens are wider than that of the fine ground specimens....

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Abstract

A method for evaluating the remaining life of materials based on the image analysis of surface microtopography features, the metal smooth round bar specimens are subjected to different degrees of pre-fatigue tests under constant strain amplitude, followed by uniaxial tensile failure tests. Observing the specimens subjected to different cycles of uniaxial stretching through an optical microscope, the area near the necking will show obvious surface cracks, and the difference in the surface micromorphology of the material is strongly related to the fatigue cycle experienced by the metal material. Using special image analysis software to statistically analyze the surface cracks and roughness distribution of the material, the physical parameter "unit crack area" representing the fatigue cumulative damage is proposed, and the fatigue cumulative damage of the material surface is quantitatively described. A non-linear mapping between the "unit crack area" and the remaining life is established, and a method for evaluating the remaining life of materials based on monotonous breaking after tension and compression cycles and then performing apparent image processing is obtained. The method is simple in principle, easy to implement, and convenient for engineering application and popularization.

Description

technical field [0001] The invention relates to a method for analyzing the remaining life of a metal material, in particular to a method for evaluating the remaining life of a material based on image analysis of surface micro-topography features. Background technique [0002] Damage caused by metal fatigue is a common failure form in practical engineering. The assessment of the remaining life of metallic materials is particularly important due to the sudden occurrence of low-stress conditions, which often lead to unforeseen catastrophic accidents. For the case of constant load amplitude, if the material damage (material deterioration) caused by the accumulation of load alternating times can be measured, the degree of fatigue damage can be used to describe the relationship between cyclic load and life. People have done a lot of research on fatigue damage theory from different angles, trying to use different parameters to evaluate the damage degree of metal materials after al...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N21/88G01N3/32
CPCG01N3/32G01N21/8851G01N2203/0073G01N2203/0005G01N2021/8858G01N2021/8887
Inventor 张克实石车嗣刘贵龙高柳曾斌
Owner GUANGXI UNIV
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