Fretting fatigue surface crack detection method and system

Abstract

The invention discloses a fretting fatigue surface crack detection method and system, relates to the field of fatigue crack monitoring, and is used for simply and conveniently observing fatigue crackinitiation and small crack propagation of a fatigue sample. The method comprises the following steps: carrying out fatigue loading on a first part and a second part which are matched with each other for set times; separating the two first parts and the second part; laminating the mutual contact parts of the first part and the second part with binary silicone rubber to obtain a to-be-observed diaphragm; and repeating the steps until the fretting fatigue test is finished so as to obtain all to-be-observed diaphragms for fretting fatigue analysis. According to the technical scheme, the mutual contact parts of the first part and the second part are respectively laminated by adopting binary silicon rubber; binary silicone rubber laminating is adopted, the curing time is short, shrinkage is avoided after curing, and it is guaranteed that the laminated sheet can accurately reflect cracks on a test; and the method has no influence on the fatigue life of the sample.

Description

technical field [0001] The invention relates to the field of fatigue crack monitoring, in particular to a method and system for detecting fretting fatigue surface cracks. Background technique [0002] In aero-engines and aircraft, many components fail due to fretting fatigue fractures, some of which are key components, such as the tenon connection of the compressor and the turbine, the connection of the case, the connection of the disc and the shaft, etc. In order to improve the life of related components of aero-engines and reduce or avoid the occurrence of fretting fatigue failure, it is necessary to study the mechanism of fretting fatigue crack initiation and small crack growth. [0003] However, how to realize the effective monitoring of fretting fatigue crack initiation and small crack propagation of components and samples has always been a difficult problem in the industry. The inventors found that the reason is that the fretting damage occurs at the surface contact o...

AI Technical Summary

Problems solved by technology

[0005] 1. The in-situ SEM monitoring method requires prefabricated cracks on the fatigue specimen, which makes it impossible to capture crack initiation and small crack propagation

[0006] 2. The resolution of the real-time image monitoring method is low, and its accuracy cannot observe the initiation and expansion of small cracks on the surface

[0007] 3. The monitoring accuracy of the potential method and the strain gauge monitoring method is too low to effectively measure small-scale cracks

[0009] The inventors have found that this method has several disadvantages: first, the film shrinks by about 10% after it is completely air-dried

Second, the acetone used in the lamination process will have a certain impact on the fatigue life of the sample

Third, the lamination process of cellulose acetate film is very cumbersome, and it usually takes 20-30 minutes from the beginning of lamination to the complete air drying of the film; and in order to prevent the influence of small defects that occasionally appear on the surface of the film, it is usually necessary to repeat lamination many times

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