Fatigue crack propagation real-time monitoring method based on structure surface displacement field

Abstract

The invention relates to a fatigue crack propagation real-time monitoring method based on a structure surface displacement field, which comprises the following steps: (1), building a fatigue crack propagation test platform, and clearly displaying a crack monitoring area; (2), acquiring a fatigue crack propagation image; (3), calculating a surface displacement field of the test piece; (4), realizing fatigue crack tip positioning under different cycles; (5), carrying out crack length measurement under different cycles; and (6), displaying the crack propagation path in real time. According to the invention, real-time monitoring of fatigue crack propagation can be realized, the defect that the fatigue crack propagation test needs to measure the crack length through a termination test is overcome, and the efficiency of the fatigue crack propagation test is improved; a crack length measurement error caused by a crack closing phenomenon is eliminated, and the measurement precision of a macro-scale fatigue crack test is improved to a micron dimension; the method is high in measurement precision, high in response speed, simple to operate and wide in application range.

Description

technical field [0001] The invention relates to the technical field of aerospace engines, in particular to a method for real-time monitoring of fatigue crack growth and real-time measurement of fatigue crack length based on structural surface displacement field, which is a method capable of improving the detection efficiency of material mechanical properties and improving the accuracy of material fatigue life assessment Methods. Background technique [0002] Different types of damage (such as cracks, corrosion, pits, wear, etc.) often occur in the key components of aero-engines during their service, among which fatigue cracks are one of the most common forms of damage. Carrying out structural fatigue crack growth tests and exploring the fatigue fracture law of materials is of great significance to improving the reliability and service life of structures. Among them, the fatigue crack length is an important mechanical index to study the law of fatigue growth. Therefore, it ...

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Problems solved by technology

However, during fatigue cyclic loading, the plastic zone at the crack tip will lead to small-scale yielding, resulting in the crack closure phenomenon

In the collected crack image, the gray level distribution of the closed area of ​​the crack is the same as that of the background, which makes it difficult to detect the real crack tip based on the gray level edge detection method

[0006] In summary, the traditional fatigue crack length measurement method has a complicated measurement process, and the measurement accuracy is difficult to guarantee; the existing method based on digital image processing is difficult to measure the real fatigue crack

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