Ultrasonic nondestructive detection method of material mico-crack expanded size

Abstract

The invention provides an ultrasonic nondestructive detection method of material micro-crack expanded size. The method comprises the following steps: constructing a measurement system; manufacturing multiple reference samples, and performing repeated fatigue test on each reference sample; performing metallographic observation after each fatigue test so as to obtain a micro-crack length of each reference sample, and performing ultrasonic nonlinear Lamb wave measurement to compute a nonlinear parameter beta0 of each reference sample; obtaining a nonlinear parameter-fatigue life curve, marking micro-crack sizes corresponding to various points on the curve; performing nonlinear ultrasonic Lamb wave measurement on the to-be-tested sample to obtain the nonlinear parameter beta0, and finding outthe point corresponding to the nonlinear parameter beta0 in the above curve, and finding the length of the micro-crack corresponding to the point. A relationship of the micro-crack size and the nonlinear parameter is used for judging the micro-crack length and representing the fatigue damage, in-service equipment cannot be damaged, and the micro-crack state of the material on active can be quicklydetected at low cost.

Description

technical field [0001] The invention relates to a method for measuring the length of a material microcrack, in particular to an ultrasonic nondestructive detection method for the expansion size of a material microcrack. Background technique [0002] Planar layered solid structures are widely used in many fields such as aviation, spaceflight and information science. In the process of service, due to the influence of internal factors and external environment, the degradation of material properties will occur. The early performance degradation of materials accounts for most of the fatigue life. Under the influence of alternating load, temperature and other factors, microcracks may initiate, expand rapidly, and break suddenly, causing serious hidden dangers to the safe operation of engineering components. Therefore, effective detection and evaluation methods for early microcrack growth in materials have been developed. becomes very important. [0003] Lamb waves have been wid...

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Problems solved by technology

[0005] However, these existing literatures all focus on the characterization and evaluation of material damage, and there are few studies on the propagation of microcracks by nonlinear ultrasonic signals. The size of microcracks in the literature involved is mostly in the range visible to the naked eye. There is a study on quantitative detection and evaluation of micro-crack size by using nonlinear ultrasonic Lamb wave

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