Method of applying Rayleigh waves in non-linear ultrasonic evaluation of surface damage of metal material

Abstract

The invention relates to a method of applying Rayleigh waves in non-linear ultrasonic evaluation of surface damage of a metal material. The method comprises the following steps: 1) excitation and reception of Rayleigh waves; 2) detection of reliability of a testing system; 3) measurement of non-linear coefficients when the surface of a test piece has damage of different degrees; 4) repeatable operation of test. Compared to the method of using body waves for ultrasonic nondestructive test, the non-linear ultrasonic evaluation method provided in the invention has the characteristic that Rayleigh surface waves are especially suitable for measurement of non-linear coefficients of large-scale complex plate structures. According to the invention, it is only needed to carry out excitation and measurement of supersonic waves at one side of a structure during measuring, which enables measuring to be simple and easy; the Rayleigh surface waves have advantages favorable for measuring, e.g., concentration of energy on the surface of a structure, a long propagation distance, etc.; operation is simple and easy, so the method is especially suitable for on-site detection of structural elements; effective evaluation of early damage and degeneration of mechanical properties of a material structure can be realized by using the non-linear ultrasonic method.

Description

technical field [0001] The invention relates to a nonlinear ultrasonic evaluation method for surface damage of metal materials by using Rayleigh waves. Background technique [0002] For in-service structural elements in mechanical equipment and engineering structures, under the action of external loads (including environmental effects), their life can generally be divided into three stages: early degradation of mechanical properties (including physical and chemical aging and degradation) ), initiation and accumulation of damage (microvoids and microcracks), and final fracture failure. Among them, the initiation and accumulation of damage have been widely studied on the basis of mesomechanics, damage mechanics and the combination of the two disciplines. There are now also a large number of data and a large number of models to predict crack growth under cyclic loading, environmental influences and finally failure. However, little is known about performance degradation and it...

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Problems solved by technology

However, these parameters are very insensitive to the degradation of the early mechanical properties of the material and structure

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