A Nonlinear Torsional Mode Ultrasonic Guided Wave Method for Micro-Damage Evaluation of Metal Tubes

Abstract

The invention discloses a nonlinear torsion modal ultrasonic guided-wave method used for evaluating metal circular tube microdamage. Through a stimulation energy converter, single torsion modal ultrasonic guided-wave is stimulated in the circular tube; when the torsion modal ultrasonic guided-wave is spread in the circular tube, the torsion modal ultrasonic guided-wave and the microdamage of the circular tube mutually act to generate third harmonic with an accumulation effect; through a receiving energy converter, a fundamental frequency signal and third harmonic generated by the tube microdamage are received; an amplitude A1 and a third harmonic amplitude A3 of the fundamental frequency signal are obtained, an equivalent three-order nonlinear sound parameter [gamma'] is calculated, and the nonlinear ultrasonic guided-wave evaluation of the microdamage of the circular tube is evaluated. The nonlinear torsion modal ultrasonic guided-wave has a third harmonic accumulation effect on any point on a frequency dispersion curve, and therefore, the restriction that nonlinear longitudinal modal guided-wave only has the accumulation effect on certain points on the frequency dispersion curveis overcome. The damage states of circular tube construction members / materials can be effectively detected and evaluated, detection speed is high, detection cost is low, and detection accuracy is high.

Description

technical field [0001] The invention relates to a method for micro-damage evaluation of metal circular tubes, in particular to a nonlinear torsional mode ultrasonic guided wave method for micro-damage evaluation of metal circular tubes. Background technique [0002] Metal round pipe structures are widely used in various industries, such as oil pipelines, buried water pipes, etc. These circular tube structures are easily affected by various external factors during actual use. Under the repeated action of these external factors for a long time, the circular tube structure will generally appear in the stages of material performance degradation, microcrack generation, crack propagation and structural fracture. Studies have shown that the performance degradation of materials and the generation of microcracks account for a large proportion of the structural life cycle. For example, for fatigue damage, the microscopic damage stages such as performance degradation and microcracks w...

AI Technical Summary

Problems solved by technology

Due to the limited number of fundamental frequency mode points satisfying the phase velocity matching condition and discretely distributed on the dispersion curve, the methods proposed in Chinese patent: CN 102866202 A and Chinese patent: CN 103969339 A have many deficiencies, and are subject to many restrictions

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