Defect location method for t-shaped stringers based on ultrasonic guided waves

Abstract

The invention discloses a method for positioning defects of a T-type stringer on the basis of ultrasonic guided waves. The method comprises the following specific steps of: (S1) analyzing by the semi-analytical finite element method theory to obtain a guided-wave characteristic propagating on the T-type stringer; (S2) selecting all frequencies and modes for detection by frequency dispersion curvesand wave structures; (S3) carrying out excitation and reception of guided waves on the ends of the T-type stringer along guided-wave sensors arranged along the circumferential direction, wherein thesensors are fixed by clamps and are coupled with the surface of the stringer; (S4) using signal excitation equipment to generate guided-wave signals with the selected frequencies; (S5) determining longitudinal positions of the damages by time difference between peak values of echo signals and excitation signals according to the excitation frequency and the mode wave velocity selected every time, and determining positions of horizontal defects according to detection results of all frequencies and modes with different horizontal-defect sensitivity.

Description

technical field [0001] The invention relates to the field of stringer non-destructive testing, in particular to a T-shaped stringer defect location method based on ultrasonic guided waves. Background technique [0002] Stringer structures are widely used in various aerospace vehicle structures, such as aircraft wings, fuselages and rocket bodies. The stringer structure plays the role of supporting the skin in the aircraft, and bears axial tension and compression, bending, shearing and torsional loads caused by gravity, thrust, aerodynamic resistance, etc., and may also bear stress and fatigue loads caused by low temperature. Complicated load conditions are very likely to cause defects in the stringers, and the defects will affect the reliability of the stringers, and even cause the structure of the stringers to break, leading to the failure of the aircraft structure. [0003] On November 5, 2010, NASA announced that the launch mission of the Discovery space shuttle STS-133 ...

AI Technical Summary

Problems solved by technology

At present, a variety of detection technologies can theoretically be used for the defect location of stringer structures, but the traditional point-by-point scanning method takes a long time and costs a lot

In addition, most of the stringer structures are arranged in invisible aircraft structures that are difficult to operate in a wide range, which increases the difficulty of detection

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