Electromagnetic ultrasonic longitudinal guided wave probe of an interpolation type full-coil structure and nondestructive testing method

Abstract

The invention discloses an electromagnetic ultrasonic longitudinal guided wave probe of an interpolation type full-coil structure. The probe consists of a probe framework, a plurality of solenoid electromagnet groups which are wound on the probe framework and are axially and periodically distributed, a receiving and transmitting integrated eddy current coil, a shielding lead and a surface protection layer, wherein the whole probe is of a cylindrical structure and can be directly inserted into one end of a detected pipeline to excite and receive longitudinal ultrasonic guided waves propagatingin the axial direction of the pipeline during detection. According to the invention, a plurality of solenoid electromagnets and solenoid eddy current coils which are periodically distributed in the axial direction are adopted; the winding directions of every two adjacent solenoid coils are opposite, the solenoids and the solenoid eddy current coils form a radial bias magnetic field and a circumferential eddy current which are uniform in the circumferential direction and periodically distributed in the axial direction on the wall of a measured pipe under the action of rectangular pulse current,and excitation and receiving of longitudinal guided waves propagating in the axial direction of the measured pipe are achieved based on the Lorentz force principle. The method can be used for long-distance, non-contact and coupling-agent-free guided wave detection of the non-ferromagnetic small-diameter pipeline.

Description

technical field [0001] The invention relates to ultrasonic guided wave testing, in particular to an interpolated full-coil structure electromagnetic ultrasonic guided wave probe without permanent magnets and a nondestructive testing method, which can be used for long-distance, non-contact and coupling agent-free longitudinal mode guiding of metal pipelines. wave detection. Background technique [0002] Pipelines are widely used in various important industrial fields. In some special environments, they are often accompanied by harsh working conditions such as high temperature, high pressure, and wear. During long-term operation, various defects such as corrosion and cracks are prone to occur on the pipe wall. These defects will It will cause major accidents such as pipeline cracking and material leakage in the pipeline. Therefore, non-destructive testing of pipelines is of great significance to ensure its safe operation and prevent accidents. Ultrasonic guided wave testing t...

AI Technical Summary

Problems solved by technology

However, at present, the electromagnetic ultrasonic guided wave probe mainly uses permanent magnets to provide the bias magnetic field, and the probe structure is relatively complex and the volume is large.

The outsourcing structure is mainly used for detection, that is, the probe is arranged along the outer wall of the pipeline, and due to the limited magnetic field strength of the permanent magnet, the magnetic field generated on the curved pipeline structure is unevenly distributed, resulting in low conversion efficiency and signal-to-noise ratio of the probe

At the same time, in the actual industrial environment, there are coatings or other barriers on the outer wall of the pipeline, which makes the outer wall of the pipeline unreachable

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