Ultrasonic Lamb wave-based butt weld nondestructive testing method

Abstract

The invention concretely relates to an ultrasonic Lamb wave-based butt weld nondestructive testing method and belongs to the ultrasonic guided-wave nondestructive testing field. An excitation source is loaded at the end of a weld joint. Two piezoelectric patches are pasted on the upper surface and the lower surface of a plate symmetrically and excited. The generated weld joint guided-wave mode propagating along the weld joint has high energy and slow attenuation, and the long-distance testing problem can be solved. The testing system is shown in the figure, and composed of a function generator (1), a power amplifier (2), piezoelectric patches (3), an oblique incidence-type piezoelectric ultrasonic sensor (4), an oscilloscope (5) and a computer (6). By utilizing the testing system, when the ultrasonic Lamb wave encounters flaws of the weld joint, flaw echoes are generated. According to the time difference between the excitation waveforms and the waveforms of flaw echoes and the group velocity of the weld joint guided-wave mode, the distance from the flaws to the excitation source can be obtained, and therefore the effective locating of weld joint flaws can be achieved.

Description

technical field [0001] The invention belongs to the field of ultrasonic guided wave nondestructive testing, in particular to a nondestructive testing method for butt welds based on ultrasonic Lamb waves. Background technique [0002] With the rapid development of modern industrial technology, welding technology, one of the important means of mechanical manufacturing, has been widely used in various sectors of the manufacturing industry, such as machinery industry, nuclear industry and aerospace and other fields. In particular, it is pointed out that welding plays a very important role in the manufacture and use of pressure-bearing special equipment. For example, in the manufacture of pressure vessels, the welding workload accounts for more than 30% of the entire workload. The main component of the web in the bottom plate of the container. As an important connection part, the quality of the butt weld has a direct impact on the safety and reliability of pressure-bearing speci...

AI Technical Summary

Problems solved by technology

Scholars at home and abroad have used ultrasonic Lamb waves to detect defects in butt welds, but at present most scholars use the reflection characteristics, refraction characteristics and attenuation characteristics of ultrasonic Lamb waves to detect defects on weld seams after they are incident vertically on the weld seam , these methods are difficult to receive the detection signal due to the severe attenuation caused by the Lamb wave passing through the weld, the detection distance is short, and the detection energy is low

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