Method for measuring attenuation coefficients of ultrasonic plate waves at different temperatures

Abstract

The invention discloses a method for measuring the attenuation coefficients of ultrasonic plate waves at different temperatures, which comprises the steps of 1) preparing a measurement test block containing n propagation paths with different lengths, wherein one end surface of the measurement test block is a flat surface, and the other end surface of the measurement test block is of a stepped structure; 2) adjusting the temperature of the step-shaped structure part of the measurement test block to a to-be-measured temperature and keeping the constant temperature; 3) exciting ultrasonic plate waves by utilizing an ultrasonic transducer, propagating li in the thickness of the whole measurement test block along the direction vertical to one end of the flat surface on the measurement test block, reflecting back after reaching the stepped structure to be finally received by the ultrasonic transducer, enabling the echo amplitude to be 80% full screen by adjusting the gain of an ultrasonic instrument, and recording the gain value Bi at the moment; and 4) calculating the attenuation coefficient of the ultrasonic plate waves. The method can accurately measure the attenuation coefficients ofthe ultrasonic plate waves under different workpieces and temperatures.

Description

Technical field[0001]The invention relates to a method for measuring attenuation coefficient, in particular to a method for measuring attenuation coefficient of ultrasonic plate waves at different temperatures.Background technique[0002]Ultrasonic plate waves exist in the entire inspected part and can be used to find internal and surface defects. It has important applications in ultrasonic testing, especially in the characterization of interface connection characteristics, and it plays an irreplaceable role in ultrasonic testing of sheet delamination.[0003]Surface waves can be seen as propagating on the surface of a semi-infinite solid medium. If the size of the solid medium is restricted and becomes a plate, when the wavelength of the surface wave is equivalent to the plate thickness, various types of plate waves will be generated. Plate waves can be divided into SH waves and Lamb waves. Lamb waves are the most important for ultrasonic testing. Lamb waves are divided into symmetrica...

AI Technical Summary

Problems solved by technology

[0006] At present, the method of measuring the ultrasonic attenuation coefficient is mainly to obtain the multiple reflection bottom waves of the ultrasonic wave passing through the workpiece and reaching the bottom surface at room temperature, and the ultrasonic energy loss caused by the reflection is processed by estimation, and the measurement accuracy needs to be further improved

In addition, the attenuation of ultrasonic waves increases at high temperatures, and it is difficult to meet the measurement requirements when using piezoelectric ultrasonic transducers for indirect coupling or electromagnetic ultrasonic methods. When using direct coupling methods, special high-temperature ultrasonic transducers are required, and because of the presence of couplant It makes it difficult to control the temperature uniformity of the part to be tested, so the commonly used methods are not suitable for the determination of the attenuation coefficient of ultrasonic plate waves at high temperatures

Images