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Ultrasonic Flaw Detector Detection Principle
Sep 18, 2018

Ultrasonic flaw detector detection principle

Let's take a look at the following small series, the principle of ultrasonic flaw detector detection

The reflection method works on the principle that the ultrasound will reflect strongly when the interface is organized by different acoustic impedances. As we know, the sound waves are transmitted from one medium to another at the interface between the two. Reflection will occur, and the greater the difference between the media, the greater the reflection, so we can emit an ultrasonic wave that is strong and capable of linear propagation to an object. The ultrasonic flaw detector then receives the reflected ultrasonic wave and according to The order and amplitude of the reflected ultrasonic waves can determine the size and distribution of various media contained in the tissue and the degree of contrast between the various media. The ultrasonic flaw detector determines the measured Whether the object is abnormal.

In this process, there are many aspects involved, including the generation, reception, signal conversion and processing of ultrasonic waves. The method for generating ultrasonic waves is to generate an excitation electric signal through a circuit and transmit it to a crystal having a piezoelectric effect (such as quartz, lithium sulfate, etc.) to vibrate to generate ultrasonic waves; and when receiving the reflected ultrasonic waves, the piezoelectric crystal is again The electric signal is generated by the pressure of the reflected sound wave and transmitted to the signal processing circuit for a series of processing, and an image is formed behind the ultrasonic flaw detector for observation and judgment.

Here, the type of the image processing method (that is, the image into which the obtained signal is converted) can be further classified into an A-type display, an M-type display, a B-type display, a C-type display, an F-type display, and the like. The A-type display is to process the received ultrasonic signal into a waveform image. According to the shape of the waveform, it can be seen whether there are abnormalities and defects in the measured object, and how large, etc., the ultrasonic flaw detector is mainly used for industrial detection; The display is to perform a one-dimensional "spatial multi-point motion timing diagram" by illuminating the detected information processed by the luminance, and is suitable for observing an internal moving object, an ultrasonic flaw detector such as a moving organ, an artery, etc. The B-type display is a two-dimensional "anatomical image" that combines a plurality of side-by-side luminance-detected detection information to reflect the internal tomographic section of the measured object (the B-mode used in hospitals is made using this principle) The ultrasonic flaw detector is suitable for observing objects that are static inside; the C-type display and the F-type display are now used less. Ultrasonic flaw detector detection can not only be very accurate, but also more convenient and faster than other detection methods, and it will not cause harm to the detection object and the operator. Therefore, it is more and more popular and popular. Development prospects.