Introduction To The Working Principle Of Ultrasonic Flaw Detector

At present, ultrasonic flaw detectors are widely used. Ultrasonic waves are sound waves with a frequency higher than 20 kHz, which are beyond the ability of human ears to distinguish and have strong penetrability. The so-called flaw detection mainly uses the principle that when ultrasonic waves propagate in the material medium, different material mediums will show different acoustic propagation characteristics. Routine applications such as regular inspection of the weld seam of the steel structure of the bridge can detect possible defects in the weld seam in time. Hidden danger.
Digital ultrasonic flaw detector is an industrial non-destructive testing instrument, which mainly detects, locates, evaluates and diagnoses various defects (welds, cracks, inclusions, pores, etc.) inside and on the surface of the workpiece, so as to prevent and avoid accidents. occur and have great socio-economic significance. The detection application of ultrasonic flaw detector mainly includes the detection of various materials in industry and medical treatment. Through it, people can detect whether there are bubbles, scars, cracks and other defects in industrial materials such as metals. So how do people use ultrasound to detect What about testing? Ultrasonic flaw detectors now usually emit ultrasound to the object under test (such as industrial materials, human body), and then use its reflection, Doppler effect, transmission, etc. to obtain information inside the object under test and process it to form an image. The Doppler effect method of the ultrasonic flaw detector is to use the Doppler frequency shift effect that occurs when the ultrasound encounters a moving object to obtain the characteristics of the object's motion direction and speed; the transmission method is to analyze the ultrasonic penetration through the tested object. The internal characteristics of the object can be obtained from the subsequent changes of the object, and its application is still in the development stage; Ultrasonic flaw detector mainly introduces the method of obtaining the internal characteristic information of the object through the reflection method that is currently widely used. The reflection method is based on the principle that ultrasound will be strongly reflected when it passes through the tissue interface with different acoustic impedances. Reflection will occur, and the greater the difference between the media, the greater the reflection, so we can emit ultrasonic waves that have strong penetrating power and can propagate in a straight line to an object. The ultrasonic flaw detector then receives the reflected ultrasonic waves and uses them according to The sequence and amplitude of these reflected ultrasonic waves can determine the size and distribution of various media contained in the tissue, as well as the degree of contrast between various media and other information (the sequence of reflected ultrasonic waves can reflect The distance between the reflection interface and the detection surface, and the amplitude can reflect the size of the medium, the degree of contrast difference and other characteristics), and the ultrasonic flaw detector can judge whether the object under test is abnormal.