Ultrasonic testing-NDT

There are many uses for sound in the world today. Performers can take advantage from a better understanding of sound, architects needs to understand sound to design effective auditoriums, and many new types of technology apply sound recognition. Another use of sound is in the area of science called Nondestructive testing, or NDT.

Ultrasonic testing (UT) has been practiced for many decades. Initial rapid developments in instrumentation encouraged by the technological advances from the 1950’s continue today. Through the 1980’s and continuing through the present, computers have provided technicians with smaller and more rugged instruments with greater capabilities.

NDT ultrasonic Testing uses high frequency sound energy to conduct examinations and make measurements. This type of inspection can be used for flaw detection, dimensional measurements, material characterization, and more. In industrial applications, ultrasonic testing is commonly used on metals, plastics, composites, and ceramics. The only common engineering materials that are not suitable for ultrasonic testing with normal tools are wood and paper products. Ultrasonic technology is also usually used in the biomedical field for diagnostic imaging and medical research.

In the late 1940s, researchers in Japan pioneered the use of ultrasonic testing in medical diagnostics using early B-scan equipment that provided a two-dimensional profile image of tissue layers. By the 1960s, early versions of medical scanners were being used to detect and outline tumors, gallstones, and similar conditions. In the 1970s, the introduction of precision thickness gages brought ultrasonic testing to a wide variety of manufacturing operations that required thickness measurement of parts in situations where there was access to only one side, and corrosion gages came into wide use for measurement of remaining wall thickness in metal pipes and tanks.

Ultrasonic is also used to detect anomalies in weld inspections. These are typically performed using a straight beam transducer in conjunction with an angle beam transducer and wedge. A straight beam transducer, producing a longitudinal wave at normal incidence into the test piece, is first used to locate any laminations in or near the heat-affected zone. This is important because an angle beam transducer may not be able to provide a return signal from a laminar flaw.

Ultrasonic Inspection is a very useful and versatile NDT method. Ultrasonic testing is completely nondestructive. The test piece does not have to be cut or exposed to damaging chemicals. Access to only one side is required, unlike measurement with mechanical thickness tools like calipers and micrometers. There are no potential health hazards related to ultrasonic testing, unlike radiography. When a test has been properly set up, results are highly repeatable and reliable.

By the other hand Ultrasonic inspection has potential limitations too. This type of inspection requires a trained operator who can set up a test with the aid of appropriate reference standards and properly interpret the results. Inspections of some complex geometry may be challenging. Ultrasonic thickness gages must be calibrated with respect to the material being measured, and applications needing a wide range of thickness measurement or measurement of acoustically various materials may require multiple setups. Ultrasonic thickness gages are more expensive than mechanical measurement devices.

There are many uses for sound in today’s modern world ranging from music, design, and medicine. Sound can also be used in the inspection of materials. This use of sound is used in the field of NDT; or Nondestructive Testing. By using ultrasonic waves, skilled inspectors are able to find minute faults in materials that can later prove disastrous for any project those materials are in. Ultrasonic can help save lives by finding these defects.