DRY-COUPLED ULTRASONIC TESTING: AN EFFECTIVE, YET UNDERUTILIZED NDE METHOD

摘要

The conversion of electrical pulses to mechanical vibrations and the conversion of returned mechanical vibrations back into electrical energy is the basis for ultrasonic testing (UT). Although there are non-contact options available for some applications (e.g. EMAT), the most widely used technique involves using a piezoelectric element to generate the ultrasound. Due to the impedance mismatch between the piezoelectric transducer and the material inspected, a liquid couplant is typically used to transmit the vibrations from the transducer into the part and receive the vibrations back into the transducer. While this technique is very efficient and popular, liquid couplants used for ultrasonic inspection have some inherent limitations and disadvantages. The liquid couplant itself is sensitive to extreme weather conditions, can be harmful to the part and environment, can make some inspections cumbersome or impossible, and their use and disposal can be expensive. An alternative method to using liquid couplant is Dry-Coupled Ultrasonic Testing (DCUT).