The metamaterial enhances ultrasonic testing, enabling circular wave detection for improved defect identification in industrial and medical applications.
For the first time, a joint research team led by Senior Researcher Min-woo Kweun from KIMM’s Department of Nano Devices & Displays and Distinguished Professor Yoon Young Kim from SNU’s Department of Mechanical Engineering has developed a metamaterial that can theoretically convert linear ultrasonic wave vibrations into circular vibrations and has a three-dimensional microstructure.
The team initially discovered the unique anisotropic properties of an ultrasonic medium that converts linear vibration mode ultrasonic waves, which are easily generated, into the more challenging circular vibration mode ultrasonic waves. To meet this requirement, they then designed a metamaterial with a microstructure featuring three-dimensional cylindrical holes. The team successfully measured the converted circular vibration mode ultrasound through ultrasonic experiments.
Linear vibration mode ultrasound, or shear ultrasound, is commonly used in ultrasonic non-destructive testing to detect weld and plate defects. However, when the defect’s direction is parallel to the linear vibration’s direction, its reflectivity in ultrasonic waves becomes extremely low, making it difficult to detect the returning ultrasonic signal.
In contrast, the new metamaterial technology can convert linear shear ultrasonic waves into circular shear ultrasonic waves. Additionally, generating circular vibration mode ultrasonic waves with significantly high efficiency is possible using a small number of simplified cylindrical microstructures and low-loss metal materials.
Senior Researcher Min-woo Kweun of the KIMM said, “We have developed a new ultrasonic mode capable of further improving the defect detection functionality of existing ultrasonic technologies.” He added, “We will do our utmost efforts so that this new technology can be used in industrial ultrasonic non-destructive testing and ultrasound imaging in the future.”
