Non-Contact Ultrasonic Inspection Technology of Fillet Weldments Monitoring

It's not easy to detect the defects in fillet weldment which is widely used in various building structures and power plants just with nondestructive inspection due to its complex geometrical shape and difficult access. But it's easy to detect the cracks on the surface or just below the surface of fillet weldment heel part if surface SH-wave, among ultrasonic wave modes, is applied. The traditional ultrasound inspection using surface SH-wave is usually a contact method using piezoelectric transducer, so it's not suitable for a field application because the reliability of inspection varies depending on field environments such as couplant, contact pressure and pre-process, etc. Therefore, the necessity for non-contact ultrasound inspection is increasing. This study proposes non-contact ultrasound inspection method using EMAT (electro-magnetic acoustic transducer), and presented non-contact ultrasound inspection method for fillet weldment through experimental verification.