Visualization of metal tube damage using double helical microstrip lines and self-sensing time-domain reflectometry method

The present study investigates crack visualization in a metal tube using self-sensing time-domain reflectometry with double helical microstrip lines (MSLs). The double helical MSL functions as a long-range sensing line without bend sections. It uses a differential circuit to reduce cross-talk noise. The electromagnetic field simulation results clarified that cross-talk noise is decreased when using the differential circuit. The experimental results confirmed a sudden change in the amplitude at the crack location and demonstrated that the crack was detectable. The crack existence probability obtained using the estimated value and estimation error variance from the Kriging approximation indicates a very high probability at the crack location.