Damage Detection in Reinforcing Steel Bars using Ultrasonic Wave Propagation

Abstract

In the area of Non destructive testing, ultrasonic testing using wave propagation is an emerging field. Ultrasonic testing uses transmission of high frequency sound waves into a material to detect imperfections or to locate changes in material properties. The most commonly used ultrasonic testing technique is pulse echo and through transmission wherein sound is introduced into a test object and reflections (echoes) are returned to a receiver from internal imperfections. This report presents the use of above two techniques to detect the damage in reinforcing steel bars. Pulse echo is used to locate the exact position of damage and through transmission is used to know the magnitude of damage in steel rod. Negative spike pulse is used as an input signal to sending transducer at one end of the rod through Pulser/Receiver system and transmitted pulse is received at the other end by receiving transducer. The wave signatures obtained are analysed using mixed-signal oscilloscope and digitizer card. A parametric study is carried out to see the effect of change in location of damage and magnitude of damage on wave propagation through steel rods of variable length. The final results obtained were reported in the form of voltage-time curves. The characteristics of wave propagation problems are that the frequency content of the exciting force is very high. Therefore, a very fine mesh of finite elements is necessary to adequately model the problem. ABAQUS/Explicit was used as an analytical tool to model the wave propagation through steel rod.