E/m Impedance Health Monitoring of Spot-welded Structural Joints

1 TRACT erimental results obtained during fatigue testing of a lded lap-shear structural-joint specimen are d. In these experiments, the electro-mechanical mpedance technique was used for structural health ing, damage detection, and NDE. The test ns were instrumented with piezo-electric wafer ers, and the base E/M impedance signature was over the relevant frequency range. Fatigue testing lied to initiate and propagate crack damage of ed magnitude. Preliminary tests were performed to e stiffness decrease with damage progression and g life. Then, during the health monitoring tests, the ns were continuously monitored for stiffness indicative of damage. E/M impedance signatures riodically recorded, as the damaged progressed. e data was processed, and the damage index was ed. The initiation and propagation of damage, i.e., l crack, was successfully correlated with the E/M ce measurements. Damage index values were d to increase as crack damage increases. Sensing localization principles of E/M impedance NDE were confirmed. Rejection of spurious information confirmed. Through these experiments, the E/M ce technique has been, once again, proved to be a l tool with good potential for damage detection, onitoring, and NDE.