Acoustic guided wave detection of grounding rod corrosion: equivalent circuit model and implementation

Abstract

Acoustic pulse-echo systems, are effective for corrosion damage detection in buried individual ground rods without any need for excavation. In electric power distribution systems there are large numbers buried ground rods are used in substations to form a grounding networks that is critical for the protection of equipment and personnel working in the vicinity of the substation. Over time, these grounding rods will corrode and cease to provide adequate protection. In this work, we present an equivalent circuit model (ECM) for acoustic pulse-echo corrosion detection systems. The circuit model was used to develop a transducer configuration that effectively launches longitudinal acoustic waves that can accurately detect position and damage severity. We show that our model correctly predicts the temporal response from both undamaged rods and rods with machined simulated corrosion pits. The circuit model also accounts for loss, and the results show strong agreement with simulated soil-loss in laboratory experiments. Evidence of wave mode conversion is found in experimental data that is not captured by the model. Preliminary field measurements of copper-clad steel grounding rods are presented that show strong similarities to modeled results. This ECM is a promising basis for further development of pulse-echo systems for corrosion detection and may be useful for future tomographic analysis of field measurements.

Event identification in acoustic emission from wire breaks in pre-stressing/post-tensioning cables

“…To detect the AE signals, two piezoelectric transducers were attached to the chucks, and a laptop and a DT9816-S data acquisition system (Data Translation, model DT9816-S) with 750 kHz sampling frequency were used to record the AE signals. The transducers were developed by Durham et al [39] and had an approximately 63 kHz resonance frequency and a response range of 1 to 100 kHz. The transducer included two piezoelectric discs (STEMiNC, model SMD15T12S412) placed between two steel rods with a 12 mm radius and 20 mm length.…”

Deterioration Mechanisms and Advanced Inspection Technologies of Aluminum Windows

“…The defect or material depth can be obtained by multiplying half of the wave round-trip time by the material sound velocity. Due to the simplicity of detecting the presence and location of defects, ultrasonic pulse-echo testing techniques have been widely used for internal defects detection during aluminum corrosion damage assessments [ 71 , 72 , 73 ]. In contrast to the arrangement of transducers in the ultrasonic pulse-echo testing technique, a pair of aligned transducers, transmitter and receiver, are located on opposite sides of the detected object in the through-transmission method.…”

Sparse and Random Sampling Techniques for High-Resolution, Full-Field, BSS-Based Structural Dynamics Identification from Video

“…Here c is a constant that has been found to be approximately equal to 4 based on empirical studies [44]. Equation (4) implies that a sparse signal x can be recovered using far fewer measurements than the number of elements in x.…”

“…To date, a wide variety of techniques have been developed for structural health monitoring. These techniques include ultrasonic/acoustic-based techniques [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ], eddy-current-based techniques [ 10 , 11 , 12 ], and microwave-based techniques [ 13 , 14 , 15 ]. These technologies are promising for specific structural health monitoring applications, however, they are not readily suited to being scaled up for applications such as monitoring the structural health of an entire city.…”