Detection of Water Through Steel-Lined Grout Using a Stepped-Frequency Continuous Wave Radar

Maetz, Thomas; Hagelen, Manfred; Jetten, Rainer; Moll, Jochen

doi:10.23919/eucap53622.2022.9769489

Cited by 2 publications

(3 citation statements)

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“…Te dielectric properties of the dry grout were examined in [31]. During the fatigue test the properties of the grout are not homogeneous, since it partly contains water rising in the grouted connection.…”

Section: Results Of Radar Signal Processingmentioning

confidence: 99%

“…Figure 7 presents the measurements of the input refection coefcient S 11 obtained using a vector network analyzer for the antenna characterization. Tese measurements are depicted for two diferent structures: (a) a simplifed structure discussed in [31], utilizing a Keysight M9807A vector network analyzer and (b) the fnal laboratory demonstrator structure, where a NanoVNA V2 Plus4 vector network analyzer was employed two months after the antennas were installed on the grouted connection. It is notable that the performance of the antennas slightly varies with the specifc setup and the VNA used.…”

Section: Description Of the Radarmentioning

confidence: 99%

“…Figure7: Input refection coefcient S 11 of all fve antennas used in this study; (a) on a simplifed structure described in[31] (using a Keysight M9807A vector network analyzer) and (b) on the fnal laboratory demonstrator structure (using a NanoVNA V2 Plus4 vector network analyzer).…”

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confidence: 99%

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Microwave Structural Health Monitoring of the Grouted Connection of a Monopile-Based Offshore Wind Turbine: Fatigue Testing Using a Scaled Laboratory Demonstrator

Maetz,

Kappel,

Wiemann

et al. 2023

Structural Control and Health Monitoring

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Offshore wind turbines play a significant role in the expansion of clean and renewable energy. However, their exposure to harsh marine environments and dynamic loading conditions poses significant challenges to their structural integrity. In particular, the grouted connection, serving as the crucial interface between the monopile and the transition piece, is susceptible to cracking and particle washout that can lead to destabilizing grout erosion over time. In this paper, we propose a microwave structural health monitoring (SHM) approach for damage detection in grouted connections based on a stepped-frequency continuous wave radar. The methodology exploits ultra-wideband (UWB) electromagnetic wave propagation in the frequency range from 100 MHz to 2 GHz, where the microwaves propagate along the concrete-type dielectric material guided by the surrounding steel cylinders. For the proof of concept, a scaled laboratory demonstrator was built that realistically models the dynamic loading experienced by a full-scale monopile. The structure was equipped with an UWB radar system using two transmitting and three receiving antennas directly coupled to the grout. For validation, a large number of other sensors, i.e., accelerometers, strain gauges, and acoustic emission sensors have also been installed and measured synchronously during the fatigue test. It is demonstrated here that the proposed SHM methodology offers a nondestructive and real-time method for assessing the structural integrity of the grouted connection directly, actively, and automatically. This has the potential to support predictive maintenance activities in the future.

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Section: Results Of Radar Signal Processingmentioning

confidence: 99%

Section: Description Of the Radarmentioning

confidence: 99%