@inproceedings{Meijers2020,
title = {Monitoring Monopile Penetration through Magnetic Stray Field Measurements},
author = {P C Meijers and A Tsouvalas and A V Metrikine},
editor = {M Papadrakakis and M Fragiadakis and C Papadimitriou},
doi = {10.47964/1120.9102.19534},
year = {2020},
date = {2020-01-01},
booktitle = {Proceedings of the XI International Conference on Structural Dynamics},
volume = {1},
pages = {1272--1280},
publisher = {EASD Procedia},
address = {Athens, Greece},
abstract = {Current methods to infer the penetration of a steel monopile during an offshore installation are rather inaccurate. Since a large number of foundation piles will be installed offshore in the coming years, a reliable technique to infer the penetration depth is vital. This paper proposes a non-contact method to monitor the pile progression into the seabed based on measurements of the magnetic stray field that permeates the air surrounding the structure, eliminating the necessity of a predefined pattern on the pile’s surface. A simple magnetisation model for the monopile is proposed from which the relative motion between the moving pile and a stationary magnetic field sensor can be extracted. Comparison between the measured and simulated stray field data show a promising correlation, providing the basis for the new non-contact monitoring technique that is applicable offshore.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}

@inproceedings{Meijers2018,
title = {Plasticity detection and quantification in monopile support structures due to axial impact loading},
author = {Peter C. Meijers and Apostolos Tsouvalas and Andrei V. Metrikine},
editor = {E. Manoach and S. Stoykov and M. Wiercigroch
},
doi = {10.1051/matecconf/201814815003},
year = {2018},
date = {2018-02-01},
booktitle = {ICoEV 2017: International Conference on Engineering Vibration},
volume = {148},
pages = {15003},
publisher = {EDP Sciences},
series = {MATEC Web Conference},
abstract = {Recent developments in the construction of offshore wind turbines have created the need for a method to detect whether a monopile foundation is plastically deformed during the installation procedure. Since measurements at the pile head are difficult to perform, a method based on measurements at a certain distance below the pile head is proposed in this work for quantification of the amount of plasticity. By considering a onedimensional rod model with an elastic-perfectly plastic constitutive relation, it is shown that the occurrence of plastic deformation caused by an impact load can be detected from these measurements. Furthermore, this plastic deformation can be quantified by the same measurement with the help of an energy balance. The effectiveness of the proposed method is demonstrated via a numerical example.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}

@inproceedings{Meijers2017b,
title = {The effect of stress wave dispersion on the drivability analysis of large-diameter monopiles},
author = {Peter C. Meijers and Apostolos Tsouvalas and Andrei V. Metrikine},
editor = {F. Vestroni and V. Gattulli and F. Romeo},
url = {http://resolver.tudelft.nl/uuid:e27fb9ab-2a9f-4245-a6e8-ead0bc55f030},
doi = {10.1016/j.proeng.2017.09.272},
year = {2017},
date = {2017-00-00},
booktitle = {EURODYN 2017: X International Conference on Structural Dynamics},
journal = {Procedia Engineering},
volume = {199},
pages = {2390--2395},
publisher = {Elsevier},
series = {Procedia Engineering},
abstract = {Due to the increasing need for energy from renewable resources, a large number of offshore wind farms are planned to be constructed in the near future. Despite the plethora of available foundation concepts for offshore wind turbines, the monopile foundation is the most widely adopted concept in practice. To predict the installation process for a monopile a so-called drivability study is performed. Such a study allows one to decide on a number of key parameters for the installation process, such as, the appropriate size of the hydraulic hammer, the number of hammer blows and energy input needed to reach the final penetration depth, and the induced stresses in the system. The latter is important for the prediction of the fatigue life of the pile.

Currently, drivability studies are based on one-dimensional wave equation models as first proposed by Smith in the 1950s. These models are valid as long as the diameter of the pile is small compared to the excited wavelengths in the structure due to the hammer impact. For large-diameter monopiles that are currently being used in the offshore wind industry, the latter condition is not met and the effect of stress wave dispersion can no longer be neglected.

In this paper the classical wave equation model is amended by an extra term which accounts for the lateral inertia of the cross-section, resulting in the so-called Rayleigh-Love rod theory. With this new model, a parametric study is performed in which the effect of stress wave dispersion on the induced stresses and the number of hammer blows needed to reach the final penetration depth are assessed. A comparison with the results obtained from the classical model is also included in order to define the applicability range of the models. It is shown that the effect of stress wave dispersion can not be neglected for a drivability study of large-diameter monopiles.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}