Vibration Reduction of an Offshore Wind Turbine Situated in a Seismic Area and Subjected to Environmental loads

27 Mar 2024
Job Information

Organisation/Company

GeM - Nantes Université

Research Field

Engineering

Researcher Profile

Recognised Researcher (R2)
Leading Researcher (R4)
First Stage Researcher (R1)
Established Researcher (R3)

Country

France

Application Deadline

29 Apr 2024 - 22:00 (UTC)

Type of Contract

Temporary

Job Status

Full-time

Offer Starting Date

1 Sep 2024

Is the job funded through the EU Research Framework Programme?

Not funded by an EU programme

Is the Job related to staff position within a Research Infrastructure?

No

Offer Description

Offshore wind turbines are increasingly being installed in seismic regions to harness the abundant wind energy available there. Offshore wind turbines are thin, poorly damped structures, and are highly sensitive to vibrations induced by the simultaneous actions of wind, wave and earthquake.

The recent construction of offshore wind turbines in seismic regions requires an assessment of the impact of the combined action of wind, wave and earthquake on these structures, taking into account possible soil liquefaction. This study may be divided into three parts:

The first part of the thesis involves the establishment of two 3D calculation models (a numerical model considering the soil as a continuum and a p-y model) of an offshore wind turbine, the numerical model being the reference model which will be used to justify the relevance of the simplified p-y model and which will be used in the dynamic analyses. The aim of the two 3D models is to be able to model the seismic effect and the effect of non-alignment of the various environmental loads (wind, waves and earthquake) and to study their impact on the structural and geotechnical responses of the wind turbine.

The second part of the thesis involves the implementation of a passive inertial-type vibration reduction device (Inerter-based resonant Vibration Absorber IVA) within the 3D model developed earlier, to attenuate excessive wind, wave and earthquake vibrations. Compared with conventional damping systems, IVAs have a significantly reduced secondary mass and stroke, making them easier to install in practice.

The third part involves the development, within the 3D model developed previously, of two semi-active and active control systems for the offshore wind turbine subjected to the combined loadings of wind, wave and earthquake, where soil degradation and structural damage may occur. In this case, the passive energy dissipation system becomes inadequate for the new natural frequencies of the wind turbine. The aim of this part is therefore to evaluate the effectiveness of the proposed semi-active and active controls for controlling the dynamic responses of the wind turbine using the 3D computational model, which takes into account the soil-foundation-structure interaction and the effect of soil degradation and structural damage.

Candidate profile: The candidate should have at least an Engineering degree (or equivalent) in Civil engineering or Mechanical engineering. He should demonstrate aptitude for research. The candidate should possess a good understanding of structural dynamics and coding (MATLAB/Python) with a deep mathematical background. A candidate who demonstrates exceptional aptitude in these areas may be accorded preference. Ideally, the successful candidate should have skills in structural and geotechnical modelling, dynamic analysis and automatic control using standard finite-element software (e.g. ABAQUS, FLAC3D, OpenSees or similar), in simulating the dynamic response of structural and geotechnical systems.

Location: The PhD candidate will be located in Nantes University at the Saint-Nazaire city, France.

Funds: The thesis is funded by WEAMEC (Region Pays de la Loire and CARENE).

Salary per month: 1710 € net.

To apply to the PhD position : Interested candidates are invited to submit their applications via “Thèses en Bretagne Loire” website (https://theses.doctorat-bretagneloire.fr/sis/campagne-2024/reduction-de… ) before April 16th , 2024. The application must include (i) a CV, (ii) a letter of motivation and (iii) all grades obtained at university. Application via email are not accepted.

Funding category: Financement public/privé
WEAMEC (Région Pays de la Loire and CARENE)
PHD title: Doctorat de Mécanique/Génie Civil
PHD Country: France

Requirements
Specific Requirements

The candidate should have at least an Engineering degree (or equivalent) in Civil engineering or Mechanical engineering. He should demonstrate aptitude for research. The candidate should possess a good understanding of structural dynamics, geotechnical engineering & Control and Automation Engineering with a deep mathematical background. A candidate who demonstrates exceptional aptitude in one or more of these areas may be accorded preference. Ideally, the successful candidate should have skills in coding in MATLAB/Python, in structural modelling and dynamic analysis using standard finite-element software (e.g. ABAQUS, FLAC3D, OpenSees or similar), in simulating the dynamic response of structural and geotechnical systems.

Additional Information
Work Location(s)

Number of offers available

1

Company/Institute

GeM - Nantes Université

Country

France

City

Saint-Nazaire

Geofield

Where to apply

Website

https://www.abg.asso.fr/fr/candidatOffres/show/id_offre/121823

Contact

Website

https://gem.ec-nantes.fr/

STATUS: EXPIRED