Model reduction for the design of steel wire ropes in the mooring line of a floating wind turbine

The ongoing development of floating wind energy requires ensuring the fatigue life of the structure components. Steel wire ropes are often employed in the mooring lines which attach the wind turbine to the seafloor, and their fatigue design is until now too much uncertain. To reduce the failure risk of these wire ropes during the service life, a research collaboration is conducted between IFPEN and LMPS of ENS Paris-Saclay which aims at replacing empirical current design methods by a multi-scale physical modeling with Finite Elements. The physical models are reducing uncertainty but imply a too large computational cost which is not compatible with its application for the fatigue life estimate of a Floating Wind Turbine mooring line. 
The thesis of F. Bussolati (Univ. Paris Saclay, 2019) developed a new robust model of the frictional contact between the wires of a metric length of the rope. The thesis of D. Zeka (Univ. Paris Saclay, 2024) developed a new model reduction method of this frictional contact problem, within the global space time solver LATIN. These works have drastically reduced the computational cost while predicting with enough accuracy the mechanical states of two wires in contact which are needed as input of a local fretting fatigue law (e.g. thesis of S. Montalvo, Ecole Centrale de Lyon, 2023). 
The current thesis will first extend at LMPS the D. Zeka approach by reformulating the LATIN solver in a kinematical framework of beam elements with small deformation, small slidings and large rotations. This development is the missing point for applying the reduced model strategy to a case of a mooring line of floating wind turbine, seeing variable traction and bending in relation to the floater motion. A demonstration on a realistic case will be conducted at IFPEN during the last year of the thesis.

Keywords: Model reduction, Domain Decomposition, geometrical non-linearity, frictional contact, floating wind turbine.

• Academic supervisor    Dr. Pierre-Alain GUIDAULT, LMPS, ORCID : 0000-0002-5647-1624
• Doctoral School    ED 579 SMEMAG, Université Paris Saclay
• IFPEN supervisor    Dr. Martin GUITON, https://www.researchgate.net/profile/Martin-Guiton
• PhD location    LMPS, Gif-sur-Yvette, France/ IFPEN, Lyon, France
• Duration and start date    3 years, starting in the fourth quarter 2024 (Novembre 4)
• Academic requirements    University Master degree in structural mechanics, mathematics in mechanics 
• Other requirements    English level B2 (CEFR), programming (python, Matlab)

To apply, send a message with title « Candidature thèse IFPEN/LMPS » with a CV, a cover letter, a recommandation and your transcripts of Master records to the supervisors below. Please check that your message is including all requested documents.