Study of the internal friction in synthetic fiber mooring ropes, application to splice

Offshore wind turbines are an important component of the energy transition underway in France and around the world. IFP Energies Nouvelle studies in particular the technology of floating wind turbines, which can be deployed in relative deep sea. A critical component of the floating wind turbine is the mooring line, which is often made of a chain and a synthetic fiber rope. The thesis will be devoted to synthetic fiber rope and particularly to the splice. Splicing is a very old technique, but it is, to date, the most effective solution to end a fiber rope. Despite this, rope usually breaks at the splice, whether in monotonous traction or fatigue, it is a weak point. The splice holds by friction. To understand the splice behaviour, one has to understand the friction within the rope, which is complex and poorly known. The PhD work will include :
-    Perform friction tests on ropes. These tests will be carried out on two scales: the strand scale, at ENSTA bench, and the multi-strand rope scale, on a high capacity bench at IFPEN. Specific devices will have to be designed and manufactured. The friction curves will be established, according to different configurations,
-    Develop a friction model adapted to synthetic ropes, based on the models available in the literature. Implement the model in a finite element code (Abaqus) and identify it on friction tests,
-    Characterize the contact surfaces, in particular the material changes and possible damage,
-    make splices and test them in tension, exploit the tests thanks to image analysis and simulate them by finite element, with the friction law developed in the thesis. Deduce the fragility points.
The doctoral student will use the IRDL and IFPEN test benches. He (She) will benefit from the experience of both institutes in offshore wind turbines, synthetic fiber ropes and their maritime applications. A rope provider will be involved in the thesis. The work will take place at IRDL, ENSTA Bretagne, Brest, and at IFPEN Lyon, Solaize.

Keywords: mechanics of materials and structures, multi-scale simulation, friction model, friction tests, synthetic fiber rope, floating wind turbine

• Academic supervisor    Prof. Yann MARCO, IRDL, ORCID : 0000-0002-0163-7279
• Doctoral School    ED648 SPIN, ENSTA Bretagne
• IFPEN supervisor    Dr Michaël MARTINEZ
• PhD location    IFPEN, Lyon, France and IRDL / ENSTA Bretagne, Brest, France  
• Duration and start date    3 years, 3 years, starting in the fourth quarter 2024 (November 4)
• Employer    IFPEN
• Academic requirements    University Master degree in Mechanical Engineering or in Mechanics of Materials
• Language requirements    English level B2 (CECR)    
• Other requirements    Programing, finite element simulation

To apply, please send your cover letter and CV to the IFPEN supervisor indicated below.