Design Optimization of Rolled Double Slip Joint Based on Scale Experiments and FEM

Design Optimization of Rolled Double Slip Joint Based on Scale Experiments and FEM

Xiao, Y.

Metrikine, A.V. (mentor)

Mechanical, Maritime and Materials Engineering

Offshore and Dredging Engineering

2016-10-17

The Double Slip Joint (DSJ) is a new design concept to connect the transition piece to the foundation pile of an offshore wind turbine. It potentially offers high dynamic strength and reliability at a lower cost of installation and maintenance compared to other conventional techniques thereby contributing to the decrease of the cost of the wind energy. The design is based on a self-locking principle through vertical settlement of the joint. The objective of the thesis is the further development of a DSJ which is optimized for fabrication, whereby the rings are produced by rolling. First, the geometry of the Rolled DSJ scale model is designed. Second, a rolled-DSJ scale model with a larger wedge angle and ring thickness has been built and five experiments including multiple tests were conducted. Third, the rolled-DSJ is excited by a high frequency load and modelled in ANSYS in order to investigate the dynamic behaviour under settlement. The Rolled DSJ has the same settling behaviour and principle with machined DSJ. The self-locking principle of both types of DSJ (machined and rolled DSJ) under various loading conditions is confirmed experimentally. Settlement depth increases when horizontal/vertical loads exceed previously applied loads or when the direction of the applied load is switched. Installation of DSJ underwater seems not to influence the settling behaviour. An extreme settling depth could be reached when the vertical load is against only by the normal force from the ring. Compared with low frequency excitation, higher frequency excitation yields shorter installation periods at lower amplitude. However, in reality, large amplitude loads required for settling have frequency below 0.5 Hz, the settlement of DSJ per cycle should be similar to quasi-static behaviour. First the reader is introduced into the subject, the project definition and the approach is presented. Afterwards it is described how the scale model was designed and fabricated. The loading strategy is explained for five experiments and the results and interpretation are presented. Then, a FE model of the prototype is developed in ANSYS and a parametric study is performed. Conclusions are reached and recommendations for further testing, numerical analysis and development of the DSJ are given.

http://resolver.tudelft.nl/uuid:c8e70dac-be37-4012-8c89-2348e3c22eec

2021-10-17

Student theses

master thesis

(c) 2016 Xiao, Y.