Experimental set-up of the Double Slip Joint - Investigating the settling behaviour

Abstract

The Double Slip Joint (DSJ) is a new design to connect the transition piece to the foundation pile of an oshore wind turbine. It potentially oers high dynamic strength and reliability at a lower cost thereby assisting the decrease in cost of wind energy. The design is based on a self-locking principle through vertical settlement of the joint. The objective is to investigate the settlement behaviour of the DSJ through an experi- mental set-up. Three experiments including multiple tests were conducted. Experimental results have been compared with results from a nite element model in Ansys. The self-locking behaviour of the DSJ under various loading congurations including irreg- ular environmental loading is conrmed. The DSJ settles through downward slip motions in the direction of the loading. Settlement depth increases when horizontal/vertical loads exceed previous applied loads or when their direction is changed 180 degrees. As the TP vertically settles the joint becomes stronger and more slip resistant. Slip will reduce to zero for sucient settlement. The conducted experiments led to a better understanding of the settlement behaviour and provided a benchmark data for validation of nite element models of this process. First the reader is introduced into the subject, the project denition and the approach is presented. Next, an explanation of the experimental set-up is given. Afterwards it is described how the scale model was designed and fabricated. The loading strategy is explained for three experiments. Then, the measured parameters and the data acquisition system is presented. The methods used to process the data is discussed. The most interesting results are presented in combination with a discussion and interpretation. Conclusions are made and lastly recommendations for improvement of the set-up, further testing and general development of the DSJ are given.