Session: 03-02-01 Fatigue Performance and Testing

Submission Number: 180391

Improved Fatigue Capacity of Tubular Joints Welded by Robots 

Fatigue is the dominant design factor for offshore wind foundations, which represent a significant part of the wind farm CAPEX. Foundations made of tubulars are robust structures, but their manual fabrication is very labour intensive. Robot welding could increase their fabrication speed and decrease the variability in weld quality, but the technology is still in its early market introduction stage.

The JACO (Improved Fatigue Life of Jacket-type Connections) Joint Industry Project was established to compare the fatigue strength of joints produced by robots compared to joints that were welded manually. The joints had representative dimensions for tubular joints for offshore wind energy generators, with chords of diameter 1260mm and thickness 50mm, while the braces had a diameter of 610mm and a thickness of 25mm. The same geometry was produced by the different fabricators in order to compare the performance of each specific manufacturing.Each joints was then tested in fatigue either on a classical frame with hydraulic actuators, or on a recent system applying the load in resonance. In the last case the testing frequency could be as high as 20Hz.  The results found that the resonance testing provided similar testing results as the the classicalone. The fatigue strength of the joints that were manually welded was very close to the mean T-curve. For the robot welded nodes, it was found that some manufacturers had consistent better results than the mean T-curve, while some others were more close to the T-curve.

Presenting Author: Philippe Thibaux OCAS

Presenting Author Biography: Philippe Thibaux graduated from the University of Brussels in 1997 and obtained a PhD in Material Sciences and Engineering from the Ecole des Mines de Paris in 2001. He joined the company OCAS where he has been in charge of different research projects and programs related to physical metallurgy and structural integrity. In his most recent role, he is supervising different projects related to structural integrity and the advanced testing methodologies at OCAS, particularly in the field of fatigue.

Authors:

Philippe Thibaux OCAS
Jeroen Van Wittenberghe OCAS