Tue, 28 April, 2020
TWI held a successful webinar about ‘Structural Integrity and Fatigue in Offshore Wind’ on 16 April. The event, which was hosted by Principal Project Leader Carol Johnston attracted 440 registrants and around 215 attendees at its peak.
Following a brief introduction to TWI, Carol set the scene for the structural integrity challenges faced for the offshore wind sector, before detailing the specific aspects that affect the integrity of welded joints. This was followed by a snapshot of the research programmes currently underway at TWI before the webinar closed with a question and answer session.
During the informative event, Carol noted how wind turbines face particular challenges due to the size of the structures and the limited access that is available to them for inspection and maintenance. In addition, due to the fast pace of the industry, there has been knowledge transfer from other industries, for example, oil and gas, and a drive for low cost fabrication methods to meet the unexpected challenges associated with new designs.
Looking into the structural integrity of joints in the offshore wind sector, Carol noted that bolted joints are critical for integrity as well as speaking on the difficulties associated with fatigue cracking. The webinar also detailed how arc welding can result in slag inclusion, a potential fatigue crack source, at the weld toes. In addition, the webinar touched upon residual stress, misalignment, and fatigue classes in welds, while also looking at methods for weld improvement.
Of course, like other industries, offshore wind is governed by codes and standards covering the structural integrity of joints, including BS7608 (‘Guide to Fatigue Design and Assessment of Steel Products’) and BS7910 (‘Guide to Methods for Assessing the Acceptability of Flaws in Metal Structures’).
The snapshot of research at TWI gave details of two PhD projects underway at the National Structural Integrity Research Centre (NSIRC) and a new core research programme project investigating ‘Transition Behaviour of Corrosion Pit to Fatigue Crack.’ Carol also spoke on TWI research on the fatigue strength of large bolts and the fatigue behaviour of mooring chain, that could potentially be used in floating wind turbine structures.
Carol’s presentation led to a lively question and answer session where she was able to provide answers to a range of queries, including whether the internal structure of wind turbines also suffer fatigue related problems. There were also questions related to materials, the use of polymeric composites, critical joint location on offshore structures, NDT, crack initiation, underwater welding, corrosion protection, industrial demand, and more.
The webinar is another example of how TWI is working to continue in our support for industry during the current lockdown.
Those that missed the live webinar can see a YouTube recording here.