Performing fatigue crack growth tests in air and in seawater using a new neutron imaging facility – IMAT (Imaging and Materials Science & Engineering) – to measure the residual stresses in offshore monopile weldments. Testing is taking place both on Cranfield campus and the ISIS research facility at Rutherford Appleton Laboratory.

At a glance

  • DatesAugust 2013 – February 2018
  • SponsorScience and Technology Facilities Council (STFC)
  • Fundedn/a
  • PartnersISIS; a centre for research at the Rutherford Appleton Laboratory (a STFC facility), UK

Offshore wind turbine foundations need to be structurally optimised. This four-year project is assessing the influence of residual stresses on fatigue, fracture mechanics and structural integrity of offshore wind turbine structures.

An assessment of how residual stresses interact under variable fatigue loading amplitudes, both in air and in a seawater environment (without cathodic protection), is being carried out; consequently, near-threshold crack propagation behaviour of wind turbine structures will be examined.

This is focused mainly on welded components and will provide an understanding of residual stress levels and their redistribution behaviour in large-scale welded components. Neutron diffraction measurements and numerical finite element techniques are being employed to reduce the effect of damaging residual stresses in offshore wind monopile structures.

Anaïs Jacob, an EngD (Engineering Doctorate) student in the Renewable Energy Marine Structures Centre for Doctoral Training (REMS CDT), is working with Cranfield academics on this research.

Further information

For more information, visit