European Commission

Program No:



Centro Sviluppo Materiali SpA, Italy
ISQ, Portugal
SZMF, Germany
University of Thessaly


Recently the technological evolution in structural steels, particularly in the area of offshore and marine applications, seems to point to a trend towards an increasing use of high strength weldable steels. Accordingly, the need to develop specific knowledge about the fatigue behaviour of high grade steel welded joints is becoming a more crucial issue. In parallel with these developments a consistent improvement, both in the mechanical properties of consumables and in welding technologies, has been achieved in order to guarantee high-quality/high-strength steel welded joints for lightweight structures.
In this context was born the FATHOMS project aimed at an improvement in knowledge on the fatigue behaviour of welded joints in high strength steels (specified minimum yield strength ? 420 MPa), contributing to improve design criteria for welded structures and components for offshore applications, in terms of reductions both in weight and cost. The final goal of the proposed project is to produce and collect valuable information to extend the applicability of design standards to the use of high strength steels in welded structures.
In particular in order to achieve the above mentioned goal the work will be mainly focused on the evaluation of:

  • the eventual conservativeness of both the selected design S-N curves and the fatigue damage tolerances recommended in the Standards when high steel grades are used;
  • the influence of loading conditions similar to those encountered in service (e.g. high R or ?mean values and selected load spectra), together with various external environments (such as cathodic protection in sea water), in conjunction with the use of new welding technologies and post-weld treatments.


U.Th. Principal Investigators:

Philip Perdikaris


Spyros Karamanos, Gregory Haidemenopoulos


1,334,155 Euros

UTh Budget:

190,000 Euros


36 months (July 2005 - June 2008)


Figure B1 1

Figure 1: S-lay barge.

Figure B7 2
Figure 2: Welding in offshore pipelaying vessel.

Figure B7 3
Figure B3: Marcoscopic view of high-strength steel welded plated T-joint.

Figure B7 4
Figure 4: CTOD testing of high-strength steel specimen.

Figure B7 5
Figure 5: Four-point fatigue (cyclic) bending of high-strength steel welded plated T-joint.

Figure B7 6
Figure 6: Fatigue crack high-strength steel welded plated T-joint.

Figure B7 7
Figure 7: Fatigue crack high-strength steel welded plated T-joint.

Figure B7 8
Figure 8: Fatigue crack high-strength steel welded plated T-joint.

Figure B7 9
Figure 9: Finite element simulation for determining stress concentrations.

Spyros A. Karamanos, PhD

Department of Mechanical Engineering | University of Thessaly | Pedion Areos, Volos 38334, Greece
Phone: +30 - 24210 74086, 74360 | Fax : +30 - 24210 74360 | Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

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