Recent Advances in the Fatigue Analysis of Welded Structures

Processes for the fatigue analysis of metallic structures are now well defined, both in the stress-life or strain-life regimes.   It has been recognized for some considerable time that the design of fabricated welded structures can be heavily dependant on the fatigue life of welded regions.  The optimization of such designs is therefore dependant on having good predictions of the fatigue life at the weld.

The fatigue life of welded metallic structures is dependant on the increased levels of stress found at the weld toe, root or throat due to weld geometry and the reduction in material properties with the heat affected zone.  In addition to this, the amount of fusion of the weld into the parent metal and whether there is hot or cold fusion at a weld end all add to the inherent variability of welded structures.  In short, the prediction of a robust fatigue life at a weld is extremely difficult.

Over the past few years there have been many efforts to improve the fatigue prediction of welds through FEA and other methods and also to address the inherent variability in fatigue life. The areas addressed have been:-

• The FEA modeling of the weld.
• Sampling of the appropriate stress tensors at various locations around the weld.
• Improved algorithms within the fatigue life prediction software.
• Improved material models.

This seminar provided practicing FEA analyst with an overview of the work being carried out in the area of weld fatigue.  It included industrial case studies in real world applications of current weld life prediction and modeling methods which gave an insight into the decisions to be taken to achieve robust results.

Information was also provided on the background and basic principles of weld life prediction which covered the fundamentals of welded joints, together with the underlying theory. There was also presentations given by vendors of fatigue life prediction software which covered the details of the techniques that have recently been, or are about to be, implemented. 

Presentations 

Chairman’s Welcome & Introduction
David Boon, Jaguar Land Rover

Aspects of FE-Based Fatigue Life Prediction in Welded Sheet Structures
Peter Heyes, NCode

FEA for Assessment of Weld Fatigue in BS7608
Simon Smith, TWI

Fatigue Analysis from FEA Method for Evaluation of Welded Structures
Pawel Sobczak, Safe Technology

Some Observations on Hot-Spot Stress Techniques
Jim Wood, University of Strathclyde

Recent Developments in Finite Element Simulations of the Welding Process
Adib Becker, University of Nottingham

Durability Assessment and Optimisation of Welded High-Strength Steel Vehicle Structures
Yi Gao, Corus Group

Predicting Weldment Fatigue In Structural Nuclear Supports
Matthew Massingham, Rolls Royce Marine Power  

Fatigue Characterisation of Joint Specimens in Automotive Industry
Zongjin Lu, Jaguar Land Rover