Details of Grant 

EPSRC Reference:	EP/C545826/1
Title:	A Novel Framework For Predicting, Measuring and Analysing Weld Induced Residual Stresses
Principal Investigator:	Truman, Professor CE
Other Investigators:
Researcher Co-Investigators:
Project Partners:	Airbus Group Limited Babcock International Group Plc (UK) British Energy Doosan Power Systems (Mitsui Babcock)
Department:	Mechanical Engineering
Organisation:	University of Bristol
Scheme:	Standard Research (Pre-FEC)
Starts:	10 October 2005	Ends:	09 April 2009	Value (£):	424,764
EPSRC Research Topic Classifications:	Materials testing & eng.
EPSRC Industrial Sector Classifications:	Aerospace, Defence and Marine Energy
Related Grants:
Panel History:	Panel Date Panel Name Outcome 13 Apr 2005 Engineering Fellowships Interview Panel 2005 Deferred
Summary on Grant Application Form
The project will provide a methodology for determining residual stresses in welded engineering components without the need for costly numerical modelling. It will also develop accurate measurement techniques to validate these predictions. Residual stresses are self-equilibrating stresses existing in components under uniform temperature conditions and no applied loads. In industrial applications, the principal joining process between metallic components is welding. Welding introduces highly tensile residual stresses near the weld due to molten metal cooling and contracting. This pulls the surrounding material away from its equilibrium position and generates a residual stress field. It is absolutely vital that a knowledge of the magnitude and spatial distribution of these residual stress fields exists as they can combine with applied loads and promote failure of a component or structure at loads the designer would view as safe . Unfortunately, with so many variable and unknown parameters in processes such as welding, it is extremely difficult to quantify their magnitude and spatial distribution.By adopting an analytical approach, i.e. one where for a given set of input parameters an equation predicts the component response, to residual stress modelling, it is possible to systematically study the effect of different input parameters in a way which is not possible with numerical, or Finite Element models. This provides a means to understand differences in the residual stress fields as different sized specimens are studied. This is important as experiments are usually made on laboratory sized specimens and the results scaled to full size industrial applications. This is known to be invalid in many circumstances.Likewise, by utilising an analytical approach, the results of residual stress measurements, which determine the strain or distortion of a component, may be interpreted in such a way as to provide more information about the pre-existing residual stress field. Although possible, in theory, to interpret these results using Finite Element models, it is simply not practical to re-analyse each individual measurement. The provision of an analytical solution will enable measurement specific calculations to be made.The final task of the project will apply the same technique to study the influence of residual stress fields on the subsequent fracture behaviour of components. The motivation is the same as previously, i.e. it is simply not practical at present to re-model each individual problem as part of a Finite Element model. The three tasks will provide an unparalleled and unified approach to weld residual stress modelling and measurement and its implications for structural integrity assessments.
Key Findings
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Potential use in non-academic contexts
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Organisation Website:	http://www.bris.ac.uk