The Open University’s Stress Mapping expertise is helping worldwide industry design against failure

The Open University’s Stress Mapping expertise is helping worldwide industry design against failure

Open-Uni-SoR-IntroThe life and safety of engineered structures for aerospace and power generation applications can be compromised, or enhanced, by (hidden) residual stresses developed during manufacture and service.

A deep understanding of material and structural behaviour can be delivered by mapping internal stresses, creating opportunities to optimise assessment methods, design for light-weighting, validate analytical models, and extend the life of components and structures.

Mapping residual stresses

The Open University’s Materials Engineering Group has developed powerful software (SScanSS) for mapping residual stresses in complex structures using neutron diffraction, a non-destructive stress measurement technique. In parallel, the group has established StressMap, an international business unit providing a state-of-the-art residual stress measurement service using the Contour method (based on world-leading Open University research). StressMap applies this technique to map residual stresses acting in multiple directions throughout complex components by undertaking serial contour cuts or by combining it with other measurement techniques.

The group’s work has had international impact across several industrial sectors. Its SScanSS neutron diffraction instrument software for simulating and controlling residual stress experiments is now adopted at eight facilities worldwide and has benefitted numerous multi-national companies, for example, General Motors, John Deere, Airbus, Tata Steel, and Pacific Rail Engineering.

Reinforcing aircraft wings

The Open University’s expertise and research has influenced aerospace structural designs through development and application of hybrid residual stress characterisation techniques. Contour measurement technology is being used by the US Air Force, which now has the capability to perform measurements in-house and support work with both NASA and the US Navy.

Technology Product Leader, Airbus Operations Limited, said: “Research in two key areas has resulted in an improved understanding of the mechanisms by which adhesively bonded selective reinforcement may be exploited [...] Aided by The Open University’s contributions, Airbus has achieved TRL3 [Technology Readiness Level 3] for bonded crack retarders applied to wing structures. This represents a sizable investment to date, and has firmly established selective reinforcement as a candidate for aircraft wings.”

Extending the life of power stations

In the electricity industry, stress mapping research at The Open University has been applied to optimise and validate computational weld mechanics models for nuclear power plant operating in the UK, Japan and Canada, and for future reactor designs. Moreover this research has contributed directly to lifetime extension safety cases (from 2011 to 2019) for Hartlepool and Heysham I nuclear power stations.

The Head of Research and Development, EDF Energy said: “We have a fifteen-year long relationship with The Open University and consider its expertise in combining small scale and large scale residual stress measurement techniques, together with analytical modelling techniques, to be unique.”

The Open University gratefully acknowledges funding for this research from EPSRC, the East Midlands Development Agency, Rolls-Royce, EDF Energy, Airbus, Lloyds Register Foundation, JNES and numerous awards of neutron.

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