Diamond Light Source facility aids engine development

The Diamond Light Source, the UK’s national synchrotron science facility, revealed today that Rolls-Royce’s latest Trent 1000 turbofan engines were developed using its new high-energy engineering beamline.

The engine maker was the first to use Diamond’s newest research facility, which was officially opened today. The new facility is capable of creating molecular-scale 3D images of large objects such as aerospace and engineering components and exploring their structure in atomic-scale detail.

Rolls-Royce’s new engine powers the Boeing 787 Dreamliner, which first flew in December 2009 and is due to enter service in 2011. The engine maker used Diamond’s research station, an addition to the Joint Engineering, Environmental and Processing (JEEP) beamline, to assess the effectiveness of local surface treatments.

Diamond’s X-rays were used to look at the atomic detail of a large-scale component – a complete engine fan blade measuring approximately 1m in length. The JEEP beamline is the only place in the UK where the internal stresses and strains of components up to two tonnes in weight and beyond 1m in length can be studied with such precision.

Prof David Rugg, material specialist at Rolls-Royce, explained the benefits of the JEEP beamline: ‘The use of advanced materials in safety critical applications requires a high level of understanding and good predictive capability. To this end, improved material characterisation with respect to the evolution of microstructure, crystallographic texture and residual stress is planned by Rolls-Royce. This will be conducted mainly via research programmes with leading academics using the JEEP beamline.

‘Development of new process routes and optimisation of existing processes will improve material properties and reduce cost. JEEP allows detailed, in-situ examination of deformation mechanisms within advanced engineering materials. Information derived in this way will significantly improve the understanding required to develop physically based models – these will be key in improving durability of engineering components.’

The first use of the new research station on the JEEP beamline was to look at a fan blade from a Trent 1000 engine. Specifically, Rolls-Royce was interested in the effectiveness of its surface treatment to the base of the fan blades on some of its Trent engines to provide additional integrity margins.

The treatment works by imparting a compressive stress into the surface of the fan blade root, effectively reducing potential for the initiation and propagation of cracks.

Dr John Schofield, a Rolls-Royce engineer and lead researcher on the project, explains: ‘We need to quantify the depth and magnitude of the compressive stresses induced by the treatment to understand how effective it is. We routinely measure residual stresses in components and the JEEP beamline provides us with an alternative way to do this. We were very impressed with its new capabilities. It enabled us to look effectively inside the fan blade and measure through-wall residual stresses in a non-destructive manner. If we had done this experiment in the laboratory we would have had to machine metal away prior to taking the measurements and then correct for the metal removal. Not only is the laboratory approach destructive but it is also more time consuming and less accurate.’

The team of researchers from Rolls-Royce and Diamond used energy dispersive X-ray diffraction to examine the stresses within the fan blade. They focused a beam of multi-wavelength X-rays onto the contact area of the fan blade root. The X-ray beam is diffracted by the sample, producing a spectrum with characteristic intensity peaks at specific photon energies. The position of these peaks provides information about the structure of the sample. Shifts in peak position are used to measure internal strains, enabling the researchers to measure the extent of the compressive strain.

Principal beamline scientist on JEEP Dr Michael Drakopoulos said that when fully operational, JEEP will be able to accommodate a broad range of high-energy X-ray experiments, delivering a wide variety of techniques; from imaging and tomography, to X-ray diffraction and small-angle X-ray scattering.

A team from Imperial College London headed by Prof Peter Lee is also using JEEP to examine the internal microstructure on a range of materials including metal alloys, frozen soils and bone tissue with levels of precision that have never previously been possible. Other users include the University of Manchester and high-tech manufacturer Johnson Matthey, which uses Diamond to develop products such as bio-engineered pharmaceuticals, energy-efficient catalysts and nano-electronic components.

The JEEP beamline at Diamond first went into operation in November 2009 when scientists from the University of Oxford used the first research station, EH1, for materials deformation analysis.

The new facility, EH2, extends JEEP’s capabilities, providing scientists and engineers with a space for large-scale engineering and processing experiments such as in-situ measurements; simulating the service conditions experienced by real engineering components while their internal stress state and structures are continually monitored by the X-ray beam.

JEEP is part of the second phase of construction at Diamond, which is due to be complete in 2012. Funding for Phase III, the design and construction of a further 10 beamlines, was announced by the government in October this year and will bring the total number of experimental stations to 32 when complete in 2017.