Manchester Uni helps Rolls-Royce to improve engine performance

According to the University of Manchester, fan blades in aircraft engines endure large loads and high-frequency vibrations. Over time, these stresses can create microscopic cracks in the blades which can lead to issues in service.

Reportedly, the traditional method for stopping cracks is ‘shot-peening’, ie firing shot (round metallic, glass or ceramic particles) at the blades in order to rework the metal’s surface. The shallow indentations create compressive residual stresses that stop cracks growing.

The University of Manchester has reported that Rolls-Royce wanted to explore alternative cutting-edge methods with leading experts at Manchester.

The academic task force therefore investigated laser shock peening (LSP), which introduces compressive stresses to a much greater depth via plasma created by a powerful pulsed laser.

Manchester solution: stress management for stronger materials

Manchester researchers worked with Rolls-Royce to study the fundamental nature of LSP-induced compressive residual stress. LSP has demonstrated it is an improvement on more established shallow peening: it effectively compresses the atomic structure of the fan blades to make them much more resilient to cracking and fatigue.

Professor Philip Withers, Regius Professor of Materials, received the Armourers and Brasiers’ Company Prize from The Royal Society in 2010 in recognition of his use of neutron and hard X-ray beams to map stresses and image defects.

He said: “Our team analysed the potential of LSP to improve fan blades’ fatigue resistance by using penetrating synchrotron X-ray beams.

“We discovered that this method generates deep compressive stresses which remain stable during air travel. This testing confirmed LSP could be safely applied to the fan blades to make them stronger and last longer.

“We’ve got excellent facilities and expertise at the Materials Performance Centre, Engineering and Process Metallurgy Group, and Materials Testing and Analysis Unit.

“The combination of academic leadership, relevant research expertise and our ability to work closely with industrial partners makes Manchester stand out in this field.

“Rolls-Royce trusted our evidence and immediately adopted LSP to treat its Trent 800 engines.”