Global air travel continues to increase year upon year. It has been estimated that over 30,000 new passenger jetliners and freighters could be in operation worldwide by 2025. The aircraft fleet in Asia alone is expected to triple over the same period. Ensuring aircraft safety is a critical issue, so the development of advanced maintenance and repair technologies is more important than ever.

In 2007, Singapore’s Agency for Science, Technology and Research (A*STAR) launched the A*STAR Aerospace Programme to establish a common research platform that will support the growth of local aerospace companies and technology. The programme has since funded several projects, and the number of participating companies has expanded from the original four – Boeing, European Aeronautics Defence Systems, Pratt & Whitney and Rolls-Royce – to 18 over the last few years.

The programme involves teams of A*STAR researchers comprising dozens of scientists and engineers from around the world. The number of projects is on the rise, adding impetus to the search for
collaborative development with other companies and research institutes.

Robots for surface finishing

safegaurding air travel computer

© Agency for Science, Technology and Research (A*STAR

Guilin Yang leads the mechatronics team (which includes mechanical, electronic, software and systems design engineering) at the Singapore Institute of Manufacturing Technology (SIMTech). They recently completed a project on robotized finishing, which developed and customised industrial robots to smooth the edges of aero-engine components. In most aerospace factories, skilled workers handle these processes manually.

“The manual approach is a very time-consuming process because there are so many small features,” says Yang. “It is also difficult with manual operations to guarantee quality consistency, particularly in the tough working environment of these factories.”

So the team set about developing a robotic alternative. One of the biggest challenges they faced along the way was the fine control of contact force for the removal of ‘burrs’ along metal edges,
which is considered difficult to automate because edge features are usually complex.

Yang and his colleagues had to programme the robots carefully based on both the 3D model and the material removal model of the work piece, so that their paths and forces were precisely controlled. The team eventually succeeded in getting an edge profiling of components with a finishing accuracy of up to ±0.2 millimetres. Although the project is now complete, Yang says his team will continue improving the performance of the technology.

“We have excellent infrastructure, good support from the government and a strong research foundation,” he said.

Non-destructive testing


Assembly of a Boeing 767 airliner nose section © Individuo

Wei Lin, a senior scientist at SIMTech, works on developing non-destructive tests for composite materials (those made from several different materials). Ultrasonic technology is widely used for the non-destructive testing of materials such as metals, but the composite materials used in modern aircraft pose a challenge for conventional methods. Materials such as carbon-fibre-reinforced plastics have a ‘sandwich’ structure comprising laminateskins and an internal honeycomb-like arrangement, and they tend to develop very peculiar flaws.

“We want to see how these defects affect the mechanical strength of the materials. A defect may still be okay to fly, but ultimately aircraft carriers want to know when they fail,” says Lin.

Lin’s team has developed a technique that is performed at a frequency lower than that of conventional ultrasonic techniques. “This way very fine differences among flaws, including information about the defects such as depth, types and geometry, can be detected and identified,” says Lin.

Computer simulations

At A*STAR’s Institute of High Performance Computing, Tomas Karasek and his colleagues are working on two new simulation projects that could support advanced aircraft maintenance and repair perations in the future. One of the simulations aims to optimise the design of structures that are subject to high impact loads.

“Preventing damage of composite materials subject to high impact loads is still a daunting task. Our objective is to optimise composite materials, in term of the number of layers, the material’s constituents and even the orientation of individual layers, so that the test beam can survive the drop without damage,” explains Karasek.

They are also developing a faster and more costeffective method for the metal shot peening process—a cold finishing step in which small metallic balls are shot into a surface of a piece of metal to increase durability. The conventional optimisation process relies on visual inspection by an experienced technician. Karasek’s team is aiming to introduce a more objective approach by creating a tool to predict the optimal coverage given parameters such as pressure, intensity and time for components of different sizes and shapes.

“The aerospace industry is rolling out cutting-edge technology and high-tech products with high added value.” Says Karasek, adding: “However, safety and reliability is always a concern. There is a lot of room for research.”

For further information contact:

Dr Guilin Yang
Singapore Institute of Manufacturing Technology
Agency for Science, Technology and Research (A*STAR), Singapore

Dr Wei Lin
Singapore Institute of Manufacturing Technology
Agency for Science, Technology and Research (A*STAR), Singapore
Dr Tomas Karasek
Institute of High Performance Computing
Agency for Science, Technology and Research (A*STAR), Singapore