Materials selection process for gas turbine engines for modern aircrafts

The stage of progress in today’s gas turbine engine is possible not only due to advancements in design, aerodynamics and thermodynamics, but also because of improvements in materials, manufacturing and surface technology. The thermal efficiency of a gas turbine engine is closely related to the temperature that the system is able to operate in. An engine capable of operating at a higher temperature is more efficient than one that operates at a lower temperature [1], [2], [3]. Therefore, in the design of aircraft gas turbine engines, advancements in technology to seek higher operating temperature have always been of considerable attention. Consequently, the operating temperature of gas turbine engine has risen considerably over the decades. Not surprisingly, the requirements of materials for gas turbine engine components have also become more demanding. Beside higher temperature, there are various other combinations of stresses (such as fatigue and corrosion) that also require consideration. These have forced manufacturers to seek improvements in traditional materials or to invent new ones. This dissertation aims to achieve two objectives. The first is to explore a material selection technique that is applicable for gas turbine engine at the preliminary stage of the design process. Currently, there are several materials selection methodologies, but most of them require expert knowledge of the problem to assign weight factors. Michael Ashby material selection methodology [4] was extended to address this area for commercial aircraft gas turbine engines. Cambridge Engineering Selector (CES) software [5] was used to facilitate the methodology. The demanding constraints in each of the gas turbine engine main components were critically examined. Informative case studies were used to demonstrate the concept of application. The second objective is to review old and existing materials that were/are used as gas turbine engine materials. Investigation focused in the reasoning behind the use and the cause of introducing replacement or alternative materials. In addition, there are discussion and proposal of potential new materials that show promise of use in future gas turbine engines.Master of Science (Aerospace Engineering