Feasibility investigation of non-metallic and light weight metallic materials for light weight compressor pistons

Steel and aluminium have been the traditional materials of choice for pistons. In order to reduce moving mass-related vibrational problems, a feasibility assessment is made of the application of other materials in a project for the research group of the EFRC. In particular, polymer and metal matrix composite as well as polymers as such were evaluated for this fatigue driven application. Since specifi c materials ideally require tailored designs, preliminary designs were conceived for all materials on the shortlist. The work carried out up to now reports on progress made with the feasibility assessment of one particular mass saving application of solid polymer design for a piston. We applied a combined theoretical and experimental approach to assess applicability and do fi nal material selection among the many possibilities. It was anticipated that very high cycle fatigue behaviour prediction at elevated temperature would be the most important aspect. As manufacturing quality is important, scaled demonstrator manufacturing trials are undertaken as well. Fatigue behaviour of several polymer candidates such as high temperature grades epoxy (thermoset) and polysulfones (thermoplastic) was analysed in the light of more extensive characterisation of mechanical properties at different strain rates and creep and crack propagation behaviour. Such an analysis was explored to enable fatigue prediction at a scale which is normally beyond practical or financial restraints. The difficulties as well as a road ahead of this work in support of a dramatic mass reduction of compressor pistons will be highlighted.