Thermomechanical design and analysis of ceramic composite exhaust diffuser unit

The exhaust diffuser unit of a modern ail breathing engine has been chosen for a design study using ceramic composites as part of a wider research programme to introduce new materials into aeroengines. Although the unit is relatively, lightly stressed, it is subject to a severe thermal environment, and poses a significant lest of the behaviour of new materials. Material selection has been based on deformation maps, using merit parameters for strength and toughness under thermal shock. Heat transfer analysis of the conceptual design has established the thermal transients, and allowed the estimation of thermally induced stresses. The stress levels are sufficient to induce microcracking in ceramic composites, and have required the development of a simple damage mechanics model. (C) 1995 The Institute of Materials.