Turbine blade fir-tree root design optimisation using intelligent CAD and finite element analysis

This paper is concerned with automation and optimisation of the design of a turbine blade fir-tree root by incorporating a knowledge based intelligent computer-aided design system (ICAD®) and finite element analysis. Various optimisation algorithms have been applied in an effort to optimise the shape against a large number of geometric and mechanical constraints drawn from industrial experience in the development of such a structure. Attention is devoted to examining the effects of critical geometric features on the stress distribution at the interface between the blade and disk using a feature-based geometry modelling tool and the optimisation techniques. Various aspects of this problem are presented: (1) geometry representation using ICAD® and transfer of the geometry to a finite element analysis code, (2) application of boundary conditions/loads and retrieval of analysis results, (3) exploration of various optimisation methods and strategies including gradient-based and modern stochastic methods. A product model from Rolls-Royce is used as a base design in the optimisation.