Multidisciplinary Integration and Robustness Evaluation Applied to Low Pressure Turbine Casing Design

In modern aerospace engineering design context one of the most important task is managing and simulate properly the effect of uncertainties on the response and performance of the system. In fact real engineering problems are characterised by random variations of material property, variation of loading conditions, manufacturing tolerances, etc. Different approaches have been developed by the research community to address uncertainties; while reliability methods primarily deal with probability of constraint satisfaction or violation, robust design methods have focused on the variation of system responses due to design parameters random variation. In this paper a robust design (RD) analysis of gas-turbine casing is performed in order to estimate how much uncertainties affect the life of the component. The RD analysis is performed in a multidisciplinary environment since the casing is subjected to thermo-mechanical loads. First thermal steady-state analysis has been performed changing randomly the boundary conditions (heat transfer coefficient and air temperature) and the temperature distribution on the casing is calculated. Then the structural analysis is performed changing geometrical dimensions on the base of defined tolerances and process capability. The result of the Monte Carlo analysis is a statistic distribution of the stress in the critical locations. This information is used to estimate the statistic distribution of the life in each critical location. The obtained result consents to evaluate the risk that some critical location exceeds the life margin limit.