Global sensitivity analysis of turbine rear casing based on failure probability

Abstract

The aero-engine turbine rear casing is a key component for aero-engine safety，but it has complex working conditions and multiple uncertain factors. In order to explore the influence of the uncertainty of input random variables on the failure probability of a turbine rear casing structure，a parametric finite element model is established for the deterministic analysis of the aero-engine intermediate casing. Considering the uncertainty of material properties，geometric parameters and external loads of the aero-engine intermediate casing，the limit state functions are constructed for the two most typical failure modes：static strength and stiffness failures. By constructing an adaptive Kriging surrogate model and combining importance sampling method，the failure probability of the casing structure is predicted. The uncertainty source of the reliability of the turbine rear casing structure is analyzed by a global sensitivity analysis method based on failure probability. The importance order of all input random variables is identified， and a global sensitivity analysis framework for aero-engine turbine rear casing is proposed. The results show that， under the two failure modes and system failure modes，the engine thrust and linear expansion coefficient have the most significant influence on the structural failure probability，which should be considered emphatically. The length of inner and outer casing and the elastic modulus of the material have little influence on the structural failure probability of the turbine rear casing，which could be ignored.

Keywords

• turbine rear casing
• global sensitivity analysis
• adaptive kriging
• importance sampling
• markov chain