Tolerance Design of Multistage Aero-Engine Casing Assembly by Vibration Characteristic Evaluation

A multistage aero-engine casing is a typical thin-walled structural component that is required to maintain a stable dynamic performance because it is a key component for transmitting thrust from an engine to a plane. However, the manufacturing and assembly processes will generate initial assembly deviation, influencing the mechanical properties of the casing during service. Previous tolerance design had few considerations of the effect of assembly deviation on the dynamic characteristic stability. In this paper, a novel performance-oriented tolerance design method for multistage aero-engine casing is proposed. Based on the shell theory, an analytical model is constructed to present the bolted jointed multistage casing assembly. By varying the assembly variables, the mapping relationship between the manufacturing precision and the indeterminacy of dynamic characteristic is established. Through the mapping relationship, an acceptable assembly tolerance with a specified stability requirement is obtained and adopted into the finite element model to show the effectiveness of the actual assembly structure. The presented method provides a significant reference for tolerance design in the actual assembly of the multistage casing.