Abstract: In order to achieve the weight reduction goal of an aero-engine, the structure design of the composite bypass casing structure was carried out. According to the overall design requirements, firstly, the working environment was analyzed and the material selection was completed. Secondly, the lightweight design of the casing structure was carried out. Based on the classic laminate theory and the Cai-Hill failure criterion, the VBA calculation program for the ultimate strength of the typical laminate was developed to complete the layering scheme design of the casing. Secondary development through UG, solved the difficult problem of metal mounting seat modeling, and improved the efficiency of structural design. Through measures such as laying a thermal protective film on the inner wall of the casing and optimizing the structure of the exhaust plug of the "unloading cavity", the thermal protection design of the casing was completed. Finally, the assembly analysis and thermal deformation analysis of the casing were completed, and the external load determination of the engine working task profile was realized through MATLAB programming, and the static strength and fatigue test verification of the typical structure and the full-size casing were completed. Compared with the original titanium alloy casing, the newly designed and manufactured composite bypass casing has a weight reduction efficiency of 27.8%, reaching the goal of design. The full-scale test and the installed application of the casing further verify the reliability of the design.

Key words: aero-engine, composite material, bypass casing, structure design, verification