Topology Optimization of Large Scale Turbine Engine Bracket Assembly with Additive Manufacturing Considerations

Abstract

The objective of this paper is to perform topology optimization of an assembly structure considering additive manufacturing and the associated expanded design spaces. The examined assembly is an existing turbine engine design, comprised of 44 components, which has undergone rigorous real world testing and verification.

Two different topology optimization approaches were considered, using four distinct load cases, considering various mechanical forces and anticipated inertial loads, meant to replicate the most extreme load cases experienced in takeoff, landing, and operation at altitude. The first optimization considers cut-out topology optimization, in which the sheet metal profile of the original bracket assembly design is maintained, while the size and arrangement of cut-outs is optimized. The second optimization features an expanded design space, meant to be representative of the improved design flexibility afforded by recent advances in metal additive manufacturing technology.

When the design space limited to conventional sheet metal arrangements was considered, a total weight savings of approximately 25% was obtained, while maintaining equivalent maximum displacement and compliance values. In comparison, the increased geometric flexibility associated with the additive manufacturing design space allowed for a weight reduction of 66%, while reducing maximum displacement within the assembly by approximately 50% in each load case.

The expanded design space and the associated drastic volume reduction from the initial design vector present several complications. An incremental design space reduction and refinement is presented. All designs are re-interpreted for manufacturing, with manufacturable designs verified through finite element analysis for comparison with original design. A variety of recommended modelling considerations are presented.