Simultaneous isotropic and anisotropic multi-material topology optimization for conceptual-level design of aerospace components

The aerospace industry is constantly looking to integrate advanced materials and manufacturing methods into their airframes to achieve new breakthroughs in lightweight design. Enabling these advancements are new computational methods such as multi-material topology optimization. While this field has expanded in recent years, the current state-of-the-art typically focuses on academic-level examples and is usually restricted to isotropic-only or anisotropic-only studies. To address this gap, this paper presents practical examples of multi-material topology optimization for the aerospace industry, including the first application of both isotropic and orthotropic material models simultaneously in the same 3D design space. Here, the structural legs and seatback for a passenger aircraft seat are considered at the conceptual level and focuses on the use of single- and multi-material designs to determine the optimum utilization of a new aerospace-grade composite alongside aluminum and magnesium. Designs are discussed and compared with preliminary considerations on performance and cost, with the inclusion of various alternative manufacturing-based constraints. Ultimately, this paper seeks to demonstrate the practical capability of multi-material topology optimization, and review methods and perspectives for evaluating various single- and multi-material design combinations.