Digital Twin–Driven Design of Functionally Graded Additive Manufactured Structures for Deep Space Missions: A Review and Framework Perspective

Abstract

Deep space and cislunar missions, including those associated with Artemis II mission, expose spacecraft structures to sustained thermal gradients and radiation environments that differ significantly from low Earth orbit conditions. Addressing these challenges requires material and design strategies capable of managing heat transfer while maintaining structural efficiency under strict mass constraints. Digital Twin methodologies, functionally graded materials (FGMs), and additive manufacturing (AM) have each been explored in the aerospace domain; however, their integrated application at the material–structure design level remains relatively underdeveloped. This work examines the combined potential of these approaches through a consolidated review perspective and introduces a physics-based framework for evaluating graded structures under representative deep space conditions. In this design-stage interpretation, the Digital Twin is treated as a high-fidelity virtual prototype rather than a sensor-coupled operational system, enabling systematic pre-fabrication exploration of material grading strategies. The framework incorporates a one-dimensional steady-state heat conduction model with spatially varying thermal conductivity, coupled with a simplified radiation attenuation formulation based on the Beer–Lambert relation. Material grading is described using a power-law distribution, allowing systematic assessment of how thermal resistance can be redistributed across the structure. Parametric analysis shows that increasing the grading exponent significantly alters internal temperature profiles and can reduce heat flux by up to approximately 69% compared to a homogeneous configuration, without modifying boundary conditions. Within the simplified modelling assumptions, radiation attenuation is primarily governed by material thickness; however, in realistic deep space environments, attenuation is expected to depend on material composition, indicating potential coupling between thermal and shielding performance. Overall, the study provides a structured and physically interpretable pathway for extending Digital Twin–based evaluation to material-level design, offering a computationally efficient approach for the early-stage assessment and optimization of functionally graded structures for deep space applications.