Lightweight design methodology for marine rotating machinery: Co-design of equivalent material parameters and structural performance in lattice-architected impellers

Abstract

This study presents a material-structure co-design framework for lightweight lattice-architected impellers targeting marine propulsion applications. By replacing explicit micro-scale lattice modeling with equivalent material parameters (density, elastic modulus, Poisson’s ratio), a parametric finite element framework integrated with global sensitivity analysis and multi-objective optimization is developed. Global sensitivity analysis quantifies the overwhelming contribution (>80%) of inertial loads (rotational speed and density) to structural responses, providing a quantitative justification for lightweight design. By subsequently excluding the dominant speed variable, multi-objective optimization yields a distinct Pareto frontier between impeller mass and structural integrity, where equivalent stress ranges from 8.4 × 10⁷ to 8.6 × 10⁷ Pa, demonstrating how tailored lattice properties can achieve optimal weight-performance trade-offs. Three key contributions are made: (i) first application of equivalent material parameters (ρ/E/ν) to the multiscale co-design of high-speed marine lattice impellers; (ii) quantitative separation of inertial load versus material effects via global sensitivity analysis, showing that rotational speed contributes >99% to deformation and ∼80% to stress, providing rigorous data support for lightweight prioritization; and (iii) an engineering-ready Pareto frontier between impeller mass and structural integrity (equivalent stress ranging from 8.4 × 10⁷ to 8.6 × 10⁷ Pa), filling the gap in lattice design for rotating machinery. The proposed methodology provides a systematic design tool for developing lightweight rotating components, with demonstrated applicability to marine propulsion systems (e.g., compressor impellers in ship gas turbines) and potential extension to propellers, pumps, and other ocean engineering structures.