Structural Design Strategies for Energy-Absorbing Auxetic Metamaterials: A Review

Auxetic metamaterials exhibit a negative Poisson’s ratio (NPR) through geometry-controlled deformation and offer considerable potential for impact energy absorption. This review systematically examines the structural configurations, deformation mechanisms, enhancement strategies and engineering applications of auxetic energy absorbers. Six representative topology families, including perforated, re-entrant, chiral, rotationally rigid, origami and other specialized structures, are reviewed in terms of their geometry, NPR mechanisms, collapse behavior and energy dissipation performance. Five major enhancement strategies are then evaluated, including baseline enhancement, optimization algorithms, multi-material integration, multi-structure integration and gradient design, with emphasis on their effects on load paths, peak force, plateau stability, densification and failure modes. A distinctive contribution is the quantitative synthesis of 37 paired, within-study comparisons of specific energy absorption (SEA). Reported SEA enhancements range from 6% to 800%, with a median of 81.5%, demonstrating the potential of structural innovation while revealing substantial variability among designs. The analysis indicates that NPR magnitude alone cannot determine energy absorption performance, as geometry, constituent material, relative density, loading conditions, manufacturing precision, environmental conditions and boundary constraints are also critical. Applications in aerospace, transportation, personal protection, biomedical devices and civil infrastructure are reviewed in relation to their functional requirements. Finally, current limitations and future directions are discussed, emphasizing integrated design strategies, manufacturing accuracy, performance under complex loading and environmental conditions, and the transition from laboratory concepts to practical engineering applications.