Auxetic structures for energy absorption: A review on design, manufacturing, optimization, and applications

Auxetic structures, distinguished by their unique deformation behaviors, exhibit remarkable mechanical properties, including superior energy absorption capacity, high indentation resistance, enhanced toughness, and excellent surface conformability. Compared to conventional honeycomb or foam materials, auxetic configurations can reduce peak stress by 20%–40%, extend the stress plateau by up to 60%, and enhance densification resistance by over 30%, making them highly suitable for impact, blast, and crash energy mitigation. This review systematically summarizes recent developments in the design, optimization, and manufacturing of auxetic structures for energy absorption purpose. Among various unit-cell topologies, modified re-entrant offer high specific energy absorption under quasi-static loading, while rotating and hierarchical designs demonstrate superior performance in multi-directional and dynamic scenarios. Optimization strategies, ranging from topology optimization to surrogate-assisted machine learning, enable precise tailoring of energy absorption profiles. Additionally, advances in additive manufacturing and modular assembly facilitate the scalable fabrication of complex auxetic geometries. This review highlights the correlations between structural features and energy absorption efficiency and proposes guidelines for selecting geometry, material, and fabrication strategies based on application-specific requirements. By integrating quantitative comparisons and performance-driven insights, this work aims to support the development and deployment of next-generation auxetic energy absorbers in engineering practice.