Architected Lattices with Adaptive Energy Absorption

Energy absorbing materials, like foams used in protective equipment, are able to undergo large deformations under low stresses, reducing the incoming stress wave below an injury or damage threshold. They are typically effective in absorbing energy through plastic deformation or fragmentation. However, existing solutions are passive, only effective against specific threats and they are usually damaged after use. Here, we overcome these limitations designing energy absorbing materials that use architected lattices filled with granular particles. We use architected lattices to take advantage of controlled bending and buckling of members to enhance energy absorption. We actively control the negative pressure level within the lattices, to tune the jamming phase transition of the granular particles, inducing controllable energy absorption and recoverable deformations. Our system shows tunable stiffness and yield strength by over an order of magnitude, and reduces the transmitted impact stress at different levels by up to 40% compared to the passive lattice. The demonstrated adaptive energy absorbing system sees wide potential applications from personal protective equipment, vehicle safety systems to aerospace structures.

吸能材料（如防护装备中使用的泡沫）可在低应力下发生大变形，将入射应力波降至损伤阈值以下。这类材料通常通过塑性变形或碎裂实现高效吸能。然而，现有方案均为被动式，仅对特定威胁有效，且使用后常发生损坏。在此，我们通过设计填充颗粒的结构晶格吸能材料，克服了上述局限。我们利用结构晶格构件的受控弯曲与屈曲特性，以提升吸能效率。通过主动调控晶格内的负压水平，我们可调节颗粒的阻塞相变（jamming phase transition），实现可控吸能与可恢复变形。该系统的刚度与屈服强度可调范围超过一个数量级，且在不同冲击级别下，相较于被动晶格，其传递冲击应力最多可降低40%。这种自适应吸能系统在个人防护装备、车辆安全系统及航空航天结构等领域具有广泛应用潜力。