多材料 anti-tetra chiral 結構於準靜態壓縮下力學行為機制分析

Abstract

自然界中的仿生設計啟發出多種具備特殊力學行為的結構型態，其中具旋轉單元特性的負泊松比結構(如chiral與anti-tetra chiral)因具備高能量吸收與可回復性，逐漸受到結構工程與材料科學的關注。本研究聚焦於anti-tetra chiral 結構，設計五種剛柔材料交錯配置，探討多材料配置對結構吸能行為、平台穩定性與破壞機制的影響。我們以Stratasys J750 多材料列印機製作七組不同配置之試體，包含軟試體 Agilus Black、硬性試體 Vero Clear 以及五種多材料配置，分別為：半核心與韌帶配置（Half Core & Ligament）、全核心配置（Full Core）、全韌帶配置（Full Ligament）、橫向配置（Horizontal）與縱向配置（Vertical），進而透過力–位移曲線（Force–Displacement Curve）與應變變形行為（Strain-Induced Deformation Behavior）之分析，並輔以影像觀察，探討旋轉展開與局部屈曲等變形機制。結果顯示，當軟材料配置於旋轉主軸區域（如 Half Core & Ligament 與 Vertical 設計）時，可有效延長平台段並降低破壞集中現象。所有設計之試體皆採取對稱幾何設計，包括中心節點配置與韌帶排列方式，目的就是為了確保旋轉展開的一致性與力學行為穩定性，避免受力偏心或變形不均的情形發生。此外，我們以實測數據比較 （Specific Energy Absorption，單位質量能量吸收）、平台載重波動係數（ULC）、與形貌恢復效率（SRE, Shape Recovery Efficiency）等性能指標進一步分析不同材料配置下的吸能能力與結構回復表現。結果顯示，Vertical多材料設計在吸能與穩定性間達成最佳平衡。具體而言，Vertical試體之單位質量能量吸收值為 17996 J/m³，顯著高於其他試體；平台波動載重係數為 1.219。楊氏模數為（163.5 kPa）展現適中強度。整體而言，anti-tetra chiral 結構藉由區域材料配置策略，能達成具可程式化力學回應之目標，提供新一代防護性結構設計之參考依據。

Bio-inspired designs found in nature have led to the development of various structures with unique mechanical behaviors. Among them, negative Poisson’s ratio (NPR) structures characterized by rotational units—such as chiral and anti-tetra chiral designs—have attracted increasing attention in structural engineering and materials science due to their high energy absorption and recoverability. This study focuses on the anti-tetra chiral structure, designing five configurations with alternating rigid and flexible materials to examine how multi-material arrangements affect energy absorption, plateau stability, and failure modes. Seven types of specimens were fabricated using a Stratasys J750 multi-material 3D printer, including two pure-material designs—Agilus Black (flexible) and Vero Clear (rigid)—and five multi-material configurations: Half Core & Ligament, Full Core, Full Ligament, Horizontal, and Vertical. These specimens underwent uniaxial compression tests, with force–displacement curves and strain-induced deformation recorded throughout. Rotational motion and local buckling were analyzed via image-assisted observation. The results indicate that placing flexible materials near the rotational axis (as in the Half Core & Ligament and Vertical designs) effectively extends the plateau stage and mitigates localized failure. All specimens featured geometrical symmetry—including centrally arranged nodes and symmetric ligament layouts—to ensure consistent rotational unfolding and mechanical stability, thereby avoiding eccentric loading and uneven deformation. Performance metrics including Specific Energy Absorption (SEA), Undulation of Load-bearing Capacity (ULC), and Shape Recovery Efficiency (SRE) were evaluated to compare energy absorption and recoverability across configurations. The Vertical design demonstrated the best balance between energy absorption and structural stability, achieving an SEA of 17,996 J/m³, a ULC of 1.219, and a Young’s modulus of 163.5 kPa—indicating moderate stiffness. Overall, the anti-tetra chiral structure illustrates the potential of programmable mechanical responses through region-specific material placement strategies, offering valuable insights for the design of next-generation protective structures.