| 摘要: | 分子動力學(Molecular Dynamics，MD)模擬是一種以牛頓力學為基礎的計算方法，用以模擬原子或分子在特定條件下的運動行為。透過設定原子間適當的勢能函數（如embedded atom method，EAM、Lennard-Jones potential，LJ等），分子動力學能夠捕捉皮秒至奈秒等極短時間內的粒子動態演化，進而揭示傳統宏觀分析中難以觀察到在奈米尺度下的原子級結構演化與破壞機制。
本研究利用分子動力學模擬探討奈米顆粒金屬板材在剪切與高速穿刺載荷下的動態行為，藉由觀察奈米顆粒排列及晶體結構演化，深入探討顆粒間鍵結、晶體結構重新排列等現象。模擬的材料包含鋁、鈦與鈦鋁合金，分別建立單層與雙層奈米顆粒板，進行系統性剪切與穿刺行為分析，並進一步比較不同彈體幾何形狀（圓球形與圓柱形）對破壞行為的影響。
結果顯示由鋁所組成的奈米顆粒板抗彈道衝擊能力的表現最差，原因為鋁材料本身抗剪能力較弱，且從晶體結構分析中觀察到鋁板在受到彈體穿刺時破壞面周圍幾乎未出現滑動與差排行為，顯示鋁板在能量消耗方面不足。反觀鈦鋁合金板具有較高之剪切模數且明顯之應變硬化階段，在綜合抗剪強度上及能量的消耗上優於鈦板及鋁板，使得鈦鋁合金板抗彈道衝擊能力表現最強。
藉由穿刺過程中的破壞演化機制以及材料最終的損傷形貌結果，不僅有助於理解奈米尺度下金屬粉末顆粒所形成的金屬板在極端動態載荷下的力學行為，更對未來奈米防護材料之設計具有高度應用價值。針對不同威脅場景，選擇適當的材料組成與結構配置，並考量可能遭遇之彈體形狀與能量條件，將有助於提升微尺度防護元件的性能與可靠性。
關鍵詞:分子動力學、勢能函數、金屬奈米顆粒板、彈道衝擊
;Molecular Dynamics (MD) simulation is a computational approach based on Newtonian mechanics, used to simulate the motion behavior of atoms or molecules under specific conditions. By defining appropriate interatomic potential functions, such as the Embedded Atom Method (EAM) and the Lennard-Jones (LJ) potential, MD can capture atomic-scale dynamic evolution within extremely short timescales ranging from picoseconds to nanoseconds. This enables the investigation of structural evolution and failure mechanisms at the nanoscale, which are often unobservable in traditional macroscopic analyses.
This study employs MD simulations to investigate the dynamic behavior of metallic nanoparticle-based plates under shear and high-velocity penetration loads. By observing the nanoparticle arrangements and the evolution of crystal structures, this research explores phenomena such as interparticle bonding and crystal reorientation. The materials studied include aluminum (Al), titanium (Ti), and a titanium-aluminum (Ti-Al) alloy. Both single-layer and double-layer nanoparticle plates are modeled to systematically analyze their shear and penetration responses. Additionally, the effects of different projectile geometries, specifically spherical and cylindrical shapes, on failure behavior are compared.
The results indicate that Al nanoparticle plates exhibit the weakest ballistic resistance. This is primarily due to the inherently low shear strength of aluminum. Crystallographic analysis reveals a lack of dislocation activity and slip around the damage zone during projectile penetration, suggesting limited energy dissipation. In contrast, the Ti-Al alloy plates demonstrate superior performance due to their higher shear modulus and a more prominent strain-hardening phase. As a result, the Ti-Al alloy outperforms both Ti and Al in terms of shear resistance and energy absorption, exhibiting the strongest ballistic resistance.
By examining the failure mechanisms during the penetration process and analyzing the final damage morphology of the materials, this study provides valuable insights into the mechanical behavior of metallic nanoparticle plates under extreme dynamic loads. These findings offer important guidance for the future design of nanoscale protective materials. Selecting appropriate material compositions and structural configurations, while considering possible projectile shapes and impact energy conditions, can help improve the performance and reliability of microscale protective components in various threat scenarios.
Keywords: Molecular Dynamics, Potential Function, Metallic Nanoparticle Plate, Ballistic Impact. |
