半约束条件下薄壁金属圆柱的流固耦合作用与水下静水内爆
Fluid-Structure Interaction and Underwater Hydrostatic Implosion of Thin-Walled Metallic Cylinders in Semi-Confined Conditions
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中文总结 AI 辅助
本研究采用LS-DYNA的ALE方法对半约束金属圆柱的流固耦合与静水坍塌开展数值研究，揭示了材料、长细比、约束直径对坍塌行为的影响，为水下结构设计提供定量指导。
中文摘要 AI 辅助
本研究采用LS-DYNA中的结构化任意欧拉-拉格朗日（ALE）公式，对半约束流体环境中发生静水坍塌的金属圆柱的动态行为及流固耦合（FSI）作用开展了全面的数值研究。数值模型复现了实验测得的3.69 MPa坍塌压力，且预测的首次水锤峰值误差为1.01%，展现出极高的预测保真度。经验证后，研究考察了材料类型（铝和钛）、圆柱长细比（L/D）以及约束直径对坍塌行为、压力演化和流体运动的影响。由于钛的刚度和屈服强度更高，钛圆柱的坍塌更剧烈，产生的水锤压力超过70 MPa，且动能和应变能积累比铝圆柱更多。较低的L/D比会产生更突然的坍塌，而较高的L/D比则促使变形更平缓、呈轴对称。较大的约束直径会加剧射流形成并提高流体速度。这些模拟为结构变形与周围流体之间的耦合提供了机理性认识，表明几何形状、材料刚度和约束条件决定了坍塌引发的能量传递。全场FSI分析捕捉到了径向射流、峰值流体速度和内部空化等关键现象，这些现象仅从压力-时间历程中无法明显观察到。研究结果为海底压力壳体、海洋管道及其他承受极端静水载荷的水下结构的设计和安全评估提供了定量指导。
英文摘要
This study presents a comprehensive numerical investigation of the dynamic behavior and fluid-structure interactions (FSI) of metallic cylinders undergoing hydrostatic collapse in semi-confined fluid environments using a structured Arbitrary Eulerian-Lagrangian (ALE) formulation in LS-DYNA. The numerical model reproduces the experimentally measured collapse pressure of 3.69 MPa and predicts the first water hammer peak with a 1.01% error, demonstrating high predictive fidelity. Following validation, the effects of material type (aluminum and titanium), cylinder slenderness ratio (L/D), and confinement diameter on collapse behavior, pressure evolution, and fluid motion are examined. Titanium cylinders exhibited sharper collapses, higher water hammer pressures exceeding 70 MPa, and greater kinetic and strain energy accumulation than aluminum due to their higher stiffness and yield strength. Lower L/D ratios produced more abrupt collapses, whereas higher L/D ratios promoted more gradual, axisymmetric deformation. Larger confinement diameters intensified jet formation and increased fluid velocities. The simulations provide mechanistic insight into the coupling between structural deformation and surrounding fluid, showing that geometry, material stiffness, and confinement govern collapse-induced energy transfer. Full-field FSI analysis captures key phenomena, including radial jetting, peak fluid velocities, and internal cavitation, that are not evident from pressure-time histories alone. These findings provide quantitative guidance for the design and safety assessment of subsea pressure housings, marine pipelines, and other underwater structures subjected to extreme hydrostatic loading.
