冲击荷载作用下滤波混凝土的动态响应与层裂损伤数值研究

借鉴局域共振材料的工作机制，通过在混凝土基体中嵌入滤波单元，设计出具有应力波衰减特性的滤波混凝土。通过将滤波混凝土结构简化为质量弹簧力学系统来分析滤波混凝土对应力波的衰减机制。采用数值模拟方法，对比研究了冲击荷载作用下普通混凝土模型和滤波混凝土模型中应力波的传播特性和层裂破坏模式。通过参数分析，研究了滤波单元的材料和几何属性对其储能效果的影响。研究结果表明：滤波单元有效降低了混凝土基体中应力波的传播速度和应力峰值；滤波单元的储能机制有效降低了混凝土基体中的能量；金属球的质量越大，滤波单元的储能效果越好，但弹性层的弹性模量和厚度需要通过适当分析进行设计以实现滤波单元的储能最大化；滤波混凝土基体的局部损伤耗散了荷载中的大量能量，有效降低了结构自由面附近的破坏程度。

Numerical study on dynamic response and spall damage of filter concrete under impact load

Based on the working mechanism of local resonance materials, a filter concrete with stress wave attenuation characteristics is designed by embedding metal balls wrapped with elastic layer (filter units) in the concrete matrix. First, the stress wave attenuation mechanism of filter concrete is analyzed by simplifying the filter concrete structure into a mass-spring mechanical system. Then, the propagation velocity and peak stress of stress wave in normal concrete model and filter concrete model under impact load are compared by using numerical simulation approach. Through parameter analysis, the influence of the density of metal ball, elastic modulus and thickness of elastic layer on the energy storage of filter units are studied. Finally, the spalling damage patterns of normal concrete model and filter concrete model under impact load are compared. The results show that the filter units can effectively reduce the stress wave propagation velocity and magnitude of peak stress in the concrete matrix. The vibration of the metal balls and the deformation of the elastic layer form a good energy storage mechanism for filter units and effectively reduce the energy exerted by the impact load on the concrete matrix. The larger the mass of the metal balls, the better the energy storage effect of the filter units, while the elastic modulus and thickness of the elastic layer need to be designed through a proper analysis to maximize the energy storage of the filter units. The concrete matrix around the elastic layer has obvious stress concentration and local damage may occur, but the local damage of the filter concrete matrix dissipates a large amount of energy produced by the load, effectively reducing the degree of destruction near the free surface of the structure. Combined with the attenuation effect of the filter units on the stress wave, the filter concrete has achieved good impact resistance.