泡沫铝夹层结构抗冲击性能的近场动力学模拟分析

针对某光学舱所采用的泡沫铝夹层防护结构在破片冲击下的抗冲击性能问题，采用Monte-Carlo方法创建了泡沫铝结构的二维细观模型，在常规态型近场动力学理论中引入了Mises屈服准则和线性各向同性强化模型，建立了近场动力学塑性本构的数值计算框架。基于近场动力学计算程序模拟了低速冲击作用下泡沫铝夹层结构的塑性变形以及有机玻璃背板的裂纹扩展形态，分析了泡沫铝芯材孔隙率对该夹层结构抗冲击性能和损伤模式的影响规律。结果表明：泡沫铝夹层结构良好的塑性变形能力是其发挥缓冲与防护作用的主要因素，并且在一定范围内，泡沫铝芯材孔隙率越高，则夹层结构具有更好的抗冲击性能；当泡沫铝孔隙率从0.4提升到0.7时，泡沫铝对冲击物的动能吸收率从90%提高到99%；模拟结果与实验结果具有较好的一致性，验证了模拟结果的准确性和分析结论的有效性。通过数值模拟，预测了有机玻璃背板的裂纹扩展形态，发现提高泡沫铝的孔隙率能获得更好的防护效果。

Simulation analysis on impact resistance of aluminum foam sandwich structures using peridynamics

Under impact, aluminum foam undergoes significant plastic deformation, and the kinetic energy of the impactor is dissipated in the process, thereby protecting the structure from damage. The failure modes of aluminum foam sandwich structures under impact are complex, involving plastic deformation, panel failure, and cracking of the bonding interface. Traditional numerical simulation methods are difficult to solve these discontinuous problems. Peridynamics is a non-local numerical method that describes the mechanical behavior of materials by solving spatial integral equations. It has unique advantages in solving crack propagation, material failure, progressive damage of composite materials, and multi-scale problems. Although the basic bond-based peridynamic theory cannot describe plasticity, the ordinary state-based peridynamic method decouples distortion and dilation and can easily simulate the plastic deformation of materials. Therefore, based on ordinary state-based peridynamics, the Mises yield criterion and the linear isotropic hardening model were introduced to study the factors affecting the impact resistance of aluminum foam sandwich structures. Two-dimensional mesoscopic models of aluminum foam sandwich structure were established by the Monte-Carlo method and impact was simulated using the peridynamic method. The influence of the porosity of aluminum foam on the impact resistance and damage mode of the sandwich structure was analyzed. The results show that the good plastic deformation ability of aluminum foam sandwich structure is the main factor for its buffering and protection, and within a certain range, the higher the porosity of aluminum foam core, the better impact resistance of the sandwich structure. When the porosity of aluminum foam increases from 0.4 to 0.7, the kinetic energy absorption rate of aluminum foam to the impactor increases from 90% to 99%. The simulation results are in good agreement with the experimental results, which verifies the accuracy of the simulation results and the effectiveness of the analysis conclusions. The numerical simulation predicts the crack propagation morphology of the plexiglass backplate, and the results show that improving the porosity of aluminum foam can obtain a better protection effect.