氧化硅气凝胶粉体材料力学性能的多尺度模拟

Multi-Scale Simulation on Mechanical Properties of Silica Aerogel Powder

基于氧化硅气凝胶粉体材料内部的微结构特征,建立了能反映其特征结构的多尺度力学模型,利用分子动力学方法模拟了氧化硅气凝胶的纳米多孔结构和拉伸性能,进一步利用离散元方法模拟了粉体材料的模压成形和多轴压缩应力-应变曲线。分子动力学模拟表明,气凝胶密度越低,其分形维数越小。此外,离散元模拟表明,氧化硅气凝胶粉体材料的弹性模量比对应的氧化硅气凝胶弹性模量低,压缩强度比对应气凝胶的拉伸强度高;随着围压的增加,氧化硅气凝胶粉体材料的压缩强度增加。

Based on the microstructure of silica aerogel powder, a multi-scale model revealing the internal fea- ture of real material is constructed. The nanoporous structure and tensile properties of silica aerogel is simulated using molecular dynamic （MD） model. The compression molding of silica aerogel powder is modeled using discrete element method （ DEM）, and then the multiaxial compressive curve of real material is simulated. The MD simulation indicates the fraetal dimension of silica aerogel decreases as the density increases. Moreover, the DEM simulation reveals the e- lastic modulus of silica aerogel powder is larger than that of silica aerogel while the compressive strength of silica aero- gel powder is lower than that of silica aerogel. The compressive strength of silica aerogel powder increases as the confi- ning stress increases.