Structural and Mechanical Properties of Nanopowders

纳米粉末是由纳米粒子组成的颗粒状系统，它们的短程相互作用主要受强大的粘附力范德华作用力的支配。这些吸引力是纳米颗粒聚集成分叉结构形成微米大小的薄片的原因。在宏观尺度上，纳米粉末似乎是均匀的，而在微观尺度上，它们呈现出分形结构。本研究项目的目的是开发数值方法来模拟纳米粉末的渐近结构，因为它在重复的破碎和沉积过程中演变。ii)基于3D(对于某些方面也在2D中)的大规模数值模拟来表征纳米粉末的结构特性，包括分形特性、各向异性等。尤其是纳米颗粒的体积和表面特性的影响，例如极性、电荷、润湿、吸附以及溶剂的特性。iii)为了研究纳米粉末的宏观特性，如本构关系、屈服行为、冲击减振性能、声传输等)来解释纳米粉末的统计特性，如接触力统计和块体和表面的分形特性。

Nanopowders are granular systems of nanometer-sized particles whose short range interaction is dominated by strong adhesive van-der-Waals forces. These attractive forces are the reason why nano-particles agglomerate into ramified structures forming micrometer-sized flakes. On a macroscopic scale, nanopowders appear to be homogeneous while on a microscopic scale they reveal a fractal structure.The aims of this research project arei) to develop numerical methods for the simulation of the asymptotic structure of nanopowders, as it evolves in repeated break and deposition processes ii) to characterize the structural properties of nanopowders based on large-scale numerical simulations in 3d (for certain aspects also in 2d), including fractal properties, anisotropy etc. In particular the influence of volume and surface properties of nano particles such as polarity, charges, wetting, adsorbates as well as the properties of the solvent shall be addressed.iii) to investigate the macroscopic properties of nanopowders, such as constitutive relations, yield behavior, impact-damping properties, and sound transmission iv) to explain the statistical properties of nano-powders such as contactforce statistics and fractal properties of the bulk and surface.