Influence of particle packing structure on sound velocity

• 来源期刊: 中国物理B（英文版）
• 关键词: discrete element method acoustic propagation packing structure stiffness tensor
• 年，卷（期）: 2018,（10）
• 页码范围: 323-332
• 页数: 10页
• 语种: 英文
• DOI: 10.1088/1674-1056/27/10/104501

摘要

The anisotropy in the particle systems of different packing structures affects the sound velocity. The acoustic propa-gation process in four kinds of packing structures (denoted as S45, H60, S90, and D) of two-dimensional granular system is simulated by the discrete element method. The velocity vtof obtained by the time of fl ight method and the velocity vc obtained from the stiffness tensor of the system are compared. Different sound velocities refl ect various packing structures and force distributions within the system. The compression wave velocities of H60 and S90 are nearly the same, and trans-mit faster than that of D packing structure, while the sound velocity of S45 is the smallest. The shear wave velocities of S45 and H60 are nearly the same, and transmit faster than that of D packing structure. The compression wave velocity is sensitive to the volume fraction of the structure, however, the shear wave velocity is more sensitive to the geometrical structure itself. As the normal stress p is larger than 1 MPa, vtof and vc are almost equal, and the stiffness tensors of various structures explain the difference of sound velocities. When the normal stress is less than 1 MPa, with the coordination number unchanged, the law vtof∝p1/4 still exists. This demonstrates that apart from different power laws between force and deformation as well as the change of the coordination number under different stresses, there are other complicated causes of vtof∝p1/4, and an explanation of the deviation from vtof∝p1/6 is given from the perspective of dissipation.