Format

Send to

Choose Destination
Materials (Basel). 2017 Feb 10;10(2). pii: E157. doi: 10.3390/ma10020157.

Boundary Layer Effect on Behavior of Discrete Models.

Author information

1
Brno University of Technology, Faculty of Civil Engineering, Veverˇí 331/95, Brno 60200, Czech Republic. elias.j@fce.vutbr.cz.

Abstract

The paper studies systems of rigid bodies with randomly generated geometry interconnected by normal and tangential bonds. The stiffness of these bonds determines the macroscopic elastic modulus while the macroscopic Poisson's ratio of the system is determined solely by the normal/tangential stiffness ratio. Discrete models with no directional bias have the same probability of element orientation for any direction and therefore the same mechanical properties in a statistical sense at any point and direction. However, the layers of elements in the vicinity of the boundary exhibit biased orientation, preferring elements parallel with the boundary. As a consequence, when strain occurs in this direction, the boundary layer becomes stiffer than the interior for the normal/tangential stiffness ratio larger than one, and vice versa. Nonlinear constitutive laws are typically such that the straining of an element in shear results in higher strength and ductility than straining in tension. Since the boundary layer tends, due to the bias in the elemental orientation, to involve more tension than shear at the contacts, it also becomes weaker and less ductile. The paper documents these observations and compares them to the results of theoretical analysis.

KEYWORDS:

boundary layer; concrete; discrete model; elasticity; fracture; wall effect

Supplemental Content

Full text links

Icon for Multidisciplinary Digital Publishing Institute (MDPI) Icon for PubMed Central
Loading ...
Support Center