Department Seminar of Dr' Yoav Polak -Force calculation and Force Chains in Jammed Granular Media
School of Mechanical Engineering Seminar
Monday, March 5, 2018 at 14:00
Wolfson Building of Mechanical Engineering, Room 206
Force calculation and Force Chains in Jammed Granular Media
Yoav G. Pollack
Jacques Zylberg1, Oleg Gendelman2, Shiladitya Sengupta1 and Itamar Procaccia1
1Dept. of Chemical Physics, The Weizmann Institute of Science, Rehovot, Israel.
2Faculty of Mechanical Engineering, Technion, Haifa, Israel.
Granular materials are large conglomerations of discrete macroscopic frictional particles such as
sand, cement, grain, co_ee grounds and powders. These can ow under strain, but under compres-
sion undergo a critical jamming transition into a disordered solid that can sustain a load. Force
chains are the intricate anisotropic networks of large contact forces that permeate a stressed jammed
medium and are responsible for its rigidity. Unfortunately the measurement of contact forces in such
jammed systems (e.g. in photo-elastic disks) is of unsatisfactory precision . In this talk I will
present a new formalism to compute all the contact forces, both normal and frictional, that em-
ploys only the knowledge of the orientations of contacts between particles, but crucially not the
harder to measure exact positions. Furthermore I will show that the force chains in such systems
are determined by an expansion in the eigenfunctions of a newly de_ned operator.