Title:
Granular impact and the critical packing state
Granular impact and the critical packing state
Author(s)
Umbanhowar, Paul B.
Goldman, Daniel I.
Goldman, Daniel I.
Advisor(s)
Editor(s)
Collections
Supplementary to
Permanent Link
Abstract
Impact dynamics during collisions of spheres with granular media reveal a pronounced and nontrivial dependence on volume fraction ϕ. Postimpact crater morphology identifies the critical packing state ϕcps, where sheared grains neither dilate nor consolidate, and indicates an associated change in spatial response. Current phenomenological models fail to capture the observed impact force for most ϕ; only near ϕcps is force separable into additive terms linear in depth and quadratic in velocity. At fixed depth the quadratic drag coefficient decreases (increases) with depth for ϕ<ϕcps (ϕ>ϕcps). At fixed low velocity, depth dependence of force shows a Janssen-type exponential response with a length scale that decreases with increasing ϕ and is nearly constant for ϕ>ϕcps.
Sponsor
Date Issued
2010-07-15
Extent
Resource Type
Text
Resource Subtype
Article