Accession Number : ADA627192


Title :   Toward Theoretical Foundations of Resistive Force Theory of Granular-Structural Interaction, with Expansions to Flexible Locomotors


Descriptive Note : Final rept. 1 Jul 2014-31 Mar 2015


Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE


Personal Author(s) : Kamrin, Ken ; Askari, Hesam


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA627192


Report Date : 07 May 2015


Pagination or Media Count : 20


Abstract : Granular Resistive Force Theory (RFT) is a reduced-order model inspired by analogous boundary-integral methods for Stokesian fluids. Despite its remarkable capability to predict experimental locomotion and force distributions on mobile bodies in granular media, there is no theoretical understanding for this behavior. Moreover, such a reduction is surprising given the highly nonlinear constitutive behavior of granular media. There could be a variety of reduced-order applications in various structure/granular interactions if a theoretical picture in explanation of RFT could be uncovered. Moreover, as with any accurate and sufficiently reduced model, RFT, once its limitations and backing is better understood, could be used as a reliable design-optimization tool to produce locomotors with optimal shapes, or tunable flexibility to improve efficiency of locomotion within granular media. The flowability of loose terrain under solid intrusion produces complex dynamics in problems ranging from geotechnical design to animal and vehicle locomotion. One approach is the Resistive Force Theory (RFT), a recent empirical tool for predicting granular-structure interaction. Its simplicity and effectiveness are surprising given the many complexities of granular ow, begging fundamental questions of why RFT works. We have found a link between RFT and plasticity theory, showing RFT arises solely from frictional yielding. Without any fitting, plasticity generates experimental RFT data, and reproduces RFT's foundational assumptions including spatial force superposition.


Descriptors :   *FRICTION , *GRANULAR MATERIALS , *SOIL RESISTANT PROPERTIES , *TERRAIN , APPROXIMATION(MATHEMATICS) , BOUNDARY ELEMENT METHODS , COMPUTATIONS , COUPLING(INTERACTION) , CURVATURE , GEOPHYSICS , HYDRODYNAMICS , LOCOMOTION , MATHEMATICAL PREDICTION , MOMENTUM , NONLINEAR SYSTEMS , OPTIMIZATION , PARTIAL DIFFERENTIAL EQUATIONS , PLASTIC PROPERTIES , SPATIAL DISTRIBUTION , TREADS


Subject Categories : Geology, Geochemistry and Mineralogy
      Soil Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE