Toward Theoretical Foundations of Resistive Force Theory of Granular-Structural Interaction, with Expansions to Flexible Locomotors
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 07, 2015
- Accession Number
- ADA627192
Entities
People
- Hesam Askari
- Ken Kamrin
Organizations
- Massachusetts Institute of Technology