Enhanced Mesh-Free Simulation of Regolith Flow

Award Information
Agency: National Aeronautics and Space Administration
Branch: N/A
Contract: NNX11CE33P
Agency Tracking Number: 105044
Amount: $100,000.00
Phase: Phase I
Program: SBIR
Awards Year: 2011
Solitcitation Year: 2010
Solitcitation Topic Code: X1.01
Solitcitation Number: N/A
Small Business Information
Grainflow Dynamics, Inc.
1141 Catalina Drive, PMB 270, Livermore, CA, -
Duns: 193084980
Hubzone Owned: N
Woman Owned: N
Socially and Economically Disadvantaged: N
Principal Investigator
 Scott Johnson
 Principal Investigator
 (617) 851-7107
 scott.johnson@grainflow.com
Business Contact
 Otis Walton
Title: Business Official
Phone: (925) 447-4293
Email: walton@grainflow.com
Research Institution
 Stub
Abstract
NASA needs simulation tools capable of predicting the behavior of regolith in proposed excavation, transport, and handling or sample acquisition systems. For engineering-scale problems FE analyses utilizing soil-mechanics-based constitutive models have long been utilized in civil engineering to evaluate stresses and deformations up to failure, even including some plastic flow. The extremely large strains, bulking and recompaction behavior in excavation, hopper flow and regolith processing, however, are generally beyond the capability of most FE codes. Mesh-free methods offer an attractive optionÂ? especially when coupled with critical-state soil-mechanics based constitutive models allowing unlimited shear deformation and flow. This Phase-1 project will enhance a new mesh-free SPH-based simulation model, initiated as part of an earlier SBIR project, to demonstrate its potential to meet NASA's need for a robust simulation tool for regolith manipulation and flow. Enhancements include providing smooth transitions as new free surfaces are created, parallelized algorithms so that high resolution can be maintained as the physical scale of the problems is increased to realistic engineeringsizes, and inclusion of realistic cohesion in the critical-state soil-mechanics constitutive model. The large fraction of very fine particulates in lunar and Martian regoliths (e.g., particles<20-microns) precludes particle-scale DEM models from ever being able to both maintain particle-scale fidelity and simulate engineering-scale problems. Utilization of larger-than-nature 'calculational particles' in DEM code leads to new challengesÂ? calibration of those 'particles' so that the calculational material will reproduce the constitutive behavior of the original granular assembly. The mesh-free SPH model developed here has the potential to become a new robust simulation tool to address NASA's challenging regolith manipulation andflow problems.

* information listed above is at the time of submission.

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