Discrete Element Modeling

NASA: Simulation of Lunar Regolith

ITR/AP: Simulation of Machine-Medium Interaction in a Real-Time Virtual Environment

Sponsor: National Science Foundation

This project is a joint multidisciplinary industry-academia research effort to develop an advanced virtual reality (VR) environment for modeling earthmoving equipment interaction with the surrounding medium such as soil. The project will take advantage of rapid developments in hardware, software and information technology to develop a real-time virtual environment for machine-medium interaction that includes realistic force-feed back. The proposed development will enhance the design of the earthmoving equipment and improve the design cycle. It will also open up new venues for application of VR for machine medium interaction. This project will greatly benefit from leveraged resources provided by Caterpillar, Inc. The research team will develop an original neural network (NN) based real-time soil medium model that can be used to simulate soil response due to manipulation by earthmoving equipment. The proposed model will be mechanistically accurate and run in real-time. It will simulate the soil resistance and the interactive forces between the medium and the earthmoving equipment. The NN model will be trained using data sets developed from non-real time simulations using the discrete element method. Data sets of soil and earthmoving equipment response will also be developed from full-scale field tests at Caterpillar, Inc. proving ground in Peoria, Illinois. The research team, in cooperation with the National Center for Supercomputing Applications (NCSA), will implement the new NN soil model in Cave Automated Virtual Environment (CAVE). A new object-oriented vehicle prototyping system (VPS) will be developed in this virtual environment. A force feedback link will be developed representing the medium resistance provided by the NN soil model to the vehicle dynamics model. The real-time virtual environment will enhance the design verification tools available to the earthmoving equipment manufacturing industry and reduce the number of costly field trials for new equipment designs. The ideas and methodology that will be developed for the real-time VR environment have a wide range of applications such as simulation of slope failures and avalanches as well as bulk and powder material handling in agricultural, mining and manufacturing applications. The proposed VR environment can potentially be used in space exploration of other planets where it is necessary to troubleshoot a remote controlled vehicle interacting with the soil medium on the planetary surface in real-time. This project brings together specialists in 1) computational intelligence and soil medium modeling from the Department of Civil and Environmental Engineering at UIUC, 2) virtual reality and computer science from NCSA at UIUC, and 3) earthmoving equipment design and control at Caterpillar, Inc. Close coordination among the team members will ensure a strong exchange of ideas between academia and industry.

Ph.D. Thesis

Nezami, E. G. (2007). “THREE-DIMENSIONAL SIMULATION OF GRANULAR MATERIALS USING DISCRETE ELEMENT METHODS,” Ph.D. Thesis, University of Illinois at Urbana-Champaign, Urbana.

References:

Nezami, E. G., Hashash, Y. M. A., Zhao, D., and Ghaboussi, J. (2007). “Simulation of front end loader bucket-soil interaction using discrete element method.” International Journal for Numerical and Analytical Methods in Geomechanics, 31(9), pp. 1147 – 1162.

Zhao, D., Nezami, E. G., Hashash, Y. M. A., and Ghaboussi, J. (2006). “Three-dimensional discrete element simulation for granular materials.” Engineering Computations, 23(7), pp. 749-770.

Erfan G. Nezami, Y. M. A. H., Dawei Zhao, Jamshid Ghaboussi, (2006). “Shortest link method for contact detection in discrete element method.” International Journal for Numerical and Analytical Methods in Geomechanics 30(8): 783 – 801.

Hashash, Y. M. A., E. Nezami, Z. Dawei and J. Ghaboussi (2005). DBLOCK3D: A 3-D discrete element analysis code for simulation of granular media and soil-machine interaction. NASA Workshop on Granular Materials in Lunar and Martian Exploration, Kennedy Space Center, Florida.

Nezami, E. and Y. M. A. Hashash (2002). The use of static discrete element method to simulate biaxial compression test. 3rd International Conference on Discrete Element Methods, Santa Fe, NM, ASCE.

Nezami, E., Y. M. A. Hashash, D. Zhao and J. Ghaboussi (2004). “A fast contact detection algorithm for 3-D discrete element method.” Computers and Geotechnics 31: 575-587.

Nezami, E., D. Zhao, Y. M. A. Hashash, G. Bauer, D. Raila and J. Ghaboussi (2006). Large Scale Numerical Simulation via Parallelization and Reconfigurable Computing Hardware. Geotechnical Engineering in the Information Technology Age, Atlanta, ASCE.

Nezami, E. G., Y. M. A. Hashash and J. Ghaboussi (2006). A Model for Large-Scale Near-Real Time Simulation of Granular Material Flow. Earth & Space 2006, Houston, TX, ASCE.

Nezami, E. G., D. Zhao, Y. Hashash and J. Ghaboussi (2005). Shortest Link Method for Contact Detection in 3D DEM Simulations. 8th US National Congress on Computational Mechancis, Austin, TX.

Zhao, D., E.Nezami, Y. M. A. Hashash and J. Ghaboussi (2006). Discrete Element Modeling of Polyhedral Representation of Granular Materials. Earth & Space 2006, Houston, TX, ASCE.