VGeST - Virtual Geoscience Simulation Tools

Particle shape library

The majority of the research required to create an effectively functioning shape library software package, P3D was done by Dr. Xavier Garcia as a by-product of his PhD research at Imperial College under the supervision of Dr. J-P Latham in consultation with Antonio Munjiza.

Numerical simulation that will capture the complex behaviour of rock fragment systems e.g. in mining and civil engineering, or systems with biological shapes or man-made geometries requires both the computational mechanics capability to model particle interactions between complex shapes and an associated means to represent the kind of arbitrary or angular geometries. In VGeST we have DEM and FEMDEM solvers to perform the mechanics. The other core technology specifically developed to facilitate pre-processing, rescaling and exporting to the computational domain is the Particle Shape Library, P3D.

P3D is a virtual repository containing many surface and volumetric meshes of real aggregate particles. 3D laser ranging (LADAR) was used to capture astonishingly realistic rock aggregate geometries. Most appropriate for storing in the library for the purpose of computational modelling use are the lower resolution meshes.

15979 n, 31954 t

3474 n, 6944 t

917 n, 1836 t

298 n, 593 t

Some of the original granite aggregate rock shapes captured for use in the library are shown here:

The meshes are held in a database that allows great flexibility to both visualise the particle of your choice, to rescale it, select a sample of particles and export them for simulation purposes. A host of shape descriptors are also available in the database for detailed shape distribution analysis which may include any new particle geometries to be added to the library. Of critical importance to simulating the motion of the arbitrary shaped bodies or particles is the set of moments of inertia of each particle. These are computed and supplied automatically using the shape library. The inertia moments also supply an objective measure of particle axial dimentions. They are given by the ellipsoid axial lengths with identical moments of inertia to the particle.

An example of the types of information given from four different particles considered by the shape library tools is shown in the table below:

Further information on the Shape library is given in P3D.pdf and in Latham et al. (2008).

References

Latham, J.P., Munjiza, A., Garcia, X., Xiang, J., Guises, R. 2008.  Three-dimensional particle shape acquisition and use of shape library for DEM and FEM/DEM simulation. Minerals Engineering, 21 (11), 797-805, Oct 2008. doi:10.1016/j.mineng.2008.05.015

Dr Xavier Garcia, PhD Thesis, 2010.