The majority of the research required to create an effectively functioning shape library software package, hosted by Sourceforge within the VGW package was created by Dr Xavier Garcia as a by-product of his PhD research at Imperial College.
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 Solidity, both deformable and rigid versions of the FEMDEM solver are used to perform the mechanics. The Particle Shape Library is core technology specifically developed to facilitate pre-processing, rescaling and exporting to the computational domain.
The Particle Shape Library is a virtual repository containing many surface and volumetric meshes of real aggregate particles. 3D laser ranging (LIDAR) was used to capture astonishingly realistic rock aggregate geometries. The most appropriate meshes for storing in the library for the purpose of computational modelling of natural rock-like and mineral-like particles are the lower resolution meshes. The library can be added to using further geometries captured by e.g. X-Ray CT Scans or polyhedral slicing algorithms.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 re-scale 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, when adopting the rigid version of the solver rather than the fully deformable version, 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 dimensions. They are given by axial lengths of the ellipsoid 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
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), p.797-805, Oct 2008. doi:10.1016/j.mineng.2008.05.015
Dr Xavier Garcia 2009, PhD Thesis, Imperial College London