Isotropic random fracture model for metal hydride powder
Particle morphology and size distribution of metal hydride powders
Metal hydrides can be used to store hydrogen on-board fuel cell vehicles, but the process of fracture which such the material undergoes when exposed to hydrogen makes such materials poor conductors of heat. The fracture process by which particles are generated have irregular faceted shapes, which are difficult to describe quantitatively from experimental data.
Isotropic random fracture model
In a recently published conference paper we [1] presented a model for predicting the distribution of particle shape and size exhibited by metal hydride powders. The isotropic random fracture model assumes (1) planar surfaces are formed from instances of fracture, (2) planes of fracture have isotropic statistical orientation and position throughout the material, and (3) fracture of any individual particle terminates after some critical volume is reached during the sequential fracture process.
Accessing the tool
The model was implemented in MATLAB and is freely available as a thermalhub tool. To access this computational tool, download and unzip the file rndmfrc.zip (go to [2] to download). This file contains the main program, rndmfrc.m, which you should run. The other programs are required subfunctions. The tool also utilizes 3D [3] and 2D [4] geometry toolboxes developed by David Legland and these libraries must be downloaded to run rndmfrc.m. Note that geom2d and geom3d are licensed under the GNU license.
Sample output
- Particle size distributions
- Particle surface area distributions
- Particle shape data structure
– Arbitrarily shaped convex polyhedra area formed by this model, and as such the data format must accomodate it.
– A main cell array for all particle vertices is stored under the variable verts. The vertices of a particular particle, i, are stored in verts{i}.
– Likewise a main cell array which contains the links between vertices and faces for each particle is stored under the variable fs. The edges of a particular particle, i, are stored in fs{i} as a cell array itself. Each entry of fs{i} contain row vectors corresponding to each face on particle i. The entries of each row vector contain the vertices belonging to the particular face of particle i.