SNBV Support Support Download Files

The SNBV (Subspring Network Breakable Voronoi) modeling support package (snbvPkg) supports using the Subspring Network Breakable Voronoi model that includes material creation and laboratory testing (direct-tension and triaxial/biaxial in 3D/2D). The capability is provided in the snbvPkg9.N package that works with PFC version 9 (where N is the package subversion number. The SNBV model is a type of bonded-particle model and support for constructing other types of bonded-particle models is provided by the material modeling support package.

Potyondy, D. (2026). SNBV Support (Subspring Network Breakable Voronoi model) for PFC [snbvPkg9.5]. Itasca Consulting Group, Inc., Technical Memorandum 5-8106:25TM06 (July 9, 2026).

Download Files

PFC 9.0

SNBV-Modeling Support Package, snbvPkg9.5 (ZIP, 5 MB)

SNBV-Modeling Support Update Revisions

The first column of this table lists the snbvPkg revision number; the second column lists the PFC release against which the snbvPkg has been tested; and the third column describes the snbvPkg revision. Note that each revision of the snbvPkg is expected to operate with a PFC release that is current or newer than that listed. Since newer revisions of the snbvPkg may use features available only in newer revisions of PFC, they may not be compatible with older revisions of PFC.

snbvPkg Release	PFC Release	Date / Description
9.5	9.7.48	07/09/26 Add ability to create and test PFC2D SNBV material (see SNBV Support memo). Modify 3D functionality as follows: The particle size distribution curve is a cumulative distribution of mass according to particle size. In the previous package and Potyondy et al. (2025), it was a cumulative distribution of particle counts. Specimens are loaded four times faster than before, this is still approximately quasistatic. Platens are now disks; they used to be infinite planes. Radial stress and radial strain are measured as average from three overlapping measurement spheres along specimen axis. Radial stress used to be measured from a single measurement sphere at specimen center. Radial strain used to be measured from ring of bonded blocks at specimen middle. Confined tests behave as follows. Apply and maintain stress boundary condition on sides. Apply stress to axial boundaries by activating platen wall servoes, then deactivate the servoes and specify platen velocities for subsequent test. Confined tests used to maintain stress boundary conditions on entire specimen boundary. REFERENCE: Potyondy, D. O., Fu, W., Purvance, M., & Mas Ivars, D. (2025). A 3D subspring network breakable Voronoi model for rock. Rock Mechanics and Rock Engineering.
9.4	9.00.180	06/13/25 Update snbvMemo to note that the name of the grain-strength parameter {with FISH name UCSrat} is incorrect in Table 1 of the Potyondy et al. (2025) journal paper. The correct name is {UCS to tensile strength ratio (sigma_c / sigma_T)} with capital T instead of lowercase T.
9.3	9.00.180	06/10/25 Provide link address to snbvPkg on Itasca website. Update snbvPkgMemo.
9.2	9.00.179	04/01/25 Confirm that package works with PFC 9.00.179, and minor updates to snbvPkg memo.
9.1	9.00.177	02/24/25 Release SNBV package to the world.

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