Software: FLAC: Pre-Release 6.0

Enhanced Grid Generation

Substantial additions to the grid generation tools in FLAC 6.0 make model construction easier, faster, and tremendously flexible. The "regular" command-execute mode of grid generation is still available — now called "one-step" mode — but, in addition, there is a new "virtual" mode of grid generation. In this mode, commands are not executed until the grid is completely constructed. Working in virtual mode, limitless undo/redo operations are possible, meaning the risk of extensive effort to correct errors when constructing a grid is eliminated. In addition, the virtual grid is stored with the model as an object itself separate from the executed grid. This allows the user to return to the virtual grid for other purposes, either to modify the model or to use it as the basis for a new one.

The following image series show some basic operations in virtual mode to construct two different grids: a tunnel and a slope. (There is a five second delay between the frames in each series.)

As seen in the images, the virtual mode operates in three principal stages: blocks, boundaries, and mesh. Each stage contains tools that assist in model design. In blocks mode, node points allow for manipulation of the base grid shape. A new "merge node" capability allows separate grid objects to be easily joined. Grid objects may be duplicated, rotated, re-sized (both proportionally and stretched), and joined back to their parent objects. In boundaries mode, all boundary specification (marking, setting attaches, interfaces, or beam-interface boundaries) can be peformed visually. Properties for boundaries may also be specified. True curved grid boundaries may be specified as ellipses or polylines. In mesh mode, each subsection of the grid may given an automatic mesh assignment (coarse, medium, fine) or user-specified. Using a pre-defined mesh density will automatically create the "ATTACH" commands necessary to join grid subsections.

In addition, the built-in grid library has been greatly enlarged, with 38 pre-built grids that supply a range including cylinders, footings, radial shapes, seams, slopes, tunnels, and walls. With the new virtual grid mode user-defined grids are easily added to the library as well.