It took over a year to find a pair of engineering programs that let evolutionary biologist Elizabeth Dumont at U Mass, Amherst, convert, mesh, and simulate loads on small bat skulls. Dumont's process starts with a microCT scan of the skulls that produces details with 0.2 mm precision. The second program creates a usable mesh of 250,000 elements on models a little more than 1-in. dia. Dumont is looking for the structural variations in different bat species. “The skull structure is influenced by diet. And because they fly, skulls have to be lightweight. We are looking for the differences influenced by dietary shifts. This involves examining the stresses and loads a skull can carry, hence the FEA,“ she says.

But there is nothing regular about a skull. It's a collection of small and irregular details some of which are not needed. “For instance, a hollow space underneath the cheek bone, and complexity inside the nasal and ear cavities were edited out with GeoMagic Studio.“ The software for manipulating scanned data comes from Raindrop GeoMagic Inc., RPT, N.C., (geomagic.com). “This manipulation software produces ‘watertight’ STL files and outputs IGES files that are read into Strand7 from Beaufort Analysis Inc., Beaufort, N.C., (beaufort-analysis.com). The FEA program was able to import the IGES files and mesh the skull model with plates which were easy to align. A check program in the FEA package pinpointed the few that did not align and allowed corrected the misalignments. Nodes in adjacent plates must align properly to transfer load. A single command then replaced the plates with solid tet elements.

What's more, the visual nature of both programs improved communications between the engineering and biological portions of the research team. “To avoid confusion, we often pointed to details in discussions and each knew what the other meant.“

Because of the small details, other FEA programs in the engineering department were choking on the volume of elements. Most are student editions and limited in that regard.