Inthispaper,weaugmentexistingtechniquesforsimulatingflexibleobjectstoincludemodelsforcrackinitiationandpropagationinthree-dimensionalvolumes.Byanalyzingthestresstensorscomputedoverafiniteelementmodel,thesimulationdetermineswherecracksshouldinitiateandinwhatdirectionstheyshouldpropagate.