# Fragment

A set of bodies (i.e., balls, clumps, and/or walls) that are connected via (bonded) mechanical contacts are termed a fragment. Fragmentation analysis can be very useful when investigating the fundamentals of damage in bonded-particle models.

The fragment logic is responsible for

• calculating fragments; and
• tracking the fragmentation history.

One must register (via the fragment register command) contact types so that the contact creation/deletion and bond change events can be tracked to maintain the fragment data structure. Tracking is activated at specified intervals with the fragment activate command and is terminated with the fragment deactivate command. When fragments have been calculated, the body attribute fragment (e.g., see ball attribute) is set to the fragment ID. One can list fragment statistics with the fragment list command and analyze the fragment history with FISH in detail. When used along with the model result logic (e.g., see ball results), the fragmentation states can be reproduced as a function of time for post-processing.

In FISH, the fragment catalog number, or the index of the fragmentation tabulation, is used to access specific information about the fragments. One can access the cycle and time at which the tabulation occurred, as well.