Why Results from the .ctf File May Differ from Those in the .xtf File

Why results from the .CTF file may differ from those in the .XTF file

The .CTF file is an instantaneous "snapshot" of the status of all contact surface segments at the time-step when the dump took place.

The .XTF file output is generated within Ansys LS-DYNA by averaging contact forces on each surface over the time period since the previous time-history dump. Therefore the results are not instantaneous.

There are pros and cons to both approaches: the averaging used for .XTF output means that very fast spikes are not missed, but their magnitude is attenuated by the averaging process; whereas the instantanous data in the .CTF file reports the correct magnitude but, in doing so, may miss a spike altogether. The .XTF approach is better for time-history plotting, and the .CTF approach for graphical output.