jj77
posted this
21 January 2019

- Last edited 21 January 2019
Explicit time integration can be used also for dynamics (say wave propagation or high freq. vibrations, or impact vibrations), so you do not need to use a modal analysis (you could not couple the two anyhow, since one is in freq, domain the other time marches in time).

(Normally not used for very long events of low freq. vibrations, say of an seismic event).

You just need to look with a probe say on the Y displacement on the part of interest and plot these. From there you can do an FFT and see for any frequencies, if you like that. That could of course be compared to a separate modal analysis of the cutting tool, in order to identify its freq.

In order to capture, the vibrations of the part, you also need to have a dt (time step) in explicit that is at least 10 times smaller than the highest frequency of interest. Normally this should be OK, since explicit uses a very small time steps (dt~L/csound),

In any way running explicit means that you care about the event of cutting and the dynamic stresses generated there. If you just run a modal analysis that is only to identify how the tool might vibrate, it does not tell you though how it will vibrate during the cutting process and how large the stresses will be.

For that you need to run explicit transient dynamics (or implicit if possible), since the cutting process is a transient event