Free Decay Test

Hi Yuni,

We have a sample file that shows the different decay curves for different bilge keels.  Please see the b_keels set of files in the following directory.

C:\Program Files\Bentley\Engineering\MOSES CONNECT Edition V12\hdesk\runs\samples\how_to

Georgina Maldonado

Dear Georgina,

regarding the decay test.

i have few questions, understand the peak1 is the initial roll (in this case is 10deg), but why for the peak2 the value is when t is tp2=tp1 + 0.25*period? because that t is not the second peak of roll right?
and also for the period why is taken only from 1st peak to 1st through?

Thanks and regards
Nafuat

Hi Nafuat,

The definition of Tp2 is a decision made by the user in calculating damping ratio. In this example we define Tp2 as Tp1 + 0.25*period. Think of it as a timestep in calculating Tp2. Someone may choose a different step where in this case the 0.25 factor needs to change. The 0.25 step is sufficient in this example.

The second roll peak is being printed in the log file.

You could calculate the period from any other oscillation, in this example we are taking the time from first to second peak. Alternatively, the time taken from third to fourth oscillation could be used instead with the necessary changes in the code.

Thanks Spiro.