Update Dynamic_FSI_Python.md

_tutorials/multiphysics/Unsteady_FSI_Python/Dynamic_FSI_Python.md

@@ -217,11 +217,11 @@ Available keywords for the config file:
 
 * __MOVING_MARKER__ (string): name for the interface marker
 
-* __IMPOSED_MODES__ (list): In case of imposed motion this list contains the modes with imposed motion and the type of motion. Example: ```IMPOSED_MODES={0:"SINUSOIDAL",3:"BLENDED_STEP",4:"SINUSOIDAL"}```.
+* __IMPOSED_MODES__ (dictionary): In case of imposed motion this list contains the modes with imposed motion and the type of motion. Example: ```IMPOSED_MODES={0:["SINUSOIDAL"],3:["BLENDED_STEP"],4:["SINUSOIDAL"]}```. If more imposed motions have to be superposed on the same mode, we can write: ```IMPOSED_MODES={0:["SINUSOIDAL","BLENDED_STEP"]}```
 
-* __IMPOSED_PARAMETERS__ (list): Depending on what was selected above, different parameters are required to complete the definition of motion. For example, in case of a sinusoidal motion, it is required to know if there is a bias, the frequency and the amplitude. If we want to specify a sine with no bias, 20 of amplitude and 10 Hz of frequency for mode 7, we would write: ```IMPOSED_PARAMETERS={6:[0,20.0,10.0]}```. For more information about these parameters please look at the module ```pysu2_nastran.py```
+* __IMPOSED_PARAMETERS__ (dictionary): Depending on what was selected above, different parameters are required to complete the definition of motion. For example, in case of a sinusoidal motion, it is required to know if there is a bias, the initial time, the frequency and the amplitude. If we want to specify a sine with no bias, initial time of 5s, 20 of amplitude and 10 Hz of frequency for mode 7, we would write: ```IMPOSED_PARAMETERS={6:[{"BIAS":0.0, "AMPLITUDE":20.0, "FREQUENCY":10.0, "TIME_0":5.0}]}```. Please note that more imposed motions can be superposed on the same mode simply adding more entries for the same mode: ```IMPOSED_PARAMETERS={6:[{...},{...}]}```. For more information about these parameters please look at the module ```pysu2_nastran.py```. Note that the order of the parameter dictionaries must be coincident with the order defined in IMPOSED_MODES dictionary.
 
-* __INITIAL_MODES__ (list): list containing the initial amplitudes of the modes. Example is {0:0.1,1:0.0,3:5.0,...}
+* __INITIAL_MODES__ (dictionary): list containing the initial amplitudes of the modes. Example is {0:0.1,1:0.0,3:5.0,...}
 
 We will call the Nastran model modal.bdf and, after the eigenvalue analysis, we will obtain the files modal.f06 and modal.pch.