ansys IRLF

sir 

please guide me for the use of ansys Command IRLF,1...

this is used for  static analysis of free free model ..but in free free model like flying aircarft .. it is a dynamic system..

and please also suggest about the significance of displacement and stress plot under this analysis..

i am very much confused in analysing these structure..and applying contraints...

i need your expert advice in  this regards

thanks...

-dileep