Shell expansion can be performed on 2d or 3d entities using the "scale" command.  The center of the shell and amount of shape size change (factor) is needed.  AutoCAD R14 can use lisp but scripts and VBA are also available.  

The expansion might be more complex than this however.  Are you trying to automate the drafting/modeling of expansion as a result of the application of loads?  Do you want the lisp routine to calculate the new shape and then draw it?  This could involve an outside routine that determines the new shape and exports its information to AutoCAD for redrawing.  

Mike Van Voorhis
MJVanVoorhis@CS.com

Dear Mike;

Thank you for your valuable reply, this is my first and maybe best answer.

Can you help me more, or do you have Lisp, Script or VBA for this purpose?

Thanx, Ramin
raminb@yahoo.com