The exact method would depend on which software package you are using, but generally to change the bc's one would remove the old bc's and apply the new bc's. >>> "Ebin Liao"02/06/01 08:24PM >>> Dear MEMS colleagues: I'm doing a simulaiton work on a silicon membrane that is clamped at edges. Becuase of symmetry only a quarter of the membrane must be considered, but I don't know what should I do to change the boundary conditions. Anybody can help me? Thanks in advance! Regards, Liao Ebin __________________________________________________ Do You Yahoo!? Yahoo! Auctions - Buy the things you want at great prices. http://auctions.yahoo.com/