Hi: Recentlly we tested a composite panel for uniform pressure load and tablulated the deflection at few location where we were intersted.But when I tried to use hand equations to calculate the stiffness/deflection and I got totally diffefrent results for deflection.Actually deflections are more in hand eqations. Now am I wondering which deflection to use to calculate stiffness. If I use from hand results, stiffness (total load from pressure /deflection)is not acceptable because sfiffness is small than required. Can anyone tell what I am missing? Thanks in adwanse.