Dear All

This model was created using SolidWorks 2011 and I am using SolidWorks Premium. I got 2 different answers for the displacement of the 2mm sheet from the SolidWorks simulation and from the practical test. Max. displacement from the simulation is 0.672mm and the max. displacement from the practical test is 2.8mm. Used  Material  is Aluminium 2024 T3 and the properties of actual material and solidworks library material  are equal. Applied pressure was 3 bar. Simulation which I did was attached herewith. Can anyone please help me to find the reason for this deviation?