Hi, Deepak,

                       Just wonder, do you mention different material properties w.r.t different grades being simulated ! If so, just check does your material property variation among grades is significant or not .

Hi Deepak, following Manoj 's answer, you could rank your materials according to strength and check if the vM-streeses Show the same tendency. This helps you to understand if your model is Setup correctly or the Problem arises from somewhat different.

Dear Deepak

First, have you assigned the new material properties, other grads of steel, to the geometry bodies in your model? I am sure there should be some difference in the Von misses stresses even if the difference between the material properties of the steel grads is low.

Second, when you said "There is also no variation of von misses stresses with varying aspect ratio or stiffeners spacing." do you mean there is no Von misses difference even when changing the aspect ratio for the same material properties? 

Regards,