Stiffness of beam

[har_rai]

Hi all:

I am fresh to engineering and have basic question.

I have a 100 inch length and 40 inch wide & 6 in depth plate , it has honeycomb structure what I mean 0.125 inch face sheet of aluminum on either side and rest (6-.125*2)is honeycomb made of alumnium.It is supportted on 4 sides.Pressure load on this is 75 psi. I need to calculate the stiffness of this plate for this load.

I know the deflection from test which is 3 inch at the center for this load.

Once I know the deflection then stiffness would be total load on the plate which is (100*40*75=300000 lbs) devided by deflection, which is 300000/3=100000lbs/in.

Do u think I am right in this.Please give some suggestions.

But i am wondering how come it is so stiff (100000 lbs/in)

thks

[FredGarvin]

In the specific case of 1-D you are correct. Since you are dealing with a honeycomb structure, the deflections may not be consistent in each direction. This would mean that you have different stiffness depending on direction considered.

Stiffnesses are usually very high numbers because there are very small deflections for large stresses.