Calculating Stiffness of Aluminum Plate with Pressure Load

[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.

 

[NatSusan]

Hi there,

It looks like you're on the right track with your calculation for stiffness. Just a couple things to consider: make sure you're using consistent units (psi for the load and inches for the deflection) and also double check your calculation for the total load on the plate. It should be 100*40*75/144 = 20833.33 lbs. Also, keep in mind that the stiffness value you calculated is for the entire plate, so it may seem high since it's spread out over a large area.

As for your question about the plate being so stiff, it's likely due to the honeycomb structure. Honeycomb structures are known for their high strength-to-weight ratio and can provide excellent stiffness even with relatively thin face sheets. Additionally, the fact that the plate is supported on all four sides also contributes to its stiffness.

Hope this helps! Keep up the good work in your engineering studies.