stack test of a steel drum

[kpb11]

Hello All,

I am performing stack test on steel drum where three drums are stacked over the other and palettes used in between. I have done the analysis by giving or trying in two different boundary conditions. The results what I see is extreme and doesn't seems to be realistic.
1. By fixing only the radial of bottom surface in XYZ Translational, result I get is stress=1441MPa and displacement=174mm (Yield limit of steel is 180MPa)
2. By fixing the whole surface of bottom in XYZ translational, result is 91.5MPa and D=1.1mm which is very much within the yield limit.

I am not sure which is the correct result and parameters used is as follows,

Radius = 278.149mm
Depth (h) = 907.65mm
Density = 1.8e-6 kg/mm3
Gravity = 9810e-6 mm/s2
Weight of single drum (empty) = 12.5kg = 0.12N *2 = 0.24kN
Palette weight = 30kg (30/4 = 7.5kg)
For 2 palettes, 7.5*2 = 15kg = 0.15kN
and equation used to calculate force,

Force = {2*(Bottom surface area * Density * Gravity)+ Weight of two drums + Weight of palettes}
=[{2*(Pi x r^2 x h) * rho * g} + (Weight of D1+D2) + (Weight of palettes)]
F = (3.89 * 2) + 0.24 + 0.15
F = 8.18kN (Force applied on bottom most drum)

Can somebody help me in suggesting about the right way of doing the analysis? I also want someone to validate my calculation and especially the Si units used. I tried with 2nd boundary condition because i see the unrealistic behaviour of bottom surface of a drum showing very high displacement. It will be of great help if someone can suggest me on this !!

 

[desertfox]

Hi

Not sure how you get a density of 1.8 x 10^-6 kg/mm^3 the density of steel would be 7.86 x 10^-6.
What is the drum actually like because from your post I only have the mass and radius which leads me only to conclude its a solid disc but I know that can't be right. For anyone to check your calculation we need to verify the bottom radius of the drum for ourselves so a sketch would be helpful with the dimensions.
Also I do not understand how you are getting the high displacement of 174mm can you please show how your obtaining that.

 

[kpb11]

Hi desertfox,

Please see the attached ppt. Actually the drum is filled with a material having 1.8e-6kg/mm3 density and the filling is 95%. and hence i have considered the depth at 95% filling.
in the equation, i have used filled material density.

 

[desertfox]

Hi

The material is .7mmm thick is the 278mm the inner radius or outer radius?
The worst stress is at the open top of the drum where the mass of the other two drums are acting on it, that of course assumes the bottom of the drum is resting on its full area and assuming the drum is not tapered to much.
My calculation suggests at the top rim of the drum you have less than 1Mpa so it should be okay however we could still do with seeing your calculations and I have still no idea how your calculating those deflections.

 

[kpb11]

Deserfox,

Yes, 0.7mm is the thickness of the steel drum. FE model is built in mid-surface and hence radius is taken at mid surface and it is 278mm.

So, you mean to say, second boundary condition where the whole bottom surface is fixed is the right way to go ahead? the deflections what is seen is from the animation (using hyperview to check the deflections and stress). I notice this high deflection with the first boundary condition and looks unrealistic! and hence I tried with

Do you think, with 0.7mm thick steel drum is capable of taking load of 8.18kN? I am just not able to conclude as I feel cylindrical drum can take more load than a square box. In practical, box tends to buckle/bulge more than a cylindrical section with same load. By keeping in this mind, if i see the results, 90Mpa with whole bottom surface fixed, is too less! worst thing, I don't have any previous test data to compare.

 

[desertfox]

Hi

I missed the 3.89kN in my first calculation however I still don't get above 7 Mpa for the stress when I include it.
All I have done is used the 278 radius with a tolerance of +/- .35mm and worked out the cylindrical area and divide that into the 8.18kN force.
The above is the stress on the open top of the bottom drum ie where the pallet is sitting.
If however the bottom of the lowest drum is sat on a 0.7mm wall thickness then that is where the greatest stress will be because it carries the weight of the material inside the drum.
I cannot tell from the picture you posted what surface area is in contact with the floor, I guessing that they are sat on a 0.7mm rim but I await your confirmation.

 

[Tmoose]

Depending on what is filling the drum I would wonder about the possibility of buckling when a lot of the load happens to be applied accidentally eccentrically locally to one edge of either the top or bottom of the drum, over a region of the wall which also happens to have been dented or creased in handling.
I picture pallets generally spreading the load over the ends of drums, but not necessarily equally.

These guys seem to say it always takes less than 38,000 lbs to crush a 55 gallon steel drum.

http://www.beacontechnology.com/PDF/Drum_Handling_Equ.pdf