Deflection on structure

[isep2008]

Hello everyone

I need your help for the calculations of this structure (see picture). I have dificulties on interpretate the effords on the beams.
From where should I start?

Thanks

 

[Ron]

Is this a problem for school?

 

[JohnRBaker]

Yea, the 1000kN (kiloNewton) load is sort of an alarm bell ;-)

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

UG/NX Museum:

http://www.plmworld.org/p/cm/ld/fid=209

To an Engineer, the glass is twice as big as it needs to be.

 

[Cockroach]

I would begin at the plate, the vertical load is downward and imparts a load intensity to the two support beams below. You can analyze the deflection of that beam using classical theory.

This would lead you to support reactions, which are treated as a vertical load downwards on the end columns. Note there are cross braces which would need to be determined statically.

The structure is symmetric along length and width. So from the vertical load down on the plate, the counterpart beams would be equally supported.

The deflections would be the sum of elements individually deflecting. So most of it would be at the plate and the beam structure below, then a tiny bit at the columns. The rest of the structure member deflection are probably minor.

It would be a problem for beam software since hand computations would be involved. The deflection of the plate supporting the centre load can be found in Roark's. The rest of the problem would be classical beam theory, extensive computations.

 

[lganga]

Look at the School books about mechanics . "Mechanics of Materials" E. Popov

 

[rb1957]

as cockroach has said above, follow the loadpaths ... the plate takes the load to the short beams, the short beams take it to the frames (here you'll have 4 loads of 250 kN), each frame takes it's load down to the ground.

each link in the chain has to be able to do it's job.

 

[isep2008]

Thank you guys

I have consider your helps and I think it went well. At least based on what Solidworks said
I did the calculations for the top beams and I had to reforce it with some crossed beams.
Now I have another problem. I have to replace the four vertical beams for four round columns (or tube). I calculate the diameter for each and it seems to me that the diameter is very small (about 50mm). I've done it for compression(Euler) and traccion(P=F/A).
When I look at similar presses, it looks to me that the diameter of the the columns are larger, what should I do?

thank you all

 

[Cockroach]

Reconsider your factor of safety. You have the peak load, but what if it was 25% larger? Then redo your computations. This, I expect, would be your "worst case" scenario.

Regards,
Cockroach

 

[isep2008]

Factor of safety=4
P=Yield strengh=335Mpa/4=83.75Mpa
F=1000/4=250kN
P=F/A
From this calculation I've obtained 60mm diameter. I looks small to me but I can't justify a larger one. I wonder if the columns that I've checked on the net are made of tube?

 

[Cockroach]

oh, yeah....you're talking solids?

No they would be seamless tubing, cold drawn, probably ASTM A36 or 1020 equivalent. I would be looking at 1/8 to 1/4 inch wall perhaps.

Regards,
Cockroach

 

[rb1957]

it may not be relevent, but are you checking the column as a column ?

you're using 60mm diamamter ... what wall thickness ?
(surely not solid bar ??)

 

[isep2008]

Hello

I was calculating it as a solid. I've done it as a tube and it seems fine to me.

Thank for your opinion

 

[rb1957]

be sure to check the columns as columns (not necessarily Fcy)