How to find Thickness of Plate for 3 tonne load

[Far1979]

Hi Guys,
I have designed a system using a 10 mm mild steel flat bar and 5 mm flat bar assuming that 10 mm mild steel flat bar (40 x 600 mm )would withstand the load of 3 tonne.

Can any one please let me know the procedure to calculate the thickness of a plate to withstand 3 tonne load (based on australian standards)? Also, how much load can 40 mm diameter pin withstand?

 

[Ussuri]

Read the code, check the limits, calculate member forces, compare applied forces to code limits. Confirm design as good, yes or no.

 

[rb1957]

aside from saying "look in any structures textbook' ...
assuming the plate is 10mm thk 40mm wide and 600mm long and assuming that the 3000N load is applied normal to the plate (ie across the 10mm thk) in the middle of the plate, and assuming the the plate is supported at both ends (without rotational support) ... phew, then ...
max moment in the plate = (3000/2)*(600/2) = 0.45MNmm
max stress in plate = 6*0.45E6/(40*10^2) = 675 Nmm^2 = 98ksi
which is good for 125ksi (860 MPa) mild steel.

but then i've no idea about what your "australian standards" require.

you'll have to tell us a little more about the 40mm dia pins

 

[desertfox]

Hi Far1979

How is the plate loaded in bending? what code are you working too?
Can you upload a sketch of your situation otherwise we are guessing what it is you are trying to do.

Regards

desertfox

 

[Ussuri]

rb1957

I think your maximum bending stress is out by a factor of 10. 3 tonnes (3000kg) is approx 30000N, not 3000N.

 

[Far1979]

Hi Guys,

Thank you for your prompt replies. Especially RB1957, thanks for your explanation. But i am still in a situation where i learned a few thinks which i am trying to solve at the moment.

Well,

step 1) b= 90 mm , d= 10 mm ,6= 845 mm flat bar (2 off) is used to slide on the other rail based on the cylinder compression and extension. Basically, this flat bar will experience tension with uniform distributed load situation when the trolleys will guided through the guide as design which you can see in the photo.


I believe that i should use the formula for Rectangular Plate

Bending Moment = M.y/I
and I= b*d^3/12

Am i using the right formula, if yes then what is the value of "M" in bending moment formula (3 tonne ? )

And second Flat bar will experience shear loading when trolley will pass through during compression having dimensions

b=40 mm, l=485 , t =5 mm

what will be the formula for shear loading

And thirdly, the standard rail which 125x65x5 mm will experience shear and bending moment.

can any one please give me an insight on this. I am desparate to solve this . Much appreciated if anyone can address this issue

 

[rb1957]

thx for the pic, i would never have visualised that from your description. this looks like a load lifter ? if so, there are almost certainly some requirements from your loacal standards (safety factors, ...).

where is the 3 tonne load applied ? to one of the orange thingies (and, yes, that's the tehcnical term) ??

are you looking to size the individual orange pieces ? (without a scale it's hard to see what's what)

can you draw a free body diagram, to chase the load through the strcuture ?

 

[Far1979]

Hi rb1957,

Here is the first drawing which is referred as Model-1. The
second drawing is in the next attachement.

thanks,
farooq

 

[Far1979]

Here is the second attachment which shows the detail view of the complete model.

thanks farooq

 

[rb1957]

it looks to me as though you've got a 3 tonne actuator doing something or other.

it looks to me as though this is attached at both ends by a bolt group and eventually this load is applied to the rail (at the top of model1) by a pair of carriages.

if this is right we can probably keep chatting !

but you should be able to follow the loads through the structure.