Can anyone explain deflection differences in Abaqus?

[kangdongyu]

Hello,

I am making a 2D simply supported beam on Abaqus.

Deflection from Abaqus is 9.81e-6 with cubic formulation.

However, when I use deflection formula (WL^3/48EI), I get 9.798e-6

There is not big difference between those two values, but I would like to know there is any way I can get both same values or I made a wrong model on Abaqus. 

Can anyone explain deflection differences in Abaqus?

 

[ebdoep2]

Which elements are you using? Really need a whole lot more information to help you.

That equation comes with several assumptions. One is that the beam is much longer than it is thick. This is the one people usually violate. The next is it only really applies to small deflection which I am guessing you are running a linear FE model and it seems your deflections are small (assuming the beam is much greater than 9.8e-6).

Assuming you choose the correct beam element and a few other things you can get these numbers to match to several digits.

 

[kangdongyu]

Sorry for lack of information.

I used 2D wire with rectangular profile (8x1.575)
Beam length is 38
Depth is 1.575
Width is 8
Global seed size is 1
Also, I applied -1000(y-direction) on centre of the beam.

I hope that information is enough to correct my errors.
Thanks you.