Gravity load and unit consistency in Abaqus 1

[Julian2w2w]

For unit consistency I use SI units, for the data below:
Density = 2,680 kg/m3
E = 70.7 GPa v = 0.33
Plastic strain = 0.2 Yield stress = 240 MPa,

In ABAQUS, I input these:
Density = 2,680
E = 70.7 x 10^9 v = 0.33
Plastic strain = 0.2 for yield stress = 240 x 10^6

For the loadings (all acting downwards, in -ve y-direction):
Wind loading = 1.5 kN gravity is g = 9.81 m/s2

In ABAQUS I input,
WL = 1500 and g = -9.81 m/s2

Can you tell me if those are consistent please?

Also, why gravity should be negative?

 

[FEA way]

Yes, that’s correct input when SI units are used.

Abaqus needs to know the direction in which gravity works (models can be spatially oriented in various ways).

Please don’t delete your threads when you get the reply. One of the purposes of the forum is that others can find answers to similar problems solved in the past.

 

[Julian2w2w]

Okay, I thought my silly questions were taking space on the forum. Sorry I will stop removing them.

But why the wind loading which is acting downwards does not have to be negative, but the gravity load has to be negative?

 

[FEA way]

Pressure load always acts in the direction normal to the surface (you can only make it act outwards using negative sign). But I've just noticed that you use Newtons for uniform pressure load which is not correct (with SI units uniform pressure should be in N/m^2). So you should switch the Distribution to Total force.