Help!!! The correct way to apply acceleration

[szleok]

Hi, folks

I have been puzzled by this problem for a long time:
Which way is right?

1. Apply the acceleration on a group of nodes only.
*nset, nset=inputnode
1,2,3,4,5
*boundary, type=acceleration,amplitude=??
inputnode,1,1,9.81

2. Apply the acceleration on the same group of nodes but also included elements which the nodes belongs to.
*nset, nset=inputnode
1,2,3,4,5
*elset,elset=inputnode
10,11,12,13,14
*boundary, type=acceleration,amplitude=??
inputnode,1,1,9.81

(the node 1 to 5 are in element 10 to 14)

The result is quite different!!!

 

[corus]

Nodes don't have mass, normally, but elements do. I suspect that the group of nodes in the first example belongs to more elements than in the 2nd list. Why it worked in the first case, I don't know.

corus

 

[PamCrash]

Hi Folk,
A good source is always the ABAQUS manual:
*BOUNDARY
Specify boundary conditions.

This option is used to prescribe boundary conditions at nodes or to specify the driven nodes in a submodeling analysis. In ABAQUS/Standard it is also used to define primary and secondary bases for modal superposition procedures.

This means you cannot apply acc. at elements by using *Boundary. Therefore results for version 1&2 must be the same.

Seems you're having a gravity problem. Please check out *DLOAD with gravity (GRAV) loading.

Pam