| This model represents a
sample of a welded fabrication, with two plates added to a main member.
One is a tab, sticking out of the side and the other is a doubler plate
laid on the surface. In this instance we could keep this model as a solid,
but there would be two problems: The doubler would be attached over the
whole of its contacting surface and there would be a large number of solid
elements created for even this simple model. |
 |
Go to Model:Idealizations:Connections and
choose End Welds and pick the two surfaces where the tab mates to the
side of the main section. A weld icon appears and the boarders of each
edge turn orange. The connection appears in the model tree.
|
|
|
The answer is to shell
the model by creating shell pairs. In this instace this is
straightforward, since the parts were created using the 'thin' feature,
they are 'Autopaired' correctly. This is the result:
As you can see when you look at the
compressed surfaces there is a gap, equal to the plate width. If we were
to try and run the analysis, it would fail with the 'insufficiently
constrained' error. The answer is to use connections to 'weld' the parts
together.
|
 |
| Now for the
doubler plate. This is attached using a Perimiter Weld which simulates a
lap weld that goes around the edge of the doubler plate. Select Perim Weld
from the Connections menu. Becuase a new surface will be created, the
first thing to do is specify a thickness for the weld. Once this is done
we specify the surface that is going to be used to project the new
perpendicular weld surfaces from. In this case the top of the doubler
surface. Now select which edges are going to be welded. I've selected all
4 edges to simulate a fully welded doubler. Now select the underlying
surface of the main member. A new weld icon appears and details appear in
the Model Tree. |
 |
|
Now when we shell compress again we
get the following view:
The edge weld has had the effect of projecting onto the
main member. But notice that the perimeter weld looks the same, as if it
were not there.
|
 |
| Now we can apply material properties,
loads and constraints in the normal manner. |
 |
| To see the perimeter welds, we have to
review the results of the analysis. Here's a view of the deformed model
with von Mises stress contours. You can clearly see the new sufaces
created by the perimeter weld connection. |
 |
.